The Danube River Delta (Earth and Environmental Sciences Library) 3031039823, 9783031039829

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Earth and Environmental Sciences Library

Abdelazim M. Negm Daniel Constantin Diaconu Editors

The Danube River Delta

Earth and Environmental Sciences Library Series Editor Abdelazim M. Negm, Faculty of Engineering, Zagazig University, Zagazig, Egypt

Earth and Environmental Sciences Library (EESL) is a multidisciplinary book series focusing on innovative approaches and solid reviews to strengthen the role of the Earth and Environmental Sciences communities, while also providing sound guidance for stakeholders, decision-makers, policymakers, international organizations, and NGOs. Topics of interest include oceanography, the marine environment, atmospheric sciences, hydrology and soil sciences, geophysics and geology, agriculture, environmental pollution, remote sensing, climate change, water resources, and natural resources management. In pursuit of these topics, the Earth Sciences and Environmental Sciences communities are invited to share their knowledge and expertise in the form of edited books, monographs, and conference proceedings.

Abdelazim M. Negm · Daniel Constantin Diaconu Editors

The Danube River Delta

Editors Abdelazim M. Negm Water and Water Structures Engineering Department, Faculty of Engineering Zagazig University Zagazig, Egypt

Daniel Constantin Diaconu Faculty of Geography, Centre for Integrated Analysis and Territorial Management University of Bucharest Bucharest, Romania

ISSN 2730-6674 ISSN 2730-6682 (electronic) Earth and Environmental Sciences Library ISBN 978-3-031-03982-9 ISBN 978-3-031-03983-6 (eBook) https://doi.org/10.1007/978-3-031-03983-6 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Preface

The Danube basin covers about 10% of Europe’s surface area and has a wide variety of natural, socioeconomic and political conditions. Human pressures have increasingly affected the Danube River and its basin (e.g., water and land use, engineering works, water pollution, etc.). They have led to quantitative (water flows, allusions) and qualitative changes in the water, and thus to changes in the morphology of the whale and the delta. These pressures have also affected the functionality of water and flood ecosystems. Danube River Delta (DRD) is the complex result of the Danube and the Black Sea interaction. The collection of natural and man-made phenomena taking place in the Danube basin and at the Black Sea level has generated what we are seeing today in the delta. The Danube Delta is individualized as a physical–geographical unit toward adjacent units (plateau, marine sector). The Danube Delta is included under the category of regional wet plain relief forms on highly fragmented river alluvial deposits. The Danube Delta is characterized by positive relief forms known as grindings and negative relief forms represented by lakes and channels. Today, the delta takes the form of a flat surface with a slope of 0,006 ‰, which is crossed by numerous Danube branches, channels, lakes and marshlands. The particularities of this area have led to its ecosystem, social and economic development being different. Hence, the need to update the studies was carried out for the first time in 1960. The Danube Delta has undergone a period of transformation due to the centralized visions of territorial development of the socialist regime. Local interventions to regenerate ecosystems heavily affected by agricultural or industrial activities are then recorded. The lack of funds to regenerate the deltaic area, experience in implementing projects financed from external sources, constantly changing legislation and with many gaps has led to situations that have eroded natural ecosystems, depopulation of the area and a decline in economic activities. The literature review indicates that there are some sources about the Danube River and its basin but to the best of the editor’s knowledge no recently books exist about the Danube River Delta. Therefore, the idea of this book was born on in Bucharest in October 2019 in a meeting with Dr. Daniel Constantin Diaconu (the second editor). v

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This volume of the series brings together contributions of scientists, experts and researchers from Romania who are involved in research related to the Danube River Delta (DRD) and familiar with its characteristics. The book addresses variety of connected topics to cover the critical issues of the DRD. It includes 13 chapters grouped into 4 parts, including (I) DRD Environmental Change (Chapters The Danube Delta Environment Changes Generated by Human Activities”–“Water Flow Variability in the Danube Delta Under Climatic Changes Conditions”), (II) Water and Waste Management (Chapters “Water Management on the Territory of the Danube Delta Biosphere Reserve” and “Integrated Waste Management in the Danube Delta Biosphere Reserve”), (III) Societal Dimensions: Demographics, Health and Education and (IV) Integrated Sustainable Development. In the following paragraphs, we will provide an overview of each of the 14 chapters focusing on its unique objectives. Part I covers the environmental changes in four chapters. The chapter titled “The Danube Delta Environment Changes Generated by Human Activities” presents the effects of human activity on the environmental state of the DRD and the fluvial response to these anthropogenic interventions. The chapter also presents information on the characteristics and dynamics of sediments transported by the river reflected in the riverbed morphology. It includes 94 references. While the chapter titled “Danube Delta Lakes as Sinks for Natural and Anthropogenic Environmental Changes” provides detailed study of bed-sediments of 36 lakes (larger or smaller) from the lagoon–deltaic edifice of the DD were studied in detail. It assesses how environmental and anthropogenic factors may affect spatial and temporal variations in sediment flux and recent sediment dynamics within the DD watersheds. This was done by assessing the main physical–chemical parameters of sediments (i.e., total organic matter, total carbonates and siliciclastic fraction) in 36 lakes of the deltaic– lagoonal edifice. These lakes are of fundamental scientific interest, considering their capacity to contain unique records of environmental depositional processes which have taken place over time. It contains 141 references. Additionally, the chapter titled “Assessment of Climate Conditions and Changes Detected Over the Historical Period (1961–2013)” presents the spatial distribution and changes detected in the main climatic variables, air temperature and precipitation, in the Danube Delta. It also aims to investigate if there is any specific regional pattern and changes in 25 extreme temperature and precipitation indices in the Danube Delta over a historical period (1961–2013) calculated based on gridded data at a spatial resolution of 0.1 x 0.1 ° (latitude x longitude). To the authors’ best knowledge, this study is the first developed research work at such detailed spatial resolution for extreme temperature and precipitation events in the focus region. The chapters contains 99 references. The first part ends with a chapter that analyzes water flow variability in the Danube Delta under climatic changes conditions. The performed quantitative analysis on value ranges for a period of 34 years, indicates the current trends of water leakage in the context of global climate change. It contains numerous figures and a number of 18 references. On the other hand, Part II covered the water and waste management in two chapters. The first chapter is titled “Water Management on the Territory

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of the Danube Delta Biosphere Reserve” and focuses on only on two of the environmental aspects mentioned (elements related to the quality of water in the area and the pressures on water bodies). Particularly, the authors mention only those related to the environmental factor WATER (mentioned in the Integrated Strategy for Sustainable Development of the Danube Delta (2030) (ISSDDD) including the quality status of water bodies, pressures on water bodies, drinking water quality and wastewater, sewerage system and their treatment. It contains 20 references. The second chapter of Part II is titled “Integrated Waste Management in the Danube Delta Biosphere Reserve” it is a documentary study on the generation and management of waste in the Danube Delta Biosphere Reserve. Waste, the end result of anthropic activities, is a growing problem for environmental protection. Several types of waste are generated in the Danube Delta Biosphere Reserve. These include household waste, floating waste, agricultural and food waste, medical waste, etc. It contains 27 references. Part III covers societal dimensions in terms of demographics, health and education in three chapters. The author of the chapter titled “Specificity of the Demographic Dynamics in the Danube Delta” performs a detailed analysis of population dynamics in one of Romania’s most isolated territorial systems, namely the Danube Delta. From a demographic point of view, this is a vast area that faces specific problems of isolation due mainly to the natural environment and its peripheral location both in Romania and in the EU. Knowing the specificity of demographic dynamics is extremely important in shaping the relationship between the demographic component and the local economy, being an important element that must be considered in designing effective sustainable management plans. It contains 40 references. While the authors of the chapter titled “Medical Infrastructure Evolution and Spatial Dimension of the Population Health State from the Danube Delta” analyze the medical infrastructure evolution in the period 2000–2019, including the influencing factors. Additionally, they want to reveal the spatial disparities in the distribution of medical infrastructure, related to the territorial administrative units which are belonging to the Danube Delta. As study case, the malignant tumors situation is used for creating a comprehensive image upon spatial distribution of this affection, related to the Danube Delta natural and cultural conditions. And the author of the chapter titled “The Danube Delta: Opportunities of Content Exploitation as Language Learning Experiences” explains the “Content and Language Integrated Learning (CLIL)” approach, which uses real information and a wide range of authentic materials to enhance language skills and students’ exposure to new content. The method is used in language teaching and learning process in connection with an approach to learning philosophies which aims to bring education closer to the realities of our world, i.e., environmental education. She uses this combination of approaches to combine the scientific content of Danube Delta-related topics with language practice opportunities. This amazing combination of teaching and learning approaches could facilitate the exploitation of various resources with the double aim of raising awareness and increasing students’ knowledge and, on the other hand, of creating opportunities for language acquisition.

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In Part IV, the authors discuss the integrated sustainable development in five chapters. The chapter titled “The Societal Benefits as Results of Managing the Danube Delta Landscape and Changing the Stakeholders’ Behaviours” provides the results of the analysis of the dynamics and interlinkages between the DRD governance and Danube Delta landscape, highlighting the influence on ecosystem services and the behavioral change of the key stakeholder in applying the nature-based solution to solve the Danube Delta’s ecological and societal challenges. It contains 53 references. Additionally, the chapter titled “Climate Suitability for Sustainable Economic Growth Through Tourism in the Danube Delta” assesses the climate suitability for a possible extension of the season for outdoor tourism by using an enhanced version of the TCI (ETCI) to analyze if occupancy rates in the accommodation structures (and other related economic indicators) correspond to local weather conditions. Also, the authors propose two development scenarios for sustainable economic growth based on tourism in one of the most famous protected areas in Europe. It includes 64 references. In addition to that, the chapter titled “The Structural Dynamics of the Local Economy in the Danube Delta” aims to conduct an analysis of the economy of the most spectacular isolated habitat in Europe, the Danube Delta. Therefore, the chapter includes an analysis of the economic subsystem of the Danube Delta, a geographically isolated territorial system, with an economic evolution resonant with the context of the national supersystem, but with many specificities determined by geographical particularities. It contains 59 references. On the other hand, the chapter titled “The Role of Tourism Activities in the Integrated Economic Development of the Danube Delta” analyzes the main important indicators for the tourism activity in a very visited destination of Romania, a unique one, the Danube Delta. Among the indicators, the arrivals, overnight stays (as tourism traffic) and the number of companies, of employees (as jobs), the value of profit and the turnover have been analyzed. The chapters uses 54 references. Additionally, the chapter titled “Danube Delta Integrated Sustainable Development Strategy.” It focuses on analyzing the strategic documents developed by European, national, regional, county, and local authorities and highlightes the opportunities and constraints for the development of the Danube Delta. The analysis results in a set of very useful conclusions to help the concerning authority and stakeholders to strengthen the weakness in the analysed strategies. The editors want to thank the contributing authors who made this high-quality volume a real source of information and knowledge on the interesting Danube River Delta by presenting the latest research findings related to DRD environmental, economic and social issues. Without the patience and efforts in writing and revising the different versions of the manuscripts to satisfy the high-quality standards of Springer, it would not possible to create this unique book and make it a reality. Great thanks are due to the reviewers of the chapters and the editors of the Earth and Environmental Sciences Series for the constructive comments, advices and the critical reviews. Additionally, acknowledgements should be extended to include all members of Springer team who have worked hard for a long time during the COVID-19 pandemic to produce this volume.

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The volume editors will be pleased to receive constructive comments from their peers, stakeholders and decision-makers to improve future editions. Comments, feedback, suggestions for future improvement or new chapters on the DRD for the next editions are most welcome and should be sent directly to the volume editors via their email that are posted in the chapters. Zagazig, Egypt Bucharest, Romania January 2022

Abdelazim M. Negm Daniel Constantin Diaconu

Contents

Danube River Delta Environmental Change The Danube Delta Environment Changes Generated by Human Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Laura Tiron Du¸tu, Nicolae Panin, Florin Du¸tu, Adrian Popa, Gabriel Iordache, Iulian Pojar, and Irina Catianis Danube Delta Lakes as Sinks for Natural and Anthropogenic Environmental Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Irina Catianis, Adriana Maria Constantinescu, Albert Scrieciu, Iulian Pojar, and Laura Tiron Du¸tu Assessment of Climate Conditions and Changes Detected Over the Historical Period (1961–2013) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Adina-Eliza Croitoru, Csaba Horvath, and Titus-Cristian Man

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Water Flow Variability in the Danube Delta Under Climatic Changes Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Maria Cristina Trifu, Constantin Borcia, Ecaterina Luca, and Roxana Bojariu Water and Waste Management Water Management on the Territory of the Danube Delta Biosphere Reserve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Petru-Dragos, Morar, Dana Rus, and Abdelazim M. Negm Integrated Waste Management in the Danube Delta Biosphere Reserve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Petru-Dragos, Morar

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Societal Dimensions: Demographics, Health and Education Specificity of the Demographic Dynamics in the Danube Delta . . . . . . . . . 175 Cristian Constantin Dr˘aghici, Alexandra Grecu, Cosmin Olteanu, Alexandru Paru, Andreea Karina Gruia, and Vasile Gabriel Dasc˘alu Medical Infrastructure Evolution and Spatial Dimension of the Population Health State from the Danube Delta . . . . . . . . . . . . . . . . 203 Marian Marin, Iulia Nedelcu, Donatella Carboni, Anca Bratu, Secil Omer, and Alexandra Grecu The Danube Delta: Opportunities of Content Exploitation as Language Learning Experiences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Dana Rus Integrated Sustainable Development The Societal Benefits as Results of Managing the Danube Delta Landscape and Changing the Stakeholders’ Behaviours . . . . . . . . . . . . . . . 269 Camelia Ionescu, Corina Gheorghiu, and Tanvi Walawalkar Climate Suitability for Sustainable Economic Growth Through Tourism in the Danube Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291 Adina-Eliza Croitoru, Adina-Viorica Rus, Titus-Cristian Man, Victor Malair˘au, and Alexandru Matei The Structural Dynamics of the Local Economy in the Danube Delta . . . 317 Daniel Peptenatu, Andreea Karina Gruia, Alexandra Grecu, Camelia Teodorescu, Marian Marin, Raluca Dinescu, C˘at˘alin R˘azvan Dobrea, Razvan Mihail Papuc, and Cosmin Olteanu The Role of Tourism Activities in the Integrated Economic Development of the Danube Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363 Radu-Daniel Pintilii, Andreea Karina Gruia, Alexandra Grecu, Oana Cret, u, and Donatella Carboni Danube Delta Integrated Sustainable Development Strategy . . . . . . . . . . . 387 Daniel Constantin Diaconu, Mihnea Cristian Popa, Daniel Peptenatu, and Abdelazim M. Negm

Danube River Delta Environmental Change

The Danube Delta Environment Changes Generated by Human Activities Laura Tiron Du¸tu, Nicolae Panin, Florin Du¸tu, Adrian Popa, Gabriel Iordache, Iulian Pojar, and Irina Catianis

1 Introduction The impacts of human activities on the fluvial systems have been investigated for a long time by numerous scientists [1–8, and many others]. Human interventions in a fluvial system (dams, dikes, dredging, groins, meander bends cut-offs, etc.)

L. Tiron Du¸tu · N. Panin · F. Du¸tu (B) · A. Popa · G. Iordache · I. Pojar · I. Catianis National Research-Development Institute for Marine Geology and Geoecology – GeoEcoMar, 23-25 Dimitrie Onciul Street, RO-024053 Bucharest, Romania e-mail: [email protected] L. Tiron Du¸tu e-mail: [email protected] N. Panin e-mail: [email protected] A. Popa e-mail: [email protected] G. Iordache e-mail: [email protected] I. Pojar e-mail: [email protected] I. Catianis e-mail: [email protected] A. Popa Faculty of Geology and Geophysics, Doctoral School of Geology, University of Bucharest, Traian Vuia Street, no. 6, 020956 Bucharest, Romania G. Iordache Faculty of Geography, Doctoral School “Simion Mehedin¸ti”, University of Bucharest, 1 Nicolae B˘alcescu Blvd, 010041 Bucharest, Romania © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_1

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modify the hydrological and sedimentary characteristics of rivers that control the environment and the geo-morpho-dynamics of the river courses [9–21]. The last two centuries have been marked by the construction of dams on numerous rivers, such as the Mississippi River, Yellow River, Nile River, Danube River, etc. [9, 22, 23]. At the same time, several studies have been carried out on the impact of the abovementioned structures on the riverine environment, on hydrology, sedimentology, and morphology [23–29]. Depending on its location, environment, substrate, and variables of control, each river responds differently to disturbances induced by dams [9] as they change the seasonal variability of liquid and solid discharges [30]. [31, 32] estimated that over 40% of the water flow of the world’s rivers is currently intercepted and 25% of the solid discharge is trapped behind dams. Studies by [33] show that in the modified river courses of Central Europe, 50-year-frequency floods have decreased by 20% and ten-year floods can decrease up to 75%. An example of the extreme impact of the construction of such reservoirs is that of the two Aswan dams on the Nile (the first dam, the old one, built-in 1902, and the second, new, dam, finished in 1970); the Nile suffered a reduction in total sediment load transported downstream from 100 × 106 t·y−1 to almost zero [30, 34]. Meade and Parker [35] studied a similar impact on Colorado (USA), which experienced a decrease in sediment load transported from 125–150 × 106 t·y−1 in 1930, to 1.1 × 106 t·y−1 now-a-day. The Mississippi River (at Baton Rouge) shows a similar decrease in sediment discharge between 1950 and 1975, following the construction of five dams, between 1953–1963, on Missouri [30]. Reservoirs built on the Yellow River (16 barrages, among them the Sanmenxia and Xiaolangdi dams) have induced reductions in sediment flow (up to 60%) [6] with an impact on the development of the delta and the coastline. However, it should be mentioned that there are also rivers that have not changed their sediment regime as a result of anthropogenic interventions. Alford [36] refers to the case of Chao Phraya (Thailand), which shows no significant modification of the sediment flow following the development. Other similar cases are described by [30] on the Ob River (Siberia) and the upper Yangtze (in Yichang, China). Besides the impact of hydropower dams and their reservoir lakes, a large number of engineering works can influence the river’s hydro- and morpho-dynamical processes. The meander bends cut-offs for better navigation and for controlling the seasonal floods, stabilization of channels by embankments, etc. represents pressures on the river evolution pattern [37]. Numerous studies, theoretical, experimental, or in situ have shown that the modification of the sinuosity rates (in case of meandering rivers), the reduction in the variability of widths, or plan mobility could be the first response of a river to the construction of a dam [11, 27, 38–42]. Grams and Schmidt [43] demonstrated that the decrease of the channel width is not linearly correlated with the distance downstream from the dam, but is related to the degree of reduction of flood peaks induced by the dam, to the modification of sediment inputs, and local geomorphological characteristics. In the case of meander belts cut-offs, the most important factor that influences the changes in water and sediment flows is the increase of the river free water slope.

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The downstream area of the cut-off will be fed by a larger quantity of sediment resulting from the erosion of the cut-off canal and of the upstream area. Schumm [44] considers that the dynamic equilibrium of a cut-off canal will set in only after a few “local cycles” of erosion/deposition. The best-known example of a large meander bends cut-offs program is the Mississippi River (USA) that have been performed in the 1930s to facilitate the evacuation of floodwaters and improve navigation. The river has been shortened by about 30% of its length (274 km). As the result of shortening, 15 meander bends were cut-off and isolated from the main channel. The river was shortened an additional 88 km between 1938 and 1855 by chute cut-offs. The period following the rectifications had a substantial impact on the morphology of the river by self-adjusting its course [25, 26, 45]. The Danube River (2875 km) is a major fluvial system with a drainage basin of 817 000 km2 [46–48]. In addition, the river and its delta at the mouth in the Black Sea represent a very complex and large natural river-sea system in Europe [46]. A long history of navigation, industrial development, large-scale agriculture, more than 80 million inhabitants present across the basin, multiple hydro-energetic developments are some of the factors that influence the centuries-old evolution of the river. Its longterm evolution is marked by secular climate changes, transformations of the land use in the entire basin that have changed flow types and flood regimes, and reduced the volume of sediment inputs downstream [29, 47–56]. These impacts have been greatly amplified over the last 50 years by the watercourse regulations along the Danube River and its tributaries, including the construction of the two major hydropower dams Iron Gates I in 1971 and Iron Gates II in 1984 on the Romanian—Serbian border [29, 56, 57]. In the last two centuries, several hydro-technical works have been made within the Danube Delta territory, with significant impact on the delta environmental state, on the water and sediment flows, and on the morpho-dynamics of the distributaries, natural channels, man-made canals, interdistributary lakes and polders, the coastal zone of delta front, etc. [1, 54, 56, 58, 59].

2 Study Area The chapter aims to present the effects of human activity on the environmental state of the Danube Delta, and the fluvial response to these anthropogenic interventions. The Danube Delta (5600 km2 ) displays three main distributaries: the Kilia at North, Sulina in the middle, and St. George at South. Unlike the northern branch, which also represents the Romanian - Ukrainian border and has remained almost natural, except its secondary delta, the other two distributaries have been modified for navigation through meander bends cut-offs (Fig. 1). Since the middle of the nineteenth century, the natural hydrological regime of the Danube distributaries was influenced and modified by human activities. Important

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Fig. 1 The Danube Delta map (artificial canals of the rectified meanders of Sulina and St. George distributaries in red lines) and the location of the study area (Mahmudia-M1, the Upper Dunav˘a¸t-M2, and the Lower Dunav˘a¸t-M3 meanders) within the St. George branch

developments began after the establishment of the Danube Commission in 1856 in Gala¸ti, Romania [2, 54, 57, 60–64]. As a result of the extensive hydro-technical works for economic purposes, the total length of the man-made channels increased from 1743 to 3496 km [65] and the discharge of the Danube River to the delta inter-distributaries depressions increased from 167 m3 /s before 1900 to 309 m3 /s in 1921–1950 period, 358 m3 /s in 1971–1980 period and 620 m3 /s in 1980–1989 period [1, 50]. The effect was the perturbation of water circulation and sediment relocation within the delta [57]. In the deltaic depressions, during the ’60s and ’80s, a management plan was implemented for substituting the natural ecosystems with human-dominated ones (e.g., intensive fish and agricultural farms, poplar plantations). Intensive exploitation of reed and fish resources was put into action and large agricultural farms and tree plantations replaced large surfaces of wetlands from the delta [2]. The rectification of the Sulina distributary (Fig. 1) was carried out during the years 1868–1902 and shortened this branch by about 24%. The shortening and deepening of the river channel produced modifications on the hydrological regime inside the

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delta by increasing the water discharge of the Sulina distributary by about 10% (from 7–9% to about 20% of total Danube discharge) [54]. As a consequence, redistribution of water and sediment discharge among the delta distributaries have been recorded [53, 59, 66]. During the years 1981–1994, cut-offs of six free meanders of the St. George distributary were performed to improve navigation. The total length of the St. George branch was shortened by 32 km and consequently, the free-water surface became steeper and the flow velocity and energy (scouring and sediment load transport capacity) increased significantly. The St. George distributary water discharge increased by some 10% influencing the general water distribution among the delta distributaries [56]. The natural meander courses and the newly built cut-off canals evolved differently: clogging processes are very active within the natural courses of the rectified meander bends, while the cut-off canals are actively eroded becoming deeper and widener [54, 57, 67–70]. At almost the same period, the river and the delta systems have been deeply affected by the hydrological and sedimentary changes (reduction of the sediment discharge by some 40%) after the construction of Iron Gates I and Iron Gates II barrages. These changes are felt all along the downstream barrages river course (almost 700 km) and, especially, in the delta front coastal area [54].

3 Methods Complex research and detailed investigation (using several modern methods and technics, such as ADCP, 3D bathymetry, diffractometry) have been performed in the Danube Delta on the St. George branch, which is considered deeply influenced by anthropic activities. Hydrological, morphological and sedimentological data are here presented. These data have been acquired along three meander loops located in the middle part of the St. George distributary: Mahmudia, Upper Dunav˘a¸t, and Lower Dunav˘a¸t (Perivolovca) meanders, named hereafter M1, M2, and M3, respectively. The measurements were made in two different hydrological regimes, at average to high-level waters in September 2016 and, at the end of a high peak of a flood period of spring waters, at the beginning of June 2017. The St. George branch carried out 1264 m3 ·s−1 and 2169 m3 ·s−1 during the measurements. Hydrodynamics (ADCP). The data analysed in this chapter were acquired with two equipment, ADCP Workhorse Sentinel 600 kHz and ADCP RiverRay 600 kHz (manufactured by Teledyne RDI) mounted on a powerboat [69, 71]. During the two field campaigns, 25 transverse ADCP profiles were completed at relevant crosssections of the three meanders: at the bifurcations (sectors A, I, and L), at the confluences (sectors G, K, and N), and along the cut-off meanders (profiles C, D, E, F, J, and M). The marks 1, 2, and 3 describe the position of each profile in the sector: location on the natural single upstream channel (1), on the former meander (2), and the cut-off canal (3) (Fig. 2).

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Fig. 2 Study area, the three meanders of the St. George Branch (Danube Delta). The investigated cross-sections (ADCP profiles and sediment samples) are marked with red lines and the 3D bathymetrical coverage in gray areas

Morphology 3D mapping. Multibeam sonar bathymetry data were collected during two field campaigns on NIRD GeoEcoMar’s RV ISTROS, equipped with an ELAC Nautik SeaBeam 1050D multibeam bathymetric system (ELAC 1050D, 180-kHz). The depth data were processed using the software packages HDP Post/FLEDERMAUS [64, 72, 73]. Grain size analysis of bed sediments. Bottom samples were collected with a grab sediment sampler, on more than 40 sediment stations, distributed along the three meanders, on each investigated cross-section (Fig. 2). The sediment grain size analyses were done by diffractometry using the grain size laser analyzer „Mastersizer 2000E Ver.5.20 (Malvern Instruments Ltd.-Malvern UK). The equipment determines the percentages of particles in the various dimensional classes present in 0.10 μ–1 mm interval with an accuracy of 1% and a reproducibility of 99%. Particles larger than 1 mm were separated by sieving on fractions, weighed, and reported to the percentages obtained by diffractometry [74]. The texture categories (sand, silt, clays) were separated using the Udden-Wentworth logarithmic scale and for the classification of the sediments, the Shepard diagram was used [75–77]. Determination of the suspended sediment concentrations was made in the laboratory using the filtration method. In all the selected cross-sections, water samples (with a 5 L horizontal Niskin-type bottle) were acquired in three verticals (left balk, right bank, and center). The water samples were filtered with a Millipore filtration

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unit, using 4.7 cm acetate cellulose filter membranes of 0.45 μm porosity, according to STAS 6953-81.

4 Results and Discussions 4.1 Overview of Flow Processes The water flux distribution between the natural course of meanders and cut-off canals is varying from one sector to another, depending on several factors such as the ratio between the former and the new canal length, the diversion angle, and the bed level difference between the natural channel and the cut-off canal. Representative measured velocity profiles from June 2017 are used to illustrate the 2D structure of flow at bifurcations (A1, A2, A3, I1, I3, L2, and L3), confluences (G1, G2, G3, K2, K3, N1, and N3) and on the natural course of meanders (J and M) (Figs. 4, 6, 7, 8 and 10).

4.1.1

First Cut-Off—Mahmudia Meander Belt (M1)

In September 2016, at the bifurcation (A1/A2/A3), the water flux balance is conservative (the liquid flow A2 + A3 (1220 + 25 = 1245 m3 ·s−1 ) is equal to the water discharge through A1 (1264 m3 ·s−1 )). The cut-off channel of M1 receives 2% of the upstream flow [73]. In June 2017, at the same location, the cut-off channel of M1 receives 3.8% of the upstream flow. Upstream the cut-off canal entrance (profile A1), the core of high velocity is located on the right side and at the center of the channel. The channel bed is asymmetrical with the thalweg situated on the right side. The flow is directed toward the right bank, in the direction of the cut-off canal entrance, similar to that along the cut-off canal (profile A3). In June 2017, the cross-section through the entrance in the natural course of the meander (A2) shows a sediment deposition zone located on the left side, with low velocities values (0.4–0.6 m·s−1 ) (Figs. 3 and 4). In September 2016, at lower discharge, access through this section of the natural course of the meander was not possible. The water discharge decreases progressively along the natural course of the meander, as well as the flow velocities (from 0.05 to 0.01 m·s−1 in September 2016 and from 0.44 to 0.05 m·s−1 in June 2017). The water flow velocity increased in the cut-off canal (from 0.48 m·s−1 upstream of the bifurcation, on A1, to 0.58 m·s−1 downstream, on A3) in September 2016, and respectively from 0.76 m·s−1 to 0.90 m·s−1 in June 2017) enhances incision processes within the canal. At the confluence of cut-off canal and the natural course of the meander (profiles G1, G2, and G3) several nucleuses of higher velocities persist in the central areas of profiles G1 and G3, while the velocities of G2 (on the natural course) are very

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Fig. 3 Depth-averaged flow velocities (black arrows) at the bifurcation area of M1 cutoff in June 2017

low and homogeneous (0.01 m·s−1 in September 2016 and 0.05 m·s−1 in June 2017) (Figs. 5 and 6).

4.1.2

Second Cut-Off—Upper Dunav˘a¸t Meander Belt (M2)

The percentage of upstream discharge captured by the meander natural course was over 87% of the water discharge in September 2016, and 77.7% respectively in June 2017. The water flow increase in the natural channel; incision processes are identified at the bifurcation sector (I1–I2) with high-velocity values located in the right bank of the profile I1 (Fig. 7). The velocities are homogeneously distributed on the cross-sections, which demonstrates the active dynamics of the difluence/confluence zones of the system (Fig. 8). At the confluence (profiles K1, K2, and K3) several nucleuses of higher velocity have been observed in the central part of profiles K2 and K3 (Figs. 8 and 9).

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Fig. 4 Distribution of local velocities magnitude within cross-sections measured with the ADCP at the upstream bifurcation (profiles A1, A2, and A3) in June 2017

4.1.3

Third Cut-Off—Lower Dunav˘a¸t (Perivolovca) Meander Belt (M3)

The water fluxes at the bifurcation are distributed unequally between the natural course of the meander (L2 = 25 m3 ·s−1 in September 2016, and 78 m3 ·s−1 in June 2017) and the cut-off canal (L3 = 1225 m3 ·s−1 in September 2016, and 2003 m3 ·s−1 in June 2017), with a very high flux in the cut-off canal (≈96–97% of total). In terms of water velocities, in September 2016, the lowest average values (per cross-section) were situated between 0.16–0.50 m·s−1 on the natural channel and the highest mean velocities values were measured on the cut-off canal (around 0.70 m·s−1 in September 2016 and 1.13 m·s−1 in June 2017). The velocities are homogeneously distributed on the cross-sections (Fig. 10). At the apex zone (profile M), the asymmetric shape of the channel indicates obvious aggradation of the river bed in the central part of the channel.

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Fig. 5 Depth-averaged flow velocities (black arrows) at the confluence area on the M1 cut-off in June 2017

4.2 Bed Morphology and Bedforms Classification The anthropic works influenced the local sedimentary transit of the St. George channel and their bed morphology differently. Figures 11 and 12 show the bathymetrical maps of the cut-off canals of the studied meanders. The canals were initially designed to be 7–8 m deep and 75–100 m wide (1984–1988) [67]. Their depth measured thirty years after (in September 2016 and June 2017) is much greater, with a maximum of 22 m and 27 m (relative water depths) for M1 and M3. For meanders M1 and M3, the cut-off canals continue the direction of the main water flux in the natural course, and this determines the taking over of the main water discharge of the distributary by the cut-off canals, while the cut-off canal at the meander M2 which is oriented approximately at 75–80° to the direction of the main flux in the natural course, only a relatively small part of the flow of water and sediments from the natural course enter the cut-off canal. Consequently, the cutoff canals at the meanders M1 and M3, where the flow velocity is very high, are strongly eroded and their depth increased significantly while in the cut-off canal at the meander M2 no strong scouring processes are registered. Bedforms are dynamic sediment accumulations occurring on a channel bottom, being scaled to the flow velocity and channel depth [78] and also depending on

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Fig. 6 Distribution of local velocities magnitude within cross-sections measured with the ADCP at the downstream confluence (profiles G1, G2, and G3) in June 2017

the texture and abundance of sediments. Various bed-form classification nomenclature for bottom sand beds are found in the literature [78–82]. Here, van Rijn’s classification is applied (ripples, mega-ripples, and dunes). The ripples, mega-ripples, small and large dunes are the most common bedforms identified along the canals. The most important factors which depend on their formation are the flow velocity, the depth of the channel, and the texture of sediments. Ripples are primary bedforms with heights up to a few centimeters (length, L < 0.6 m, H < 0.7 m). Mega-ripples are bedforms with a length similar to water depth [80]. The water depth of the St. George branch ranges from 2 to 27 m. Consequently, mega-ripples are defined here by L < 25 m and H < 1 m. Mega-ripples have been identified all along the three cut-off canals, being the most common bedform in the study area. Mega-ripples have been measured as independent forms, or as superimposed bedforms on dunes. The measured mega-ripples dimension was between 1 < L > 25 m and 0.5 < H > 1 m [72]. Successions of small dunes with a height between 1 < H > 1.5–2 m and lengths between 20–30 < L > 400 m are situated especially at the bifurcation (A1-A2-A3, K1-L2-L3) and confluence areas (G1-G2-G3, K1-K2-K3, N1-N2-N3). Mega-ripples were identified on the surface of all small dunes. Large dunes are quite rare, typically

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Fig. 7 Distribution of local velocities magnitude within cross-sections measured with the ADCP at the upstream bifurcation (profiles I1 and I3) and at the apex of the former meander M2 (profile J) in June 2017

greater than 400 m in length and higher than 2 m. A large dune was measured at the confluence of the M1 meander belt, measuring more than 7 m in height and more than 500 m in length (Fig. 13).

4.3 Suspended Sediment Concentrations and Sediment Fluxes The suspended sediment load of a river varies in concentration over time and depends primarily on the precipitation regime in the river basin, the lithology of geological formations and soils within the basin but also, in the same time, on the anthropogenic factor. Most of the sediment load transported by rivers has as source the erosion of soils and geological formations. The anthropic activity (especially building, agriculture, industry) can also introduce significant amounts of sedimentary, but also dissolved fractions. In most cases, the distinction between the fraction due to the

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Fig. 8 Distribution of local velocities magnitude within cross-sections measured with the ADCP at the confluence of M2 and bifurcation of M3 (profiles K2, K3, L2, and L3) in June 2017

natural processes and an anthropogenic fraction is very difficult or even impossible to achieve. Suspended sediment load represents over 80–85% of the total sediment load transported by rivers to the Sea [83]. Attention will be focused on the study of suspended sediments load concentration and suspended sediment discharge. The bedload transport is not included in the calculations of this chapter but is generally estimated as about 10% of the total sedimentary load for most of the rivers [84]. We estimated the discharge of suspended sediments by a common formula described in the literature [85, 86], which is based on correlating the concentration in suspensions with water velocity and section area (the water discharge):

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Fig. 9 Depth-averaged flow velocities (black arrows) at the bifurcation and confluence area of the M2 and M3 cutoffs in June 2017

Fig. 10 Distribution of local velocities magnitude within cross-sections measured with the ADCP at the downstream confluence (profiles N1 and N3) and at the apex (profile M) of the former meander M3 in June 2017

Fig. 11 Morphology of the artificial canals of the M1, M2, and M3 meanders in September 2016

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Fig. 12 Morphology of the artificial canals of the M1, M2, and M3 meanders in June 2017

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Fig. 13 Large dune situated at the confluence of M1 cut-off

Qs = SSC · v · A where Qs is the suspended sediment discharge (kg·s−1 ), SSC is the mean concentration of suspended sediment for the considered section (mg·l−1 ), A is the area of the section (m2 ), and v is the average water velocity per cross-section (m·s−1 ). The concentrations of suspended sediments (SSC) measured on the investigated sections range between 10.0 and 38.2 mg l−1 , in September 2016, and between 5.0 and 24.1 mg l−1 , in June 2017 (Fig. 14 and 15). These values are very low compared to values of the same type of other large rivers: for the Mekong (Thailand) average values of 962 mg l−1 , for Mississippi (USA) 849 mg l−1 , and even 8240 mg l−1 for Rio Grande (USA) [87].

Fig. 14 SSC (mg/l) mean values within cross-sections of the meanders M1, M2, and M3 in September 2016 (continuous line) and June 2017 (dashed line)

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Fig. 15 A box model for SS fluxes by sections of M1, M2, and M3 meanders in September 2016 (A) and June 2017 (B)

At the entrance to the studied meanders area of the St. George distributary the suspended sediment discharge was approximately 18.5 kg·s−1 in September 2016 and, 20.1 kg·s−1 , in June 2017 (A1). Subsequently, at the exit of the three meanders system the suspended sedimentary discharge was approximately 16.2 kg·s−1 , in September 2016, and 52.8 kg·s−1 in June 2017 (N1). The difference is not significant in September 2016 at low discharge, but in June 2017, the sediment flux increases by 32.7 kg·s−1 (N1) at high water discharge. Along the three meanders accumulation of sediments and erosions of the riverbed occur locally as follows: 1.

2.

3.

On M1, in September 2016, from the sedimentary discharge of 18.5 kg·s−1 at the upstream bifurcation (cross-section A1), a very small part, of 0.5 kg·s−1 , enter through the former meander (in cross-sections C and D). On the cut-off channel (between A3 and G3) the sedimentary flow in suspension is increased (from 34.1 kg·s−1 and 45.9 kg·s−1 on profiles A3 and G3). On the meander natural course, the suspended sediment discharge becomes lower (0.9 kg·s−1 on E, 0.3 kg·s−1 on G2) until the confluence. At the exit of the meander, the discharge of 43.1 kg·s−1 on cross-section G1 is settled down immediately downstream forming a large dune. In June 2017, the suspended sediments discharge was along the cut-off canal 20.1 kg·s−1 on A1 and 47.2 kg·s−1 on G3. In the meander natural course, the suspended sediment load progressively decreases from 2.4 kg·s−1 on A2 to 0.4 kg·s−1 on G2, indicating a strong aggradation process within the channel. On M2, most of the suspended sedimentary discharge is transported by the former meander (approx. 59% in September 2016 and 65% in June 2017). Downstream (profile K1) the sum of the sedimentary fluxes K3 + K2 is higher than the load on the cross-section I1 for both sets of measurements. On M3 the distribution of the sedimentary fluxes is similar to M1, the suspended sediments discharge passing through the cut-off canal is between 98–99% of the total discharge of the distributary in both measurement sets. In June 2017, at a high water level, the output sedimentary discharge N1 (52.8 kg·s−1 ) is significantly greater than the input discharge K1 (39.2 kg·s−1 ). This difference shows a sedimentary supply of 13 kg·s−1 from the banks or bed erosion in the confluence area.

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The role of cut-off canals in the distribution of sedimentary fluxes is a very important one. To an even greater extent, the angle between the natural course and the cut-off canal plays a significant role: at sharper angles (below 40–45°) the water and sediments discharge on the natural course is taken over almost entirely by the cut-off canal, while at angles greater than 45° only a small part of the total discharge on the distributary will be captured by the cut-off canal. This situation is found in the studied meanders: at M1 and M3, where the angles between the natural course and the cut-off canals (the diversion angles) are 22° and 23–25°, respectively, the cut-off canals take over 95% of the total discharge while M2, where the bifurcation angles are over 55° the main flow and water and sediment continues to flow on the natural course of the meander and only 12–23% is directed to the cut-off canal.

4.4 Grain Size of Bed Sediments The grain size of bed sediments sampled in September 2016 has been analysed by [74]. The authors found that the bottom sediments of the main natural channel are composed mostly of sand (medium sand, 59–73% on profiles A1, G1, H, I1, and K1, and coarse sand, 78% on N1) with values of the median parameter ranging between 0.196 and 0.680 mm. Therefore, the sorting is relatively good (0.6 < σ i > 0.75) (Fig. 16). In the M1 and M3 meanders, the bottom sediments of the artificial canals (profiles A3, G3, and I3) are formed of medium and fine sand with median values ranging between 0.298 and 0.321 mm, indicating a relatively good sorting and positive asymmetry. On the profiles K3, L3, and N3, the clayey silt sediments with high clay percentages are present. The in situ analyse describes those sediments such as compact material, possible from the bed substrate [74]. On the former meanders of M1 and M3 (on the profiles A2, B, C, D, E, F, G2, L2, M, N, and N2) the sediments are fine and very fine (clayey silt) with weak and very weak sorting. Along M2, the sediments are formed by coarse, medium, and fine sand (median between 0.286 and 0.302 mm). The relationship between the standard deviation (σ i) and the median grain size is shown in Fig. 16; most of the fine sediments from M1 and M3 former meanders are poorly sorted (0.15 < σ i > 2.35) [74]. In June 2017, the sediments of the main natural channel are formed of sand (medium sand, 54–67% on profiles A1, G1, H, K1, and N1, and fine sand, 61% on I1); the median is situated between 0.194 and 0.350 mm with relatively good sorting (0.6 < σ i > 0.8) (Fig. 16). The sediments of the artificial canals (profiles A3, G3, and I3) are composed of medium sand (the median between 0.204 and 0.268 mm), with good sorting and positive asymmetry. On the profiles K3 and N3, the sediments are formed from clayey silt with high clay content. Along the former meanders, samples from profiles situated closed to the bifurcations (e.g., A2, B, I2, and L2) are formed mainly of fine sand (between 53 and 63%). The sediments of the M1 are very fine (clayey silt) with weak and very weak sorting (1.81 < σ i > 2.08). The comparative analysis of the percentage values of the particle size composition between the two sets of samples shows small distinct changes in the sediment’s

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Fig. 16 Grain size distribution diagram: σi = f(M) in September 2016 and June 2017

characteristics. In most cases, the differences between the percentage values for samples collected from approximately the same points in the two campaigns are smaller than the working error of the particle size analysis (the working error of granulometric analyses is a maximum of 5%). In addition to the working error of the laboratory, which is below 2%, errors may occur in positioning the sample’s locations in both field campaigns. Differences in the percentages of less than 3% clay particle from sands found in several pairs of samples (samples collected in 2016 and 2017) cannot be taken into account given the abovementioned errors. There are several cases when the granulometry of the sediments collected in June 2017 differs from that of September 2016. These differences are likely the result of errors due to location positioning (sediment granulometry differs depending on the position in the channel) or different hydrodynamic conditions (difference of the water level).

4.5 Long Term Evolution The first hydrological and bathymetrical impact studies for the Mahmudia (M1) and Upper Dunav˘a¸t and Lower Dunav˘a¸t (Perivolovca) (M3) meanders have been performed by [67], who carried out a sequence of bathymetric measurements during

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Fig. 17 River-bed evolution (1990–2017) in the Mahmudia modified system (after Popa, 1997)

six years immediately after the building of the cut-off canals. The depth measurements at the bifurcation of the Mahmudia meander (M1) (Fig. 17) show that the channel morphology changed continuously during the studied period (1990–1996). Intense aggradation of the meander natural course (aggradation rates up to 11 m, i.e., 1.8 m·y−1 ) and strong erosion processes of the cut-off canal (deepening rates up to 13 m, i.e., 2.1 m·y−1 ) have been identified [67]. Later [69] have analysed the behavior of the meander M1 and its cut-off canal in 2006, during the 100-year recurrent flood. The significant increase of water velocity and SSC in the cut-off canal was observed determining very active erosion processes, while the water and sediment fluxes through the meander natural course were greatly reduced, with a very fast clogging of the channel (decrease of hydraulic energy, depth reduction and formation of islands, immediately fixed by the vegetation, especially by forests on banks). Extending the calculation of the aggradation/degradation rates to our measurements from 2017, we found that, between 1990 and 2017, the natural channel upstream the bifurcation (A1) was eroded with a rate of 1.17 m·y−1 . For the same period, significant narrowing of the channel and important infilling processes were observed on the meander natural course (A2), with rates of 0.55 m·y−1 . The cut-off canal evolved completely in a different way. During the first 6 years after its excavation, a very strong erosion process was recorded in the cut-off canal. The canal deepened from 7.0–7.5 m (depth provided by the execution project) in 1990, to about 20 m in 1996, its width remaining almost unchanged (about 75 m). In the next 20 years, however, there was no significant deepening of the canal (in 2017 the maximum depth was 21–22 m, relatives depths), instead, the erosion worked laterally causing a significant widening of the canal (during 1990–1996 period—the canal width was about 75 m, in 2017—almost 150 m). The limitation of the canal deepening is probably due to a more compact, more resistant to erosion, substrate. Using the imagery analyses [71] explained that before the St. George menders cut-off programme, between 1970 and 1984, the evolution of meanders was marked

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by generally very slow changes, with sometimes local enlargements of the channel, but after the cut-offs, that started in 1984, the narrowing of the channels by banks accretion and channel aggradations within the rectified meanders became dominant processes. Based on the ADCP measurements, the same authors [71] confirmed the importance of the cut-off canals on the geomorphologic and sedimentary evolution of the three meanders. After the artificial works, the three studied meanders showed different responses: on M1, the water flow acceleration in the cut-off canal produced incision processes; consequently through the meander natural course the water and sediment fluxes were reduced. Meanders M2 and M3 have different behaviour; their evolution is depending on the angle of bifurcation between the natural course and the cut-off canal and the free water surface slope increase. After a decade, (our measurements from September 2016 and June 2017) the three meanders register important changes in hydro-morphological and sedimentological behavior. The natural course of M1 undergoes very visible infilling processes related to the decrease in hydraulic energy—the water and solid fluxes have been significantly reduced. During this time the cut-off canal of M1 was continuously strongly eroded, the depth increased from 7–8 m at the beginning (in 1988 when the cut-off was completely operational) up to 27 m, and the width enlarged from almost 75 m to over 110 m in 2017. On M2, the natural course remained the main water and sediment pass-way, mainly due to the high value of the bifurcation angle between the natural course and the cutoff canal (over 55°); this angle makes the flow of water and sediment continue to be directed on the natural course and only about 12–23% to be taken by the cut-off canal. The most important changes have been recorded in the repartition of the water and sediment fluxes along M3, with significant consequences on hydro-morphology and sedimentology of the natural course: in 2006 the water fluxes were almost equally distributed between the meander natural course and the cut-off canal, while, in 2017, the natural course (L2) received only 3–4% of the total flow, with significantly reduced velocities (an average of 0.34 m·s−1 in the cross-section L2, close to the bifurcation, with progressive decrease up to 0.16 m·s−1 in N2). This development is consistent with most of the bibliographic data. [88, 89] describes two temporal phases in the hydro-morphological response of meanders channels versus cut-offs: first, an immediate response that appears just immediately after the rectification, then a subsequent response that sets in gradual and permanent changes over a longer period. Using GIS analyses [57] has identified these two phases in the evolution of St. George’s natural course, especially within the study sector: the immediate response is noticeable from the end of the 1980s. The second phase, after 1990, corresponds to a continuous change of the natural course and the sedimentation on the banks. Kiss et al. [5] and Amissah et al. [90] confirm the rapid response of the Tisza to the cut-offs by bed aggradation, accretion of the banks, progradation of the meanders point bars. On the Wales [91] show that the meander rectification facilitates the progress of aggradation, the reduction of the mobility of the meanders, and the

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widening of the bifurcations and confluences of natural channels and the cut-off canals. Contrary [92] describes an increase in the sinuosity of the Bollin (Cheshire) River after rectification works. Similarly [93] reports for the Sacramento River, where the increase in sinuosity is accompanied by a reduction in the width of the channel. For the Mississippi River [25] show that the rectification of meanders determined the reduction of water levels (by 0.6 to 4.7 m) and an increase of the water-free slope. Nevertheless, there are also opinions [94], that the meanders cut-off introduces only temporary disturbances to the river system. According to the studies performed, the St. George distributary of the Danube Delta is very sensitive to the meanders cut-off programme, with a fast response in increasing its total water and sediment discharges and in the changes of hydromorphological and sedimentological processes within the rectified meanders.

5 Conclusions In all river systems, meander cut-off programmes have an extremely important environmental impact generating changes especially in the hydrological and sedimentological status of the rivers. Within deltas/estuaries, the impact also extends to changes in water and sediment circulation towards or from the inter-distributary depressions. The hydrological changes are mainly due to the shortening of the river’s natural courses length, which means increase in the water-free surface slope and therefore increases in the water flow velocity and of its capacity of sediment scouring and transport. The increase of the flow velocity and its energetic capacity are recorded within the cut-off canals, while the natural courses of the rectified meanders are almost abandoned and important clogging phenomena are noticed. The impact of the cut-off canals depends on the increase of the water free surface slope generated by the respective canal (the course shortening resulting from the meander cut-off), as well as on the bifurcation angle (the angle between the natural course and the cut-off canal, at its beginning). When this angle is less than 30–40°, most of the river water and sediments flow is taken over by the cut-off canal, while the angle is greater than 45–50°, only a small part of the discharge is directed to the cut-off canal. In time, however, even in these conditions in which the inertial energy of the current in the river is directed towards the natural river course, the modification of the water free surface slope will determine the gradual increase of the water and sediment flows through the cut-off canal. The conclusions set out above are illustrated by the situation in the Danube Delta, where the St. George distributary’s free meanders were rectified between 1981–1994, which led to important changes in the environmental conditions delta. The meander’s rectification led to the shortening of the natural course by some 32 km and implicitly to the increase of the free water slope and the water and sediment flow velocity. The results of the present study refer to the situation within the first three meanders of the six free ones of the distributary. The most dramatic situation is on M1 and M3, where the cut-off canals take over 85–90% of the water and sediment flows of the

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arm, while the natural courses of the rectified meanders suffer an intense clogging, with the almost complete stopping of the water circulation on them. The meander M2 behaves differently because the bifurcation angle of the cut-off canal is higher than 55° and it takes only 13–23% of the total discharge which is mostly directed towards the natural course of the meander. The chapter also presents information on the characteristics and dynamics of sediments transported by the river reflected in the morphology of the riverbed.

6 Recommendations In most of the world’s river systems, important hydro-technical works have been carried out, often without knowing in detail what environmental impact they will have. These effects can be amplified to the point of ecological disasters by overlapping modifications caused by global climate change. Advanced knowledge and understanding of the causes of environmental changes in river systems, especially in deltas/estuaries, is the only possibility to achieve their scientifically correct sustainable management. It is, therefore, necessary to establish complex long-term multidisciplinary research programmes for understanding all-natural processes that control environmental systems in the new conditions of continuous climate change and the increased impact of human interventions. Only the multidisciplinary approach of these studies (hydrology, sedimentology, geomorphology, biology, geophysics, meteorology, oceanology, etc.), the use of the most modern techniques and study methodologies, as well as the follow-up of these processes for long periods will ensure their understanding for taking adequate and effective and sustainable environmental protection measures. Acknowledgements The research was fouded by the Ministry of Research, Innovation and Digitization Core Program, Projects PN16450503 (Contract no. 37N/2016) and PN19200401 (Contract no. 13N/08.02.2019) and Project AMBIACVA (Contract 23PFE/30.12.2021).

References 1. Staras M (2000) Restoration programme in the Danube Delta: achievements, benefits and constraints. In: Nijland HJ, CALS, MJR (eds), Proceeding of the IInd ECRR International Conference on River Restoration in Europe 2000. Institute for Inland Water Management and Waste Water Treatment/RIZA Lelystad, Wageningen (Netherlands) pp 95–101 (pub) 2. V˘adineanu A (2001) Lower Danube Wetlands System (LDWS). Obs Medioambient 4:373–402 3. V˘adineanu A, Adamescu M, V˘adineanu R, Cristofor S, Negrei C (2003) Past and future management of Lower Danube wetlands system: a bioeconomic appraisal. J Interdiscip Econ 14(4):415–447 4. Bondar C, Teodor SM (2008) The evaluation of the balance and the management of sediments in the shipping portion of the Danube course. Text prepared in course of the project. Assessment of the balance and management of sediments of the Danube waterway (Schwarz et al., 2008)

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Danube Delta Lakes as Sinks for Natural and Anthropogenic Environmental Changes Irina Catianis, Adriana Maria Constantinescu, Albert Scrieciu, Iulian Pojar, and Laura Tiron Du¸tu

Abbreviations BS: CAR: Ch: Cnl: DD: DR: DM: L: LOD: LOI: SIL: TOM: WC:

Black Sea Total Carbonates Channel Canal Danube Delta Danube River Dry Matter Lake Loss On Drying Loss On Ignition Siliciclastic Fraction Total Organic Matter Water Content

I. Catianis (B) · A. M. Constantinescu · A. Scrieciu · I. Pojar · L. T. Du¸tu National Institute of Marine Geology and Geo-Ecology (GeoEcoMar), 23-25 Dimitrie Onciul St, RO-024053 Bucharest, Romania e-mail: [email protected] A. M. Constantinescu e-mail: [email protected] A. Scrieciu e-mail: [email protected] I. Pojar e-mail: [email protected] L. T. Du¸tu e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_2

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1 Introduction Fluvial systems composed of a hydrological network of rivers, streams, wetlands and floodplains collect and transport sediment from a drainage basin to a depositional basin (lacustrine or marine). These systems are controlled by natural factors (climate, geomorphology, base-level fluctuations) and anthropogenic factors (land use, agriculture, mining, deforestation, construction of dams and river regulation works) [1, 2]. Both factors have a noticeable influence on river discharges and sediment yield that, in turn, drive fluvial dynamics (water and sediment), including hydrologic and geomorphic changes to watersheds. Their impact can be assessed in geo-bio-archives - sediments from rivers, lakes, transitional and coastal environments, which record changing environmental conditions and anthropogenic pressures. Especially, freshwater lakes, lagoons or coastal lakes are good indicators of the magnitude and direction of significant environmental changes that have occurred in the catchment, as they can contain well-preserved and continuous sediment sequences [3]. In addition, they represent an invaluable source of information on their interconnections with several processes, such as, transport and storage of pollutants, eutrophication and silting [4]. The major European macro-geo-system, the Danube-Danube Delta-Black Sea system, has been selected as an example, with the focus on the Danube Delta (DD) area. Since ancient times, deltas have been important hot spots of socio-economic development due to their fertile wetlands and advantageous locations for commerce and navigation. Many human civilizations have evolved near the deltas, as river deltas supported large human populations, in these environments, worldwide [5, 6]. They are also ecologically significant, sustaining biodiversity and providing essential ecosystem services, as purification and supply of fresh water, mitigating floods and droughts, nutrient cycling, food production, fishing and recreation [7–9]. Despite these positive aspects, deltas are also sensitive and vulnerable to environmental changes due to over-enrichment of nutrients, increasing metals and other organic pollutants [10, 11]. Several international academic and research organizations address the vulnerability of deltas, in the context of environmental change, climate change and anthropogenic impact. Growing concern about environmental change has been reported by many researchers in terms of environmental and socio-economic factors, related to changes in sediment flux [12–16]. During recent years, the need to better understand spatial and temporal variability of sediment input along the Danube River (DR) and its delta has grown greatly as the deficit of sediment delivery (caused mainly by extensive DR damming in the early 1970s) continues to present. The known main effect is coastal erosion [17] but there are other potential effects which are less studied—water quality deterioration, shoreline loss, nutrient level deficiency, loss of fishing potential and seawater intrusion. The DD is unique in the world, with a great variety of ecosystems: cross-barred ridges, among which the most important is the initial spit of Jibrieni-Letea-Caraorman [18, 19], a labyrinthine hydrographic network, virgin wetlands and triangular-shaped opencoast deltaic lobes, depending on where the old distributaries of the Danube had their

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outlets [20, 21], which finish into terminal lagoons - Musura, Sahalin and RazimSinoie. This dynamic and relatively pristine ecosystem that are exceptionally rich in species biodiversity [22] demands a special attention due to their vulnerability to environmental change [23–25]. The largest deltaic wetlands are administered as a Biosphere Reserve and are under legal protection of three international conventions as: UNESCO World Heritage Sites, Biosphere Nature Reserve and Wetland of International Importance [26]. This study aims to assess how environmental and anthropogenic factors may affect spatial and temporal variations in sediment flux and recent sediment dynamics within the DD watersheds. This was done by assessing the main physical–chemical parameters of sediments (organic matter, carbonates and siliciclasts) in 36 lakes of the deltaic-lagoonal edifice. These lakes are of fundamental scientific interest, considering their capacity to contain unique records of environmental depositional processes which have taken place over time. Developing a better understanding of the relative abundance of sediments input into the lakes from catchment areas (i.e., allochthonous materials), will help to better decipher the natural and anthropogenic factors impacting recent sediment dynamics in active and inactive DD watersheds. Therefore, the investigated lakes of the delta are of particular importance for understanding environmental changes and future impacts.

2 Study Area 2.1 Danube Delta. Natural Setting The modern DD (Fig. 1) is a component of the European’s major geo-system Danube River - Danube Delta - Black Sea [27].

Fig. 1 Location of the Danube Delta in Europe (a), and Danube Delta - general view (b) (Base maps: https://google.com)

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The DR flows into the northwestern Black Sea (BS) and shapes one of the largest deltas in Europe (5800 km2 ), the second after the Volga River Delta. The DD wetlands support a large number of flora and fauna communities, birds, fish, aquatic and terrestrial species, most of them considered endangered [22]. The main part of the DD is located in Romania and covers an onshore area of about 3510 km2 , respectively 1030 km2 in offshore (to the isobath of - 20 m), while the remaining areas are attributed to the Ukrainian territory [22]. The DD (5800 km2 ) is composed of the Danube alluvial plain (Isaccea-Tulcea sector, 102 km2 ), also known as the Somova-Parches, lacustrine complex, the DD itself (3510 km2 ), the Razim-Sinoie Lagoon Complex (1145 km2 ), the marine coastal waters (1030 km2 ) and the DR between Cotul Pisicii and Isaccea (13 km2 ) [28]. Each wetland ecosystem has specific characteristics unique to a particular area, such as hydrology, geomorphology, distinct species and communities of plants and animals etc. The DD has had a unique history of development and evolution. The interaction of the DR’s flow and the specific environmental conditions along the BS created a very dynamic environment, sustaining freshwater, brackish and saltwater habitats. Historically, the DD coastline dynamics and evolution consisted of well-defined horizontal and vertical depositional sequences growth as fluvial meander-belt bodies, fluvial ridges, lacustrine spits, fossil beach ridges, and relics of the pre-deltaic relief [21]. Even today, this phenomenon continues, so that areas on the delta territory are slightly increased on a yearly basis. A significant example is represented by the newest Romanian land i.e., Sahalin Island (21,410 ha) located at the mouth of the Sf. Gheorghe’s distributary that is composed of alluvial deposits and sand dunes. The hydrological, geological and geomorphological agents i.e., river level fluctuations, sea level changes, fluvial sediment supply and coastal processes crated unique complex landforms found in different zones of the transitional deltaic area [29]. Consequently, the DD is separated into three important depositional facies [30]: i. ii.

iii.

the delta plain, with a total surface area of about 5800 km2 , of which the marine delta plain area includes 1800 km2 ; the delta-front, with an area of about 1300 km2 , which is divided into the deltafront platform (800 km2 ), and the delta-front slope (500 km2 ) and extends farther seaward to water depths as great as 30–40 m; the prodelta, with an area of about 6000 km2 , stretching offshore, at the base of the delta-front slope, down to a depth of 50–60 m; to this depositional unit, the Danube submarine fan systems are included; the Danube fan system is a relict sedimentary deposit in the northwestern part of the BS, extending throughout Romania, Bulgaria and Ukraine, from a depth of around 600 m down to the abyssal plain (about 2200 m deep) [29].

The delta plain is divided into two main regions: the upper or fluvial delta plain, to the west – a labyrinth of river channels, shallow lakes surrounded by dense vegetation, bays, floodplains, reed beds [31] and sandy levees, a transition zone with several larger lakes and reduced sedimentation, as well as the lower, marine delta plain (active delta), to the east, characterized by dune, sand bars, marine levees [28, 32] and

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marginal lagoons. These two main regions are separated by the initial spit of JibrieniLetea-R˘aducu-Ceamurlia-Caraorman-S˘ar˘aturile-Peris, or-Lupilor [33]. The RazimSinoie Lagoon Complex to the south is a particular unit, composed of diverse large brackish water lagoons separated from the BS by juxtaposed beach-ridge formations [33, 34].

2.2 Natural and Anthropic Changes in the Danube-Danube Delta System The DR basin is Europe’s second-longest river (after the Volga) and has the largest catchment with a total area of 801,463 km2 . It is the world’s most international river basin, with 19 countries in its catchment. The DR ecosystem resources are valuable environmentally, historically and under socio-economical aspects, since they are sensitive and vulnerable to the cumulative impact of environmental and anthropogenic driven factors on the fluvial system [35]. Environmental factors include geomorphological structure, geological setting, seasonal differences in runoff volumes, weather conditions, water levels and flows, land cover etc. Among anthropogenic factors, the major threats are pollution from agriculture and industry, large human population and improper land use. Changes in riverine water and sediment discharge can be linked with several environmental and anthropogenic factors, but especially with man-made interventions, such as dams, channelization, in-stream mining, flow diversion, and land-use changes [36]. The upstream impoundment of large rivers, dams, as well as dike and/or canal construction have generated considerable changes to many delta ecosystems [37], causing, in general, a large reduction in the amount of sediment reaching deltas and triggered an erosion phenomenon of delta shorelines [13]. The character of the DR’s flow variability is mainly related to hydrological and climatic attributes, controlling the hydro morphology of the Danube fluvial system [27, 38, 39]. For example, the DR national average discharge is estimated at a rate of about 5.590 m3 /s at Bazias, -km 1072 (Danube entrance on the Romanian territory) up to 6.510 m3 /s at Ceatal Chilia—km 80 (Danube entrance on the DD territory) [40]. The extreme river flow values are fluctuating from: 15.540 m3 /s for peak discharges (when the river reaches its highest flow) to 1.610 m3 /s, for low flow [41]. The hydrologic regime of the DR is also influenced by the regional precipitation pattern [42]. The DR is the largest river and waterway in Romania, including important water-related protected areas for species and habitat protection. The impact of anthropogenic modifications of the DR Basin, and especially the construction of the major dams Iron Gates I and II at the border of Romania and Serbia (1964– 1982), was the main cause of diminished alluvial input and imbalance of the coastal sediment budget [17]. This has resulted in a decrease of coastal sediment volume by more than 30–40%, and currently, the Danube total average is not greater than 35–40 million t/yr., including 4–6 million t/year that is sandy material [33, 38]. Since 1970, the sandy sediment contribution from the DR input into the coastal sediment

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budget was considerably lower. It is estimated that the origin of the current sediment load of the Danube is represented by the subaerial eroded areas of the river course by mass movement and weathering. Suspended sediments and a small amount of sandy material are also the source that the upland erosion of tributaries could supply, as well as river bank erosion processes [33, 38]. Before reaching the BS, the DR is dividing into three main distributaries i.e., Chilia, Sulina and Sf. Gheorghe that are interconnected thorough a chain of lakes, ponds, marshlands, reed islets, streams and canals. Thus, several interdistributary depressions of fluvial-dominated delta plains are connected, forming a shallow-water delta hydrographic system. The major engineering works in the DD started in 1857, with the Sulina meander cutting programme [43] to shorten the distance between the Danube harbours (Braila, Galati) and the BS. The cutting of the Danube distributaries (Sulina and Sf. Gheorghe) altered the hydrologic conditions, shifting the water and sediment discharge distribution in all three distributaries, with Sulina and Sf. Gheorghe taking more water in time, from Chilia, leading to the current distribution Chilia - 50%; Sulina - 20% and Sf, Gheorghe - 30% and changing bed-sediments grain size and distribution. Nowadays, along these two distributaries the bed-sediments are dominated by fine sand and silt, while on Chilia the bed-sediments are fine sand, silt and clay [44, 45]. The hydrological regime of the DR is the main controlling factor for the entire deltaic ecosystem function. The fluvial-lacustrine hydrology dynamics significantly fluctuates as a consequence of the seasonal and interannual variability of the river and lake water flow and transport with periodical water flows under reed beds [46]. Subsequently, the spatio-temporal variations of the hydrological status may affect aquatic ecosystems (phytoplankton and zooplankton associations, aquatic plants, fish etc.) [31, 47]. The water distribution network was impacted as a result of the hydro-technical works, performed especially in the second half of the twentieth century, necessary for the establishment of agricultural polders, reed harvesting, forestry, fishing activity and navigation. The impairments are related to spatial and temporal distribution patterns between the main tributaries and the secondary network, including canals, inland waterways and lakes across the delta [22, 48, 49]. Human interventions into riverinedeltaic environments led to the disappearance of some natural channels and creation of man-made canals. Some of the changes that have occurred both in nature and as a result of man’s interventions are reflected in impaired functioning of deltaic-lagoon ecosystems environmental factors, as depth, velocity, bed-sediments and siltation, temperature, water chemistry and habitats [50–52]. Furthermore, the environmental issues are related to the impact of the hydrotechnical works on the lagoon complex Razim-Sinoie (canal deepening and dredging, configurations and control of the flow regime, including the two inlets - Periboina and Edighiol that provide a connection between the sea and the lagoons). These settings transformed a salt water lagoon into a fresh water body [53], significantly affecting the existing flora and fauna. Then, the interruption of the water exchanges between the Razim and Sinoe lakes (during the 70s) appears to be related to the long residence time, nutrient pollution and salinity [54]. In addition, the effects of the closing of the former inlet Gura Portit, ei have been mentioned as responsible for the occurrence of coastal erosion [55, 56]. Generally, downstream, the sediment load carried by the river shapes deltas and transfer fresh

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water and terrigenous sediment [57], including organic matter and nutrients to the coastal environment that are essential for marine ecosystems [58].

2.3 Danube Delta Lakes—Sinks for Natural and Anthropic Changes The DD lakes are flood plain lakes [31], located between the three distributaries of the Danube, a total of 300, with a size varying from 14 to 4350 ha [23]. As described previously, they are directly connected to the Danube through a vast network of channels and canals. The water level is variable in a year, depending on the river pulse [23]. Most of the lake sediments of the delta plain consist of silts (>65%), fine sand (6–15%), clay (20–30%) and shell fragments (2–4%) [59]. They are significantly bioturbated as a result of the biological activity of annelid worms, insect larvae (mainly chironomids) and mollusks [60]. In recent decades, all delta lakes suffered from eutrophication, which was most intense in the 1960s to the 1980s, due to anthropogenic input of phosphorous and nitrogen [31]. DD lakes were classified into three main categories, taking into consideration hydrogeomorphology and water quality, composition and abundance of plankton, aquatic vegetation and the fish community. Type 1 lakes are large, with a sandy-silt substratum and, turbid waters (e.g., Lacul Rosu, Merhei), type 2 lakes are well-connected to the channel network, have a clayey substrate and clear water (e.g., Fortuna), type 3 lakes are isolated, with organic load and clear waters [31]. The water turbidity is caused by the presence of suspended solids (mineral and detritus) and phytoplankton biomass, with an equal contribution, and is subjected to a strong seasonal variation [31]. A supervised classification of the delta lakes was made with Landsat-TM images. This shows that most of the large lakes (e.g., Uzlina, Fortuna, Matita, Merhei, Rosu) have turbid waters [61] but also that there is a gradient of turbidity, probably related to the presence/absence of vegetation [46] at local scales and the connectivity to the water network. The classification cannot distinguish between mineral or algal turbidity, but it was found that there is a positive correlation between these factors [31]. A recent analysis on a time frame of two years [61], revealed a seasonal variation of turbidity inside the DD and in the coastal plume: • During winter high levels of turbidity characterize lakes inside the delta, even those not directly connected to the hydrographic network, due to wind-induced resuspension of bed-sediments; • Spring season brings the peak hydrological discharge which influences the turbidity in only the lakes directly connected to the main distributaries, and most lakes present clear waters. Spring represents a transition period for both the lakes inside the delta, induced turbidity decreases; • In the summer river-induced turbidity decreases, but some lakes start to present high turbidity levels since June, coinciding with phytoplankton growth;

38

I. Catianis et al.

• During the fall, some lakes present the same turbidity patters as for summer, and some other lakes, more isolated ones, have higher turbidity levels. Generally speaking, turbidity in DD lakes is influenced by the water discharge and hydrologic connectivity, presence/absence of macrophytes and re-suspension processes caused by wind stress [31, 46, 61]. This study considered several areas of investigation throughout the deltaic-lagoon region (Fig. 2), aiming to provide an overall assessment of some trends related to recent sedimentation and to identify natural and anthropogenic contributions. The areas considered for this study are positioned from west to east, on the upstream to downstream areas, in relation to the gradient of the longitudinal distribution of the DR flow and sediment input. The DD acts as an intermediary between the river that brings

Fig. 2 Location of the studied lakes and bays/lagoons in the delta complex (Base map: Landsat 2000 images)

Danube Delta Lakes as Sinks for Natural …

39

alluvial sediment from the upstream and transfers that sediment through the hydrographic network (i.e., distributaries, channels, and lakes) closer to the sea. Changes in the water and sediment that occur in highly dynamic sedimentary marine environments also impact the DD lakes, depending on their setting [62]. This study investigates a series of lakes belonging to different depositional environments, as avandelta, fluvial-delta plain, fluvio-marine delta plain, delta front and lagoons (Fig. 2). A. Avandelta. The subaqueous part of the delta (shallow avandelta) is predominantly covered by freshwater and its geomorphic and sedimentary characteristics are controlled by the DR changes, being located in the free status of flooding [63]. The Somova - Parche¸s hydrographic unit is situated in the pre-deltaic area, upstream of the entrance of the DD (before Tulcea), and is more or less under the direct influence of the DR. The Somova - Parche¸s unit receives considerable freshwater inflow from the DR, particularly during spring, at high waters. A series of lakes as Gorgonel (176,4 ha), Rotundu (229,2 ha), Telincea (188 ha), Parches, (209,4 ha), Ivanova, Morun, Ciorciovata, Babele (69 ha), Petica, Somova (169 ha), Câs, la (153 ha) and Gâsca belong to this unit. Particularly, Rotundu L. is representative for the study and conservation of biocenoses adapted to large amplitudes of the flood wave and the production of cyprinids (families of freshwater fish). Similarly, Gâsca L., represents the protection zone for freshwater species. In this study, the following lakes were selected for being investigated: Parches, , Babele, Petica and Somova (Fig. 2). B. Fluvial delta plain (western - central part) - Sireasa - S, ontea - Fortuna Depression. This hydro-morphological unit is characterized by diverse hypsometry and genesis. Generally, the geomorphic and sedimentary features evolved under the influence of fluvial circumstances. The Sireasa-S, ontea-Fortuna depression is located between Chilia and Tulcea distributaries. The secondary hydrographic network is represented by several waterways as Sireasa, S, ontea, Olgut, a, Stipoc,” Mila 36 , P˘ap˘adia Veche and P˘ap˘adia Nou˘a Cnls. [38]. Within this unit, various lakes were taken into consideration for this study as Cutet, chi (Lacul cu Cotet, e), Babint, i, T˘ataru and T˘at˘arciuc (Fig. 2). These lakes are characterized by low hydrodynamic conditions, although locally generated water influxes from waterways may induce episodic agitation. Shallow lakes permit light to diffuse to the lake’s bottom, and aquatic vegetation is highly developed. From the central fluvial delta plain, the Fortuna L. (977.5 ha) was also investigated (Fig. 2). This lake is located in an area actively influenced by the river input. Fluctuations of considerable quantities of alluvial materials are transported by the Sulina distributary and several waterways (Crânjal˘a Cnl., Mitchina Cnl., S, ontea Cnl., Fortuna 1 Cnl., Fortuna 2 Cnl., and Fortuna 3 Cnl.). Bottom currents influenced terrigenous materials brought by the river which were reworked and deposited in the form of a microdelta that evolved in the southern part of the Fortuna L., as a result of Crânjal˘a Cnl., alluvial supply [64]. Over the last decades the supply of Crânjal˘a Cnl., was suspended for many times [65] and has been found to have an abnormally high level of silt deposits. This has not only inhibited the flow of the canal, but the intermittent closing and opening of the canal has also contributed to considerable depositions of the organic components due to the changes in hydro sedimentary regime. It is known that many deltaic lakes would have historically

40

I. Catianis et al.

gone through siltation and clogging during extended droughts or accumulation of abundant aquatic vegetation. C. Fluvial delta plain (northern - central part) - Lopatna - Matit, a - Merhei Depression. Under morphodynamical aspect, the Lopatna - Matit, a Merhei unit is characterized as a weakly clogged lacustrine depression area [22]. This unit is situated between Chilia (Cernovca distributary and Chiliei Grind), in the northern part, and Sulina distributaries (the big” M” of the Old Danube distributary), in the south. The most important lakes are represented by Merhei (1137.47 ha) and Matit, a (641.83 ha) which are the largest of the complex [66, 67], as well as Babina (427.35 ha), Bogdaproste (400.19 ha), Trei Ozere (433.5 ha), and other lakes, but smaller [68]. Small lakes are currently covered by rich submerged vegetation or highly clogged. The water circulation of lakes is maintained by several waterways (e.g., Eracle, Lopatna, Dovnica, R˘aducu, Bogdaproste, Suez, R˘ad˘acinoasele, Stipoc, Sulimanca and Ro¸sca) [38]. This area is located further away from the main distributaries of the DR, thereby is not considerably influenced by the water and sediments provided by the fluvial intake. From this depression, the following lakes were investigated: Babina, Matit, a, Merhei, R˘ad˘acinos, Trei Ozere and Bogdaproste (Fig. 2). D. Fluvial delta plain (central part) - Rusca - Gorgova - Uzlina Depression. The area of Rusca - Gorgova - Uzlina is located in the morphogenetic type of the depressions’ area of the Fluvial Delta [22] between the Sulina and Sf. Gheorghe distributaries. This interdistributary subunit includes numerous small and large lakes (110), i.e., Fastic, Cuzmânt, u Mare, Rotund, R˘ad˘acinos, Gorgov˘at, , Gorgova (1377.5 ha), Potcoava, Potcoava Mare, Obretinciuc, Uzlina (468 ha), Isacova (1101 ha), Pojarnia, Chiril, Durnoliatca etc. The main waterways are represented by the Litcov Cnl., Perivolovca Ch., Ceamurlia Cnl. [38]. From this unit the following lakes were investigated: Uzlina, Isacova, Is˘accel, Pojarnia, Chiril, Durnoliatca and Gorgova (Fig. 2). E. Fluvio-marine delta plain (eastern part) - Lumina - Ros, u Depression. The lower fluvio-marine delta plain lies within the interaction of river and marine environments, in the fluvial to marine transition zone. This unit that extends between the Letea Caraorman-Crasnicol marine levees (west), and the coast (east), includes an important lacustrine complex: Ro¸su - Ros, ulet, - Puiu - Lumina [28]. These lakes are characterized by shallow depths and a rich submerged vegetation. The secondary hydrological network, which is situated between Sulina and the Sf. Gheorghe distributaries, is quite well represented, being in connection with the Sulina distributary (e.g., Caraorman Cnl., at Mile 14, V˘atafu Cnl., at Mile 7, Busurca Cnl., at Mile 2, Pesc˘arie Cnl.), as well as with the Sf. Gheorghe distributary (e.g., Erenciuc, Ivancea and T˘ataru Cnls.). The drainage outlets that provided the water discharging from the depression towards the sea are represented by Împu¸tita and Sondei Cnls. [38]. Nowadays, these canals are closed by the Sf. Gheorghe - Sulina roadway. From this unit the following lakes were investigated: Ros, u (1445 ha), Ros, ulet, , Puiu (86 ha), Iacub, Puiulet, , Lumina (1367 ha), and V˘atafu (Fig. 2). F. Delta front - transitional area. The delta front environment is characterized by the area of interaction located at the mouth of the Chilia, Sulina and Sf. Gheorghe distributaries, and the zone where the marine factors (wind, waves, under water

Danube Delta Lakes as Sinks for Natural …

41

sedimentation) play an important role in reworking both allogenic and authigenic sedimentary material. For this study, Musura Bay and Sahalin Bay were selected (Fig. 2). Musura Bay is a shallow semi-enclosed brackish water body (1–5‰), with a maximum water depth of 1–2 m, located in the delta front [69], specifically in the area where Chilia and Sulina distributaries discharge into the BS. The evolution of the Musura Cnl., and Musura Bay is shaped by human interventions. During the first half of the twentieth century, the bay had a wide opening towards the sea (13 km) and depths over 12 m and harboring a marine biocenosis. Recently, the cumulative effects of the alluvial deposition, the rapid advancement of Chilia secondary delta in the northern part of the bay, including the construction of a new channel (9 km) at the mouth of Sulina distributary [69], led to a progressive narrowing of the bay and its decreasing depth from the mouth. In 2005, the opening area towards the sea recorded 5 km, while the depth decreased to 2 m [70]. The specific marine environments and recent evolution of the Musura Bay was marked by intense modifications of the natural configuration of its geomorphology, initiating a gradual shift from marine gulf stage to a half-enclosed bay, with many freshwater characteristics. Mostly decreasing trends of water level, salinity (i.e., 1942-12‰; 2005-0.18‰), in relation to the mentioned geomorphological changes, increased the availability and proliferation of the typical freshwater vegetation, generating structural and functional shifts in plankton species diversity [70–72]. In the future, it is predicted that the fate of the bay shall be the sealing-off as a result of the rapid siltation [43]. Sahalin Bay is a shallow marginal body of water (about 1–2 m), situated in the place where the large flowing body of the Sf. Gheorghe distributary empties into the BS, south of its mouth. A barrier island, i.e., Sahalin Island, was formed by the faster supply of alluvial sediment and the marine up drift sediment input, being currently in a continuous expansion [33]. Sahalin Bay has an opening to the BS, but is also protected from it by this sandy barrier, which today measure 19 km in length. Several kilometers (in length and width) cover the low salinity ecosystems (0-13.5‰), between the initial shoreline and the barrier island. Long-term behavior of the Sahalin Bay was controlled by a number of dynamically complex and competing physical processes occurred in the recent past. The lake-forming process, by merging the Sahalin Island with the coast, continues even if the island is now a peninsula (split) [73]. The evolution of Sahalin Bay is driven by cross-shore and/or longshore morpho dynamic processes or their interaction, bringing the continuous elongation of the spit (in average 100– 140 m/year). Sediment availability is a significant parameter controlling the spit’s winnowing and reworking mouth-bar deposits, but the main cause of spit and barrier island landward lateral migration (over a 20 m/year on average) is the overwash process [74]. G. Razim - Sinoie Lagoon Complex. The Razim-Sinoie Lagoon Complex is the second component of the DD, placed to the south of the DD itself, and the northwestern coast of the BS, where the freshwater and saltwater are found in the same vicinity. The total surface area is about 1145 km2 , of which the lagoons and limans spread out over 863.4 km2 . Actually, the lacustrine complex includes a chain of former salt lagoons turned into brackish lakes - Razim (41,400 ha and a maximum depth of 3.5 m [66, 75], Golovit, a (11,870 ha), and Zmeica (5460 ha) and

42

I. Catianis et al.

a coastal lagoon with two artificial inlets Sinoie Lagoon (17,150 ha), in association with other lakes - Babadag (2470 ha), Histria (560 ha), Nunta¸si-Tuzla (1050 ha), wetlands, barrier beaches, and sandbars. The lagoon complex is mostly supplied with fresh water from the Sf. Gheorghe distributary by Dunav˘at, , Dranov, Lipovenilor and Mustaca waterways. In the south, the complex is interconnected through Sinoie L., with the BS by Periboina and Edighiol outlets, which are mechanically opened/closed. The operation of opening/closure cycles resulted in the deterioration of water, sediment and ecosystem quality [53]. Setting the scale of the historical regional changes and processes that took place in this mixed wetland lagoon complex aroused the early interest of many researchers for a long time and is found in several specific scientific works [19, 20, 76–80]. Other relevant studies expose results from a variety of ecological and environmental perspectives related to this wetland system which is very sensitive to large-scale changes acting as an indicator ecosystem for anthropogenic perturbations [81–85]. The structural and geomorphic evolution of the coastal lagoon complex, primarily, a marine bay (e.g., the former Halmyris Gulf) became progressively isolated from the sea by the sand accretion, redistribution of these sandbars and associated alterations of their geomorphological configuration [86]. Then, the impact of dams and hydro technical works constructed in the past along the DR and its distributaries, and at the mouth of the Sulina distributary and the inlet of Gura Portit, ei led to an alteration on coastal processes related to erosion and accumulation, resulting an unbalanced sediment budget [87]. Roughly, 60 percent of the entire deltaic coasts are attributed to erosion, and the remaining 40 percent is allocated to accumulation [88]. For this study Razim, Golovit, a, Zmeica, Sinoie, Babadag and Histria (Fig. 2) were investigated. Razim is the largest freshwater lagoon in Romania, formed on the BS coast due to the enclosing, by the wave-dominated coastal sedimentary formations, of the ancient Gulf of Halmyris. Local hydrotechnical works performed in the past decades for intensive fish-farming resulted in significant impairments or interferences of the natural processes, the water balance, the ecological balance, and the loss of areaspecific habitats. Before the embankment dams that were built in the 1980s, the lake communicated with the BS by Gura Periteas, ca and Golovit, a waterways. These migration routes were very important for marine fish, since the lake provided the best habitat for fish growth and production. Receiving fresh water from the DR through Sf Gheorghe distributary (i.e., Dranov and Dunav˘at, Cnls.) the lake became, after closing its mouths, a fresh water lake. Golovit, a is the second-largest lake of the lagoon’s complex. It is connected to the Razim L., on the northern part of a channel of 3.1 km wide, to Zmeica L., on the southern part by three narrow channels, and set apart from the sea by a narrow sand barrier (spit or bar). Until the 1970s, this lake communicated with the BS through a natural restricted outlet, i.e., Gura Portit, ei, that was artificially closed [89]. As well, communicates with Sinoie L. by Golovit, a-Sinoie Canal, known as “Cnl. 5”. Zmeica is the third component lake of the lagoon’s system, being located at an altitude of 1 m above sea level. It is connected to the Sinoie L. by Zmeica-Sinoie Cnl.

Danube Delta Lakes as Sinks for Natural …

43

Sinoie is a lagoon located close to the BS. Due to its position within the complex and the great distance from the mouth of the Dunav˘at, and Dranov Cnls., (which supply fresh water), the Sinoe L., has a high salt concentration of about 15 g/l. Babadag is a lake located west of Razim L., communicating with it by Enisala Cnl. The water supply is mainly assured through two canals, and the water drainage from the lake is made through a single canal to the Razim L. Histria is a marginal lake with a low water concentration (isolated lake) and is located in the southeastern part of the Sinoie L. As a consequence of the semi-arid climate conditions, there has been a progressive accumulation of salts; thereby the lake has balneal-therapeutic characteristics.

3 Materials and Methods Sediments are largely separated into two generic clusters, allochthonous sediment and allochthonous sediment, within continental (fluviatile), transitional (deltaic/lacustrine) and coastal subaquatic environments. Allochthonous sediments reflect the combination of various disaggregated particles (by weathering and recycling products of variable rock types and erosion) that have been transported (by the action of wind, water or gravity) to a site of deposition. Autochthonous sediments are generated in situ (locally) and consist of a high biogenic content such as: organic-rich sediments (conservation of plant and animal yield production), biogenic sediment such as carbonate (e.g., biogenic debris) and silica (e.g., endogenous diatoms).

3.1 Sampling of Bed-Sediments Bed-sediment sampling was performed during several field campaigns with the R/V “Istros” of the National Institute for Marine Geology and Geo-ecology–GeoEcoMar, in different hydrological regimes (high water and low water). Sediment samples were collected using a Van Veen Grab Sampler. Taking into consideration that the natural sedimentation rate ranges from 0.005 to more than 1 cm/year, and increases to 20 cm/year in reservoirs [90], the top 5 cm of surface sediment (approximately 15–50 years) was collected for measurements. The visual description of the bed-sediment samples was performed on-board the R/V “Istros”. The description was related to the structure, texture, grain size, sorting, stratification, the main lithoclasts (clay, mud, silt, sand, gravel), bioclasts (shells and detritus, faunal and vegetal remains), as well as color, odor and appearance etc.

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3.2 Laboratory Analyses To perform a general classification of the lacustrine sediments collected from different inter-distributary areas of the DD, the Loss On Ignition method (LOI) was used [91–93]. Sediments are composed of different phases, such as mineral particles and organic matter. Freshwater and marine sediments (porous, soft or lithified) consist of three major component parts i.e., organic matter, carbonate and siliciclastic sediment, and which embodies their solid fraction [94]. LOI is the most common approach for determining the total organic matter (TOM%), total carbonates (CAR%) and siliciclasts content (SIL%) from sediments, obtained from the weight loss [95, 96]. Sediment samples are initially dried (105 °C) to combust the moisture content (%) [97, 98] and then are subjected to sequential heating and measuring weight loss between heating stages (Loss On Drying method - LOD). The loss in mass at each of these stages provides an assessment of the total organic matter (TOM%), by calcination at 550 °C [91, 99–102], and respectively the mineral residue (SIL%) by ignition at 950–1000 °C [101, 103]. The sediment’s carbonate content (CAR%) was roughly estimated by heating the sediment to 950 °C [104]. The LOD/LOI results are expressed as percentages of the total organic matter, total carbonates and mineral residue obtained from the total original dry sample weight. The final results of the main lithological components (TOM%, CAR% and SIL%) were plotted using the contouring and surface mapping features of a specific software [105] and the interpolation of data in the maps was performed by the Krigging method of gridding.

4 Results and Discussions 4.1 Macroscopic Features of the Bed-Sediment Samples The sediments supplied by the DR are transported, distributed, deposit, and/or resuspended under various lacustrine or marine hydrodynamic conditions. The sediment yield and hydrodynamic processes are variable and significantly impact aquatic sediments, especially the re-suspended fine sediments and coarse sediments within the deltaic-lagoon area. The sediment samples reflect an intermixing of different components, having only one major component group i.e., very high organic matter contents (more than 50%), moderately siliciclastic material content (around 35%), including different amounts of carbonates (about 10–15%). No sediment sample had sufficient lithoclasts or mineral particles (detrital sand size or silt-size fraction) to acquire a sediment name. If sand, silt, or clay is >50% of the sediment or rock, the principal’s name is attributed according to the relative percentages of the various size groups (sand, silt and clay) when designed on a classification chart [106]. Detrital components may include grains ranging from coarse sand to fine sand through siltsized particles of various minerals. It is also assumed that clay is present in almost all sediment samples. The origin of these particles may be lithogenic, in some measure

Danube Delta Lakes as Sinks for Natural …

45

eolian, partially as a result of suspended sediment transport and partly authigenic (parent material). The physical–chemical attributes of the bed-sediment samples evidenced considerable distinctions linked to environmental conditions and fluctuations of the main lithologic composition (TOM%, CAR%, SIL%). Generally, fine and coarse organic material was found in sediment samples collected from areas characterized by low hydrodynamic conditions and confined depositional environment. Instead, the coarse siliciclastic material was found in sediment samples collected from areas characterized by strong hydrodynamic conditions and erosion environment. As well, it was noticed, variations in colors, odors and textures depending on the sampling sites. Dark-colored sediments suggested mostly elevated organic compounds, as opposed to light-colored sediments, revealing lower levels of organic components or, possibly, substantial contents of carbonate materials, or soluble salt contents. Wide differences in particle size distributions were also observed, varying in different proportions, from silt and clay, to sand (fine, medium or coarse). Fine sediments (silt and clay), are characteristic of low hydrodynamic conditions, while sand is representative of relatively high hydrodynamic conditions (flowing waters, or, marine environs). Within this study, the sediment samples were mostly reported as greenish brown or brown - blackish, muddy-like (silt and clay), occurring generally in zones characterized by low hydrodynamic conditions (middle of the lake, vegetated edges). A large part of the collected sediment samples consisted of organic muds (fine and coarse organic matter), derived from triturated vegetal particles, live and dead rhizomes, fine roots, large leaf debris. The rest of the samples are represented by sediment material of light brown or dark grey color (fine-medium grained, clastic composition) collected from area characterized by active hydrodynamic conditions. A brownish pellicle is formed on the surface of sediments (top 1 cm) due to in situ microbial activity or chemical oxidation. As well, a relatively high proportion of coarse carbonate fragments with clasts and shell debris is present at the surface of sediments. The freshwater macrobenthic communities are represented by different species of gastropods (Lithoglyphus naticoides, Viviparus viviparus, Planorbis planorbis, Limnaea stagnalis, Valvata piscinalis, Radix ovata), bivalves (Dreissena polymorpha, Unio pictorum, Anodonta cygnea), polychaete, oligochaete worms and insect larvae (Chironomidae sp.). Brackish water environments sustain a mix of specific fresh and marine communities as species of gastropods, bivalves (Cardium edule, Corbicula fluminea, Limnocardiidae sp., Anodonta cygnea, Unio pictorum, Dreissena polymorpha), polychaete, oligochaete worms, insect larvae and small marine crustaceans (Cumaceae sp.).

4.2 Data Analysis, Interpretation and Evaluation A quantitative compositional analysis of recently accumulated sedimentary material using LOD and LOI Method was obtained. The general estimation was reported as the percentage difference between the total dry weight of the sample minus the

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experimentally determined organic matter, carbonates and siliciclasts contents (in weight percent). Moisture content (WC%) and dry residue (DM%) are two basic constituents that are measured more accurately through mass and volume determinations, from field-moist samples. Naturally, aquatic sediments are characterized by exceedingly high values of water content due to the variability of lacustrine sediment physical properties (bulk density, particle size, organic content). Consequently, total water content fluctuates from intermediate values (30–50%) in minerogenic sediments to exceptionally high values (95–99%) in biogenic deposits [107]. Organic matter (TOM%) is a significant component of recent aquatic sediments, serving as an indirect environmental indicator to characterize the status of different source areas, as allochthonous inputs (materials arriving from outside the aquatic system) and autochthonous production (in situ of the aquatic system). Several research findings provide scientific evidenced for allochthonous origin (changes in discharge regimes, upstream sediment supply, windblown particle transport), as well as autochthonous origin (in-lake productivity processes) [108–111]. Aquatic sediments can become the organic matter sink, dictating the dynamics along the water column and specific local sedimentary environment [112–114]. The results acquired in this research were compared to those obtained from a general classification of the organic matter content of soil [115–117], where two groups were mainly separated in organic deposits (about ≥15–30% organic compound) and mineral deposits (≤15–30% organic compound). Total amounts of carbonates (CAR%) includes inorganic carbonates (i.e., aragonite and calcite), as well as calcareous biogenic debris [118]. The carbonate content of sediments serves as an integrated palaeoecological/biogeochemical proxy for the environmental evolution of the aquatic system [119–121]. The results obtained in this study were compared to the classification proposed by [122], that established three main categories of sediments based on calcium carbonate (CaCO3 ) content: noncarbonated sediments (≤10%), low calcareous sediments (10–30%) and calcareous sediments characterized by high carbonate content (30–50%). The siliciclastic material (SIL%) (fragmented materials that derive from weathering of pre-existing rocks) serves as a paleoenvironmental indicator [123, 124] associated to exogenous inputs of sediments (transported into aquatic systems from upstream and/or external sources), or to endogenous inputs of sediments (geological setting, the erosion of banks etc.).

4.3 Spatial Distribution of the Main Lithological Components in Bed-Sediments The results related to the main lithological components (TOM%, CAR%, SIL%) and physical parameters (WC%, DM%) showed several interesting variations regarding the investigated aquatic environments. These results are synthesized in Table 1.

Lake

Parches,

Babele

Petica

Somova

T˘ataru

T˘at˘arciuc

Cutet, chi

Babint, i

Fortuna

Matit, a

Merhei

Babina

Bogdaproste

Trei Ozere

R˘ad˘acinos

Uzlina

Isacova

Is˘accel

Pojarnia

Nr crt

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

54.54

70.75

72.28

49.81

36.96

54.26

72.09

59.41

51.66

75.84

70.70

38.06

70.59

66.13

51.90

52.17

58.20

83.24

81.12

82.36

84.29

90.34

82.28

83.58

80.08

85.64

90.61

89.74

91.70

84.07

81.52

76.65

78.82

81.29

77.85

86.59

89.26

90.29

71.95

72.46

82.49

72.08

61.84

71.29

77.98

78.69

77.77

84.35

76.91

67.33

74.35

73.54

70.58

64.46

69.16

86.13

83.13

3.76

3.46

1.28

4.69

1.78

3.50

4.25

1.19

5.40

3.56

6.42

2.55

5.28

4.99

3.10

3.70

3.26

2.43

2.57

11.59

13.21

16.46

12.95

17.36

20.30

18.39

19.60

15.60

15.77

20.33

9.83

10.33

16.67

19.16

11.78

8.03

8.89

11.08

8.38

5.96

11.18

8.74

10.96

11.33

7.94

11.92

9.82

11.24

10.98

7.67

7.02

8.18

13.72

8.33

5.01

7.18

6.54

Mean

SIL (%)

11.99

8.34

5.22

14.64

10.94

6.85

0.70

4.86

3.79

6.58

9.52

15.40

14.95

14.52

15.53

10.15

7.66

7.13

13.88

Min

20.86

21.03

40.01

54.51

32.94

21.08

38.55

40.50

13.10

20.52

52.89

22.90

27.90

32.92

30.37

31.45

10.97

11.14

34.39

Max

19.16

11.54

16.74

29.43

17.75

10.70

13.38

10.31

5.83

11.85

21.69

17.98

19.44

21.24

21.82

22.51

8.87

9.69

21.51

Mean

29.21

11.20

9.03

16.47

29.03

8.20

16.23

5.87

12.53

8.76

6.92

12.57

12.95

14.00

28.84

4.38

9.47

3.12

8.10

Min

49.20

22.52

34.14

36.33

38.88

33.83

46.78

22.37

18.86

22.90

29.61

97.16

25.22

54.29

51.95

17.50

19.43

11.85

14.23

Max

35.19

18.33

19.09

24.62

35.21

23.06

26.38

11.50

15.85

14.15

13.21

22.53

18.58

26.26

36.82

10.37

13.45

6.89

10.75

Mean

WC (%)

Max

CAR (%) Min

Min

Mean

TOM (%)

Max

Physical parameters

Lithological parameters

50.80

77.48

65.86

63.67

61.12

66.17

53.22

77.63

81.14

77.10

70.39

2.84

74.78

45.71

48.05

82.50

80.57

88.15

85.77

Min

DM (%)

64.81

81.67

80.91

75.38

64.79

76.94

73.62

88.50

84.15

85.85

86.79

77.47

81.42

73.74

63.18

89.63

86.55

93.11

89.25

Mean

(continued)

70.79

88.80

90.97

83.53

70.97

91.80

83.77

94.13

87.47

91.24

93.08

87.43

87.05

86.00

71.16

95.62

90.53

96.88

91.90

Max

Table 1 Percent by mass concentration of the lithological parameters (TOM, CAR, SIL) and physical parameters (WC, DM) in the superficial sediment samples of the investigated ecosystems

Danube Delta Lakes as Sinks for Natural … 47

Lake

Chiril

Durnoliatca

Gorgova

Ros, u-Ros, ulet,

Puiu

Iacub

Puiulet,

Lumina

V˘atafu

Musura Bay

Sahalin Bay

Razim

Golovit, a

Zmeica

Sinoie

Babadag

Histria

Nr crt

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

Table 1 (continued)

4.92

13.16

0.91

24.63

29.37

15.62

1.34

12.42

71.43

59.50

48.46

23.92

49.13

24.71

37.96

62.88

72.16

77.36

64.33

68.27

74.32

62.87

44.90

39.22

94.68

96.58

92.38

81.33

72.14

65.30

80.50

83.62

57.28

49.36

39.70

40.21

58.24

44.44

23.96

23.21

86.74

85.42

83.84

65.45

62.85

50.84

67.48

77.00

89.48

5.53

5.45

7.06

8.13

7.08

8.82

6.17

10.52

1.49

1.41

2.36

5.69

17.01

12.63

5.64

6.02

1.75

49.60

52.05

43.25

30.12

14.57

36.38

14.10

13.81

5.38

15.89

12.68

10.56

26.73

50.86

23.19

9.31

4.53

Max

Mean

10.35

10.09

16.41

18.43

10.14

15.32

9.41

12.53

3.16

7.32

5.96

7.58

21.66

29.61

13.94

7.40

2.73

18.70

16.24

26.21

23.61

18.31

24.52

48.93

46.97

3.84

2.01

3.92

11.58

10.85

3.56

10.44

10.37

4.92

Min

Max

79.49

78.62

80.05

54.71

57.13

64.83

86.75

74.86

24.52

33.05

44.13

65.74

25.20

51.04

46.26

30.42

10.42

Mean

32.37

40.56

43.89

41.36

31.62

40.25

66.63

64.25

10.09

7.26

8.31

26.97

15.49

19.55

18.58

15.60

7.78

9.43

4.97

17.08

10.80

7.20

7.32

17.12

20.69

17.12

6.48

7.89

6.51

19.33

12.50

15.57

21.94

17.24

Min

23.72

14.07

41.46

29.76

12.58

16.81

24.26

33.54

30.22

28.86

28.78

32.90

51.49

56.72

42.58

38.35

24.50

Max

15.75

7.53

25.40

18.04

9.88

12.22

20.74

26.26

21.67

14.35

14.61

16.17

32.00

30.87

22.24

31.52

21.76

Mean

Min

91.79

Mean

Min

Max

WC (%)

87.47

Physical parameters

TOM (%)

SIL (%)

CAR (%)

Lithological parameters

76.28

85.93

58.54

70.24

87.42

83.19

75.74

66.46

69.78

71.14

71.22

67.10

48.51

43.28

57.42

61.65

75.50

Min

DM (%) Max

90.57

95.03

82.92

89.20

92.80

92.68

82.88

79.31

82.88

93.52

92.11

93.49

80.67

87.50

84.43

78.06

82.76

Mean

84.25

92.47

74.60

81.96

90.12

87.78

79.26

73.74

78.33

85.65

84.52

83.83

68.00

69.13

77.76

68.48

78.24

48 I. Catianis et al.

Danube Delta Lakes as Sinks for Natural …

A.

49

Avandelta

The analyses carried out on samples taken from lakes as Parches, , Babele, Petica and Somova are presented below. For instance, WC% showed slight variations within each sample, having values around maximum 19% (obtained from the dry weight of the sediment sample) (Table 1). The moisture content may be linked to water level fluctuations, climatic conditions and temperature profiles. Results obtained from TOM% contents were transposed as maps of the areal distribution (Fig. 3), that did not show remarkable differences between lakes. The spatial distribution maps showed that TOM% content was the most dominant component in bed-sediment samples, having values exceeding 50% of the dry weight of

Fig. 3 Interpolated spatial distribution maps showing the concentration of TOM% in bed-sediments of investigated lakes: Parches, (a), Babele (b), Petica (c) and Somova (d)

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the sample. These high-value contents are related to endogenous (underwater vegetation, aquatic organisms) and exogenous (vegetation on the shores of lakes) organic matter input. For such lakes weakly influenced by the DR input, the spatial distribution of the TOM% content lead to the assumption that the recent accumulation of sediment is predominantly controlled by the local environmental circumstances (geomorphology, geology and underwater topographical features). On the basis of results obtained from laboratory analyses (percentage of sediment organic matter), the investigated sediments were classified as organic sediments (≥15–30%), and subsequently as mineral sediments (≤15–30%). Analysis of the interpolated results of the CAR% content showed slight variations within each lake with relatively lower values (10% < CaCO3 ≤ 30%) (Table 1) (Fig. 4). The pattern of carbonate occurrence is related to local environmental

Fig. 4 Interpolated spatial distribution maps showing the concentration of CAR% in bed-sediments of investigated lakes: Parches, (a), Babele (b), Petica (c) and Somova (d)

Danube Delta Lakes as Sinks for Natural …

51

conditions. Apparently, the carbonate rich-sediment samples consist mostly of fine and coarse calcareous shell debris admixed in sediment (authigenic carbonates). Probably, such lakes, characterized by low hydrodynamic conditions and calm depositional environment facilitate opportune conditions for benthic communities, so their growth is not restricted by limitative factors. Furthermore, disseminated authigenic carbonates in sediments may be related to various factors present in the depositional area (chemical precipitation, recrystallization, mechanical erosion and abrasion of endogenous and exogenous carbonate fragments). On the basis of results obtained from laboratory analyses (percentage of sediment carbonates), the investigated sediments were classified as non-carbonated sediments (CaCO3 ≤ 10%), and subsequently, as low calcareous (10% < CaCO3 ≤ 30%). Generally, the results obtained from laboratory analyses (percentage of sediment siliciclasts) showed lower values for SIL% content (Table 1) (Fig. 5). Though,

Fig. 5 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: Parches, (a), Babele (b), Petica (c) and Somova (d)

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I. Catianis et al.

increased levels of SIL% were noticed in the locations with low organic matter content. In fact, these two variables (SIL% versus TOM%) have a strong negative correlation. The concentrations of the silica-rich sediment samples in different sectors of the lakes are linked to lacustrine parent material that in turn depends, directly or indirectly, to the matrix of the sediment, its susceptibility to erosion, resuspension or other physical characteristics. B.

Fluvial delta plain (western - central part) - Sireasa - S, ontea - Fortuna Depression

The analyses carried out on samples taken from lakes as T˘ataru, T˘at˘arciuc, Cutet, chi, Babint, i and Fortuna showed a significant variation of the obtained values. Regarding the WC% it was noticed that widely varied (Table 1), and in some samples, reached high values (e.g., Babint, i L.), exceeding 50% of the dry weight of the sample. The fluctuating values could be connected to physical properties of sediments (bulk density, grain-size, porosity). The TOM% content was influenced mainly by the abundant accumulation of the organic material. Corresponding spatial distribution maps of estimated sediment organic content (TOM%) were plotted and displayed layers with values exceeding 50% of the dry weight of the sample (Fig. 6). TOM% was the prevalent sediment component in the investigated samples, excepting the stations located near waterways which are characterized by strong hydrodynamic conditions that determines the alluvial deposition and erosion (i.e., Mitchina Cnl. - west of Fortuna L., and Crânjal˘a Cnl. south of Fortuna L.).

Fig. 6 Interpolated spatial distribution maps showing the concentration of TOM% in bed-sediments of investigated lakes: T˘ataru (a), T˘at˘arciuc (b), Cutet, chi (c), Babint, i (d) and Fortuna (e)

Danube Delta Lakes as Sinks for Natural …

53

Regularly, the maximum values of TOM% occurred in different sheltered sectors of lakes which are characterized by a passive water environment undisturbed by bottom currents, with very low sedimentary input and excessive development of emergent and submerged vegetation. These environmental circumstances can facilitate excessive endogenous deposition of organic material. On the basis of results obtained from laboratory analyses (percentage of sediment organic matter), the investigated sediments were classified as organic sediments (≥15–30%), and subsequently as mineral sediments (≤15–30%). The measurements of carbonate levels in the investigated samples showed relatively lower values (CAR%) (Fig. 7). The relative carbonate rich-sediment samples are mainly represented by fine and coarse calcareous shell debris admixed in sediment. The high degree of the carbonate content of the bed-sediments might indicate an endogenous source of carbonates (particle disintegration, particle reworking, dissolution of authigenic carbonates, precipitation, recrystallization etc.). On the basis of results obtained from laboratory analyses (percentage of sediment carbonates), the investigated sediments were classified as non-carbonated sediments (CaCO3 ≤ 10%), and subsequently, as low calcareous (10% < CaCO3 ≤ 30%). The sediment samples tested for siliciclastic content showed significant variation in distribution. The spatial distribution maps (Fig. 8) showed certain areas with the highest SIL% matter. These areas are related to different channels/canals which are characterized by active hydrodynamics.

Fig. 7 Interpolated spatial distribution maps showing the concentration of CAR% in bed-sediments of investigated lakes: T˘ataru (a), T˘at˘arciuc (b), Cutet, chi (c) , Babint, i (d) and Fortuna (e)

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I. Catianis et al.

Fig. 8 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: T˘ataru (a), T˘at˘arciuc (b), Cutet, chi (c), Babint, i (d) and Fortuna (e)

C.

Fluvial delta plain (northern - central part) - Lopatna - Matit, a - Merhei Depression

The analyses carried out on samples taken from lakes as Matit, a, Merhei, Babina, Bogdaproste, Trei Ozere and R˘ad˘acinos indicated a significant variability of the obtained values. The samples were characterized by a wide range of variation for WC% with some maximum values of almost 50% of the dry weight of the sample (Table 1). Most likely, the sediment matrices provide the retention of interstitial water. Likewise, TOM% content showed substantial variation in results (Table 1). The spatial distribution and relative abundance of organic matter (Fig. 9) displayed values exceeding 50% of the dry weight of the sample. The high degree of TOM% content might indicate an internal source of organic matter generated as a result of several in-lake productivity processes that furnish plenty of organic matter in this lacustrine depression. On the basis of results obtained from laboratory analyses (percentage of sediment organic matter), the investigated sediments were classified as organic sediments (≥15–30%), and subsequently as mineral sediments (≤15–30%). The CAR% content measured in the collected samples did not indicate significant variations in results (Table 1) (Fig. 10). The range of variations suggests that relatively higher carbonate contents occurred in some locations may have a biogenic provenance, including high productivity of underwater flora and fauna, macrofauna shell formations, and encrustations in certain lacustrine substrates. In function of the

Danube Delta Lakes as Sinks for Natural …

55

Fig. 9 Interpolated spatial distribution maps showing the concentration of TOM% in bed-sediments of investigated lakes: Matit, a (a), Merhei (b), Babina (c), Bogdaproste (d), Trei Ozere (e) and R˘ad˘acinos (f)

Fig. 10 Interpolated spatial distribution maps showing the concentration of CAR% in bedsediments of investigated lakes: Matit, a (a), Merhei (b), Babina (c), Bogdaproste (d), Trei Ozere (e) and R˘ad˘acinos (f)

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I. Catianis et al.

Fig. 11 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: Matit, a (a), Merhei (b), Babina (c), Bogdaproste (d), Trei Ozere (e) and R˘ad˘acinos (f)

results obtained from laboratory analyses (percentage of sediment carbonates) (Table 1), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, as low calcareous (10% < CaCO3 ≤ 30%). The investigated samples indicated relatively lower values of SIL% content (≤40% of the dry weight of the sample) (Table 1) (Fig. 11). The relatively silica-rich sediment samples were encountered in different sectors of the lakes, and could be linked to superficial deposits of underlying parent materials (unconsolidated mineral materials that mostly settle near the mouth of the channels or in other dynamic sectors of lakes). D.

Fluvial delta plain (central part) - Rusca - Gorgova - Uzlina Depression

The analyzes carried out on samples taken from lakes as Uzlina, Pojarnia, Chiril, Isacova, Is˘accel, Durnoliatca and Gorgova showed substantial variations in results. The sediment samples were characterized by a relatively large scale of variations for WC%, with few maximum values around 40% of the dry weight of the sample (Table 1). The magnitude and variability of the moisture content are interrelated with the quantity of the dry matter residuum quantity present in each sample. The physical features of the bed-sediment like the depth, texture and structure are responsible for the sediment moisture storage. The water content was inversely related to the dry matter content. The results showed that the organic substance (TOM%) was prevalent in the majority of samples, showing values greater than 50% of the dry weight of the sample (Table 1). Different exceptions occurred in sampling locations that are influenced by

Danube Delta Lakes as Sinks for Natural …

57

active hydrodynamic conditions, such as in the vicinity of a channel mouth, or, nearshore environments. The spatial intercomparison of the distribution maps (Fig. 12) did not show significant discrepancies within investigated sampling sites. The area of Rusca - Gorgova - Uzlina is positioned close to the DR supply through the secondary hydrographic network of waterways. Thereby, the abundant TOM% load occurred in the investigated samples contain presumably a mixture of organic matter materials from both exogenous (vegetation on the shores of lakes or transported by waterways) and endogenous sources (underwater vegetation, aquatic organisms). In accordance with the results obtained for organic substance (TOM%) (Table 1), the investigated sediments were grouped as organic sediments (≥15–30% organic compounds), and, subsidiary, as mineral sediments (≤15–30% organic compounds). The carbonate content (CAR%) values indicated a relative range of variations within the interpolated results (Table 1). A number of significant discrepancies were

Fig. 12 Interpolated spatial distribution maps showing the concentration of TOM% in bedsediments of investigated lakes: Uzlina (a), Pojarnia (b), Chiril (c), Isacova (d), Is˘accel (e), Durnoliatca (f) and Gorgova (g)

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I. Catianis et al.

encountered related to the sampling site location. There is a large amount of spatial variability amongst some investigated lakes, including also a spatial clustering of carbonate occurrences in other investigated lakes from this area (Fig. 13). The content of carbonates may be primarily linked to the disintegration of the skeletons of benthic organisms, algae, macrofauna shell formations, shell debris etc. In function of the results obtained from laboratory analyses (percentage of sediment carbonates) (Table 1), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, as low calcareous (10% < CaCO3 ≤ 30%). SIL% content fraction showed various results, included in a relatively narrow range of variations, with lower values no more than 30% (Table 1). Some samples collected from certain sectors of lakes revealed few maximal values (Fig. 14). These higher values were encountered in areas characterized by active, hydrodynamic (and

Fig. 13 Interpolated spatial distribution maps showing the concentration of CAR% in bedsediments of investigated lakes: Uzlina (a), Pojarnia (b), Chiril (c), Isacova (d), Is˘accel (e), Durnoliatca (f) and Gorgova (g)

Danube Delta Lakes as Sinks for Natural …

59

Fig. 14 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: Uzlina (a), Pojarnia (b), Chiril (c), Isacova (d), Is˘accel (e), Durnoliatca (f) and Gorgova (g)

mixing) environments. These environmental conditions can mobilize and recirculate the unconsolidated mineral particles existent in the superficial deposits of the underlying parent materials. E.

Fluvio-marine delta plain (eastern part) - Lumina - Ros, u Depression

The analyses carried out on samples taken from lakes as Iacub, Puiulet, , Lumina, V˘atafu, Puiu, Ros, u and Ros, ulet, are presented further on. The sediment samples were characterized by a relatively narrow variability of values for WC%, having values around 30% of the total weight of the dry residue (Table 1). The variations can be correlated with the structural and textural characteristics of the sediment material. TOM% fraction was prevalent in the majority of samples, with values more than 50% of the total weight of dry residue (Table 1), excepting some sampling sites located near to the entrance of various waterways. The highest levels of organic matter mainly occurred as a result of the in-lake hydrodynamic interaction of sediment and

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I. Catianis et al.

Fig. 15 Interpolated spatial distribution maps showing the concentration of TOM% in bedsediments of investigated lakes: Iacub (a), Puiulet, (b), Lumina (c), V˘atafu (d), Puiu (e), Ros, u (f) and Ros, ulet, (g)

water, generally, in areas characterized by low hydrodynamic conditions and calm depositional environment. The spatial distribution maps evidenced areas with high TOM% content (Fig. 15). In conformity with the results obtained for organic substance (TOM%) (Table 1), the investigated sediments were classified as organic sediments (≥15–30% organic compounds), and, subsidiary, as mineral sediments (≤15–30% organic compounds). Content of carbonate materials (CAR%) measured in the investigated samples showed variation in results (Table 1). The sampling sites with notably higher content (10% < CaCO3 ≤ 30% and 30% < CaCO3 ≤ 50%) were noticed in some sectors of Ros, u, Ros, ulet, and Puiu lakes (Fig. 16). Most likely, the carbonate occurrences are mainly related to biogenic materials derived from the skeletal materials, carbonate shells and shell debris. In function of the results obtained from laboratory analyses (percentage of sediment carbonates), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, as low calcareous (10% < CaCO3 ≤ 30%), and calcareous sediments (30% < CaCO3 ≤ 50%). The obtained results for SIL% variations are shown as contour maps with a relative variation at the local scale (Fig. 17). The occurrences of the silica-rich sediment samples are in connection with underlying parent materials (unconsolidated mineral materials that generally settle near the mouth of the secondary channels).

Danube Delta Lakes as Sinks for Natural …

61

Fig. 16 Interpolated spatial distribution maps showing the concentration of CAR% in bedsediments of investigated lakes: Iacub (a), Puiulet, (b), Lumina (c), V˘atafu (d), Puiu (e), Ros, u (f) and Ros, ulet, (g)

Fig. 17 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: Iacub (a), Puiulet, (b), Lumina (c), V˘atafu (d), Puiu (e), Ros, u (f) and Ros, ulet, (g)

62

F.

I. Catianis et al.

Delta front—Transitional area

The investigations performed on samples collected from Musura Bay and Sahalin Bay did not indicate a significant variability of the obtained values. The WC% showed slight variations within each sample, having values around maximum 33% of the total weight of the dry matter residuum. The results showed that the TOM% content has lower values, lower than 50% of the total weight of the dry matter residuum (Table 1). Lower values of TOM% contents were encountered in areas characterized by large unregulated freshwater flowing’s or strongly influenced by BS waves, tides and winds (intense hydrodynamic and mixing processes) (Fig. 18). Presumably, the organic matter content originates mostly from allochthonous inputs (terrestrial and aquatic plants etc.), supplied by Danube distributaries, and to a lesser extent may be attributed to autochthonous production. In conformity with the results obtained for organic substance (TOM%) (Table 1), the investigated sediments were grouped as organic sediments (≥15–30% organic compounds), and, subsidiary, as mineral sediments (≤15–30% organic compounds). Acquired results for carbonate rich-materials (CAR%) identified in the investigated samples, showed inconsequential variations with a range of variations which is relatively narrow (Table 1). Relatively higher CAR% contents are shown as spatial distribution maps (Fig. 19). The occurrence of the carbonate content included both freshwater and brackish water biogenic materials and biogenic debris derived from the skeletal materials, carbonate shells and shell debris. Based on the results obtained from laboratory analyses (percentage of sediment carbonates) (Table 1), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, as low calcareous (10% < CaCO3 ≤ 30%). The siliciclastic matter (SIL%) amount fluctuated in samples collected from Musura Bay, as well as in those collected from Sahalin Bay. It was noticed different

Fig. 18 Interpolated spatial distribution maps showing the concentration of TOM% in bedsediments of investigated lakes: Musura Bay (a) and Sahalin Bay (b)

Danube Delta Lakes as Sinks for Natural …

63

Fig. 19 Interpolated spatial distribution maps showing the concentration of CAR% in bedsediments of investigated lakes: Musura Bay (a) and Sahalin Bay (b)

Fig. 20 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: Musura Bay (a) and Sahalin Bay (b)

dominant levels of siliciclastic matter, with values greater than 45% of the dry weight of the sample (Table 1). Elevated levels of siliciclasts were generally noticed in the areas significantly influenced by the marine environment (Fig. 20). Generally, most of the siliciclastic fraction is stored inside their semi-enclosed basins. The interchange of sediment between these bays and the BS open waters is influenced by the amount of the discharged sediment material brought by the DR through Chilia, Sulina and Sf. Gheorghe distributaries, specific topography of the sea bottom and subaquatic currents. G.

Razim - Sinoie Lagoon Complex

The analyses carried out on samples taken from the lakes as Razim, Golovit, a, Zmeica, Sinoie, Babadag and Histria are presented below. The moisture content (%) showed slight variations within each sample, having values around maximum 40% of the total weight of the dry residue.

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Fig. 21 Interpolated spatial distribution maps showing the concentration of TOM% in bedsediments of investigated lakes: Razim (a), Golovit, a (b), Zmeica (c), Sinoie (d), Babadag (e) and Histria (f)

The obtained results from the analysis provide several interesting variations of the main lithological components (TOM%, CAR% and SIL%) in reference to the investigated transitional aquatic environments. It was noticed that the TOM% content measured in samples taken from the RazimSinoie lagoon complex, varied greatly on the local scale, with values around 40–50% (mean value) of the total weight of dry residue (Table 1). The spatial distribution map elaborated for the Razim-Sinoie lagoon complex, showed higher values of TOM% content spotted in Razim (N, S-E and S-V part), Golovit, a (more than the western half) and some spatial clustering of TOM% occurrences in Sinoie L. (eastern central and southern part) (Fig. 21). An explanation for the pattern of occurrence and spatial distribution of the TOM% content in these surficial sediments may be given as a consequence of the natural variations that take place in such environment, constantly vulnerable to hydrological and climatic factors of varying frequency and magnitude. The highest levels of TOM% content occurred in specific sectors of lakes, could be closely linked to areas characterized by low hydrodynamic conditions and plenty of endogenous organic material. Instead, lower levels of TOM% content were noticed in areas characterized by more dynamic conditions as DR freshwater water-level variations (by Dunav˘at, , Mustaca and Dranov Cnls.), infrequent saltwater inflows, strong winds and fast underwater currents. These frequent disturbances impact the water column turbidity that has a considerable effect on the remobilization of the lithogenic matter, impeding eventually, the deposition of organic matter material. Therefore, these lakes are included in the category of ecosystems with complex sedimentary environments. In conformity with the results obtained for organic substance (TOM%) (Table 1), the investigated sediments were classified as organic sediments (≥15–30% organic compounds), and, subsidiary, as mineral sediments (≤15–30% organic compounds). CAR% content measurements on samples collected from Razim-Sinoie lagoon complex showed variation in results (Table 1). The spatial distribution maps spotted small areas of lakes with both lower and higher values (Fig. 22). The amount of carbonate (CAR%) contents are related to both freshwater and brackish water large

Danube Delta Lakes as Sinks for Natural …

65

Fig. 22 Interpolated spatial distribution maps showing the concentration of CAR% in bedsediments of investigated lakes: Razim (a), Golovit, a (b), Zmeica (c), Sinoie (d), Babadag (e) and Histria (f)

bioaccumulations of carbonate materials and biogenic debris. They consist mostly of fine, coarse and very coarse calcareous shell debris admixed in sediment matrix. Authigenic carbonates may also occur as a result of the calcareous rocks within the depositional area, particularly in the western shores of the Razim lagoon, particularly, near Cape Dolos, man (a limestone cliff), or, as a consequence of the mechanical abrasion of endogenous and exogenous carbonate segments existent in the area. As concerns the results obtained from laboratory analyses (percentage of sediment carbonates), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, as low calcareous (10% < CaCO3 ≤ 30%) and calcareous sediments (30% < CaCO3 ≤ 50%). Relatively high levels of SIL% content with values around 50% of the dry weight of the sample (Table 1) were noticed. In general, the distribution maps (Fig. 23) revealed that the elevated levels of the siliciclastic matter could be owed to the terrigenous material supplied by the interdistributary channels or due to natural processes of the banks erosion. Moreover, the proximity of these lakes to the BS mixed sediment environment induces their susceptibility to local climate changes. Strong winds and high waves tend to transport sediment back and forth, producing shoreline erosion.

Fig. 23 Interpolated spatial distribution maps showing the concentration of SIL% in bed-sediments of investigated lakes: Razim (a), Golovit, a (b), Zmeica (c), Sinoie (d), Babadag (e) and Histria (f)

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In this sense, the occurrences of the silica-rich sediment samples might be linked to both endogenous lithogenic materials (underlying parent substrate), as well as exogenous, terrestrial and marine sediment sources. The analyses performed on samples collected from Babadag L., showed significant variations for TOM% content, with values around 50% of the total weight of dry residue (Table 1). The maximum values of organic content (TOM%) (Fig. 21) occurred in areas characterized by low hydrodynamic conditions, in shallow water environment slightly disturbed by bottom water currents which allow the abundance of endogenous organic matter accumulation. Instead, around the shores of the lake occurred lower levels of TOM%, probably as a result of more active hydrodynamic conditions. In accordance with the results obtained for organic substance (TOM%) (Table 1), the investigated sediments were grouped as organic sediments (≥15– 30% organic compounds), and, subsidiary, as mineral sediments (≤15–30% organic compounds). The CAR% values indicated a relative range of variations within the interpolated results (Table 1). The occurrence of carbonate peaks in Babadag L. (Fig. 22) could be related to large bioaccumulations of shells. In function of the results obtained from laboratory analyses (percentage of sediment carbonates), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, as low calcareous (10% < CaCO3 ≤ 30%) and calcareous sediments (30% < CaCO3 ≤ 50%). The investigated samples for SIL% content indicated variation in results (Table 1). The spatial distribution map (Fig. 23) showed that the higher values occurred around the shores of the lake. The analyses carried out on samples taken from Histria L., indicated results with values greater than 50% of the dry weight of the sample (Table 1). The organic substance (TOM%) was dominant in the vast majority of samples, apart from some sampling sites placed near to the entrance of water supply channels (W and E part of the lake) (Fig. 21). In conformity with the results obtained for organic substance (TOM%) (Table 1), the investigated sediments were classified as organic sediments (≥15–30% organic compounds), and, subsidiary, as mineral sediments (≤15–30% organic compounds). CAR% content measurements in samples collected from Histria L., showed variation in results (Table 1). The occurrence of carbonate peaks in Histria L. (Fig. 22) could be related to large bioaccumulations of shells. According to the particular results obtained from laboratory analyses (percentage of sediment carbonates), the investigated sediments were grouped as non-carbonated sediments (CaCO3 ≤ 10%), and subsidiary, low calcareous (10% < CaCO3 ≤ 30%) and calcareous sediments (30% < CaCO3 ≤ 50%). SIL% content fraction showed various results, included in a relatively large range of variations (Table 1). Higher values of siliciclastic components (SIL%) were noticed in the eastern segment of the lake (Fig. 23). The results described above are in accordance with preceding studies and researches linked to sedimentological investigations on recent sedimentary deposits from the vast area of the DD [64, 125–136].

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5 Conclusions In this study, bed-sediments of 36 lakes (larger or smaller) from the lagoon-deltaic edifice of the DD were studied in detail. The distribution of the presented proxies revealed typical spatial variability in the function of the sampling site’s geographical position, reflecting different depositional environments and limitative factors. The spatial variability of the organic matter, carbonates and siliciclasts in the lakes, evidences that the sediments in different areas have different vulnerabilities to local environmental changes. The obtained results indicated that the occurrence of the total organic matter, total carbonates and siliciclasts in bed-sediments of the investigated lagoon-deltaic ecosystems is in relation to both endogenous and exogenous inputs. Consequently, the lagoon-deltaic sediments will incorporate a mixture of sediments enriched more or less with organic matter, carbonates and siliciclasts that come from regional and local, and from recent to past, sources. Most of the siliciclasts are brought by the Danube River, through channels and canals, but only deposit in the vicinity of the inflow area. The large amount of the total organic matter and total carbonates (autochthonous) show that this represents an important contribution of the total sedimentation, which, to date, are poorly quantified in the DD. Generally, the recent accumulations of sedimentary deposits, sediment texture and lithological composition were used to identify individual sedimentary profiles that can be generally transposed in terms of depositional environments. Spatial distribution of sedimentary profiles may specify progressive trends that can be correlated to changes of the DR water and sediment inputs. Coarse sediments deposited in the brackish-water conditions, in the transition zone, accompanied by the high turbidity currents and dynamic conditions were also identified. The association of sedimentary profiles identified within this study is summarized below, and the following broad depositional environments are recognized: Fluviatile (continental): Dynamic/passive channels, meandering channels, braided channels - dominantly sand with little content of silt or clay, and subordinately allochthonous plant debris; Deltaic/lacustrine (transitional): muds rich in fine and coarse organic matter admixed with small amounts of sand and clay, commonly with autochthonous plant debris, including a significant fraction of authigenic biogenic carbonates (shells, fragments of shells and shell debris); Delta front (transitional zone, near the mouth of the DR distributaries and proximal shore face). River influenced and marine dominated shore face deposits are characterized by accumulations of sand of fine to coarse grain size, with slight amounts of silt and clay and variable content of plant debris and shell debris; Coastal environment (transitional): fine to medium sand, with typically silty clay and clayey silt accumulations specific to lagoonal settings, commonly silty because of mixing environment, with abundant shell fragments and debris, articulated shells, and significant content of plant debris.

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Having a general view of the provenance (allochthonous or autochthonous), composition and grain size of lake sediments will improve any further knowledge on both quality and quantity of water and sediments and as well as the ecosystem.

6 Recommendations A better knowledge of the organic component of sedimentation in deltas is required at a global level. This is even more important where deltas are affected by coastal erosion and sediment loss, as it is the case of the DD [137]. An increase in the organic sedimentation may show a strong eutrophication phenomenon and hypoxia, in the DD lakes, which is already known, but which impacts both water and sediment quality. Some studies have already pointed out that water circulation has been decreasing in several areas of the delta [138]. This phenomenon, coupled with the effects of climate change, such as increasing spring temperature of water bodies [139], alters the quality of aquatic habitats, and the life cycle of all biota. This is important for a better management of natural resources, particularly for fish stocks, which is one of the most important natural resources in many deltas. A closer look at the effects of the altered water circulation of the delta has on the lake habitats, for the quality of both sediment, water and biota is recommended. Water and sediment circulation can be enhanced by dredging of channels and canals and reopening areas clogged by reed beds. More studies on lake sediments would also provide a better picture on water and sediment quality and on the capacity of the sinks to retain pollutants such as heavy metals [140] and macro or micro plastics [141]. Acknowledgements The research leading to these results was supported by the Ministry of Education and Scientific Research—“The Core Programme: PN 09 41 03 04, PN 16 45 01 04, PN 18 16 01 02 and PN 19 20 02 03”.

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Assessment of Climate Conditions and Changes Detected Over the Historical Period (1961–2013) Adina-Eliza Croitoru, Csaba Horvath, and Titus-Cristian Man

1 Introduction Under the present climate changes, indices for climate variability and extreme events have been used to understand how extremes are changing either globally or in specific regions [1]. They have been employed for a few decades, often by assessing days with temperature or precipitation observations above or below specific physically-based thresholds. Some of these indices provide insight into local conditions, whereas a few physically based thresholds have relevance for different regions on the planet. Therefore, the number and types of the mean and extreme temperature and precipitation indices consistently developed over the last two decades and now often focus on relative thresholds that describe features in the tails of the distributions of meteorological variables. At international level, a subset of the wide range of possible indices has been developed under the coordination of the Expert Team for Climate Change Detection, Monitoring and Indices (ETCCDMI) and Expert Team for Specific Sector Indices (ET-SSI) in order to help understanding the changes at a wide range of spatial A.-E. Croitoru · C. Horvath (B) Department of Physical and Technical Geography, Faculty of Geography, Babe¸s-Bolyai University, 5-7, Clinicilor, 400006 Cluj-Napoca, Romania e-mail: [email protected] A.-E. Croitoru e-mail: [email protected] Research Centre for Sustainable Development, Faculty of Geography, Babe¸s-Bolyai University, 5-7, Clinicilor, 400006 Cluj-Napoca, Romania T.-C. Man Department of Regional Geography and Territorial Planning, Faculty of Geography, Babe¸s-Bolyai University, 5-7, Clinicilor, 400006 Cluj-Napoca, Romania e-mail: [email protected] Centre for Regional Geography, Faculty of Geography, Babe¸s-Bolyai University, 5-7, Clinicilor, 400006 Cluj-Napoca, Romania © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_3

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scales from local to global. They allow the results of studies from different regions of the world to fit together seamlessly and be compared [2]. This topic has become one of the most popular in climate literature worldwide over the last few decades. Consistent efforts have been made to identify changes in the main features of the extreme temperature and precipitation events: frequency, intensity, and duration [3–14]. At the end of the twentieth century, research conducted at global scale reported the daily minimum temperature with a more intense increase compared to the daily maximum temperature [15]. From the beginning of the twentyfirst century many researchers worldwide found a significant increase in duration, frequency, and intensity of the maximum temperature derived indices and a significant decrease for the minimum temperature data sets [16]. At the same time, spatially inconsistent trends have been found for extreme precipitation indices. Studies have been conducted at three spatial levels. First, research papers covered a global [10] and broader spatial scale such as Europe, China, South America, Asia-Indo-Pacific region prevailed [5, 9, 16–23]. But, the frequency and severity of extreme weather events have increased globally, and it is expected to continue in the coming decades. Thus, understanding their characteristics is crucial due to their significant negative impacts on social, physical, and economic environments [24]. Furthermore, studies began to focus on a national, regional, or local scale [1, 8, 13, 21, 22, 26–40]. The indices analyses conducted by researchers from different regions and continents indicated a well-documented change in extremes, especially in temperature extremes [1, 2, 41]. One of the major conclusions is that global or continental scale studies on mean and extreme temperature indices revealed that the changes were as expected in a warming world: warm temperature extremes increased, whereas cold temperature extremes showed a downward trend [10, 36, 42, 43]. Detailed analysis indicated that mean and extreme precipitation indices have a spatial inconsistency in trend type for many regions of the planet. Most of them have shown a tendency toward wetter conditions throughout the twentieth century and the beginning of the twenty-first century, yet not statistically significant in some cases [10, 24, 44–51]. The Danube Delta, the most extensive wetland in the European Union and a global biodiversity hotspot [52], was subject to many studies on climate conditions. Thus, some information about climate change can be found in research papers developed for more extended regions. Most of them considered only point observation data registered at the weather stations [16, 46, 53–56]. Recently, a few papers considered for their analysis gridded data, but they focused on a small number of indices [57–59]. Some others identified evidences of recent storminess change and links with large-scale teleconnection patterns in the Danube Delta [60], or revealed significant changes in potential evapotranspiration, leading to an increased aridity climate [61–63]. Over the last decades, there were papers developed to investigate the impact of climate change to a large variety of environmental components such as hydrological cycles [64], impact of teleconnections on coastal dynamics of the Black Sea [65], or biodiversity [66]. From a theoretical perspective, the climate change impact on the Danube Delta was briefly considered in [67]. The threats were identified, and some proposals were made on coping with detected changes.

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The main aim of this research is to investigate if there is any specific regional pattern and changes in 25 mean and extreme temperature and precipitation indices in the Danube Delta over a historical period (1961–2013) calculated based on gridded data at a spatial resolution of 0.1 × 0.1° (latitude x longitude). This is the first study developed at such a detailed spatial resolution for extreme temperature and precipitation events in the focus region.

2 Data and Methods 2.1 Data Used To develop this study, we used daily gridded precipitation and extreme temperature (maximum - TX and minimum - TN) data to calculate 25 indices to characterize in details the main climatic parameters in the Danube Delta over a 53-yr historical period (1961–2013). No missing data were identified in the datasets. The data have a spatial resolution of 0.1° latitude/longitude (~11 × 11 km). They were extracted from the national climatic database, ROCADA, developed and made available by the Romanian National Meteorological Administration [68]. The entire region considered is covered by 63 grids (Fig. 1). Data derived from the same database, especially for temperature and precipitation, were successfully employed previously for different climatic or climate impact analysis for the entire Romanian territory or different regions [58, 59, 69–76]. The ROCADA original datasets are freely available online on PANGAEA (https://doi.pangaea.de/10.1594/PANGAEA.833627) [68].

2.2 Methods This sub-section focused on three issues: methods used for calculating the mean and extreme temperature and precipitation indices, their trend detection method, and the mapping techniques.

2.2.1

Indices Calculation

The scientific community in climatology emphasizes using various indices to better assess the impact of mean and extreme temperature and precipitation on different sectors. However, the common opinion is that the more indices are used, the better and more reliable image of the changes in the extreme temperature and precipitation is presented in a specified area [46]. In this chapter, 25 indices on temperature and precipitation were analyzed: 20 indices for temperature and five indices for precipitation. We detailed their definitions

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Fig. 1 Study region and grid network

and units in Table 1. The indices were extracted from the lists proposed by the Expert Teams for Climate Change Detection Indices (ETCCDI) and Sector-Specific Climate Indices (ET-SCI). The standardization of these indices allows researchers to compare results across different periods, regions, and source datasets [77]. This chapter focused on analyzing mainly extreme high and low temperature indices and extreme high precipitation indices. The high number of temperature indices was selected because most previous papers developed for Romania or the Black Sea western region indicated more important temperature changes than precipitation. We considered the low precipitation indices irrelevant for this analysis since the Danube Delta is a wet region dominated by water surfaces and thus not much affected by low precipitation events. On the contrary, extreme high precipitation is critical in the focus area because it is prone to flash and/or high floods.

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Table 1 Temperature and precipitation indices definitions and units (after www.climpact-sci.org, modified) Index acronym

Index long name

Definition

Unit

Temperature non-threshold indices TMm

Mean TM

The mean daily mean temperature

°C

TXx

Maximum value of TX

The maximum value of TX in a year

°C

TXm

Mean TX

The mean daily maximum temperature

°C

TNm

Mean TN

The mean daily minimum temperature

°C

TNn

Minimum value of TN

The minimum value of TN in a year

°C

Temperature indices calculated based on fixed thresholds FD

Number of frost days

The annual number of days when TN < 0 °C

Days

ID

Number of ice days

The annual number of days when TX < 0 °C

Days

TR

Number of tropical nights

The annual number of days when TN > 20 °C

Days

TXge30

TX of at least 30 °C (tropical days)

The annual number of days when TX ≥ 30 °C

Days

TXge35

TX of at least 35 °C (hot days)

The annual number of days when TX ≥ 35 °C

Days

Temperature indices calculated based on location thresholds HWN

Heatwave number as defined by the Excess Heat Factor (EHF)

The number of individual heatwaves that occur each extended summer (May–Sep) season A heatwave is defined as 3 or more days where the EHF is positive, where percentiles are calculated for 1961–1990

Events

HWD

Heatwave duration

The length of the longest heatwave, identified by HWN

Days

HWF

Heatwave frequency

The number of days that contribute to heatwaves, as defined by HWN

Days

HWA

Heatwave amplitude

The peak daily value in the hottest heatwave (defined as the heatwave with the highest HWM)

°C2

(continued)

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Table 1 (continued) Index acronym

Index long name

Definition

Unit

HWM

Heatwave magnitude

The mean temperature of all heatwaves identified by HWN_EHF

°C2

CWN

Coldwave number as defined by the Extreme Cold Factor (ECF)

The number of individuals coldwaves that occur each year during extended winter (Nov-Apr.) season, identified based on ECF

Events

CWD

Coldwave duration

The length of the longest coldwave identified by CWN

Days

CWF

Coldwave frequency

The number of days that contribute to coldwaves, as defined by CWN

Days

CWA

Coldwave amplitude

The minimum daily value in the °C2 coldest coldwave (defined as the coldwave with the lowest CWM)

CWM

Coldwave magnitude

The mean temperature of all coldwaves identified by CWN

°C2

Precipitation indices calculated based on fixed thresholds R10mm

Number of heavy rain days

Annual number of days when daily precipitation amount ≥ 10 mm

Days

R20mm

Number of very heavy rain days

Annual number of days when daily precipitation amount ≥ 20 mm

Days

Precipitation non-threshold indices PRCPTOT

Annual total wet-day PR

Annual total precipitation on wet days (wet day = day when the precipitation amount ≥ 1.0 mm

mm/yr

Rx1day

Max 1-day PR

Annual maximum 1-day precipitation

mm

Rx3day

Max 3-day PR

Annual maximum precipitation accumulated in 3 consecutive days

mm

The indices can be classified into different categories regarding definition and calculation [1]. Thus, based on their computation algorithm, temperature and precipitation indices are classified into three classes [13, 16, 26, 46, 56, 78, 79]. a.

Non-threshold indices class covers the indices computed considering the absolute values of temperature and precipitation recorded in a specific area. No minimum or maximum threshold was considered for their identification. In

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b.

c.

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general, they are considered intensity indices, and they are very sensitive to the general climate of the focus region. Usually, they do not allow comparison among areas with different climate types (even the altitude can impose significant differences in small regions) [16, 46]. However, this type of indices is appropriate for a comprehensive climatic analysis because the focus region is homogenous and small. Five such indices for temperature (TMm, TXx, TXm, TNn, and TNm) and three for precipitation (Rx1day, Rx3days, and PRECPTOT) were considered for this study. Indices based on location-related thresholds are calculated using an averageor percentile-based threshold. In this paper, we used location-related thresholds only for temperature. Generally, they are defined as days surpassing or staying below the long-term metric (percentile or mean multi-annual value). This is a commonly used method to determine the extreme values in climatology [10, 80]. Additionally, they can be used for a wide variety of climates because their definitions are objective, site independent and facilitate direct comparisons between different regions [16, 18, 46, 81]. In this paper, indices characterizing heatwaves (HWs) and coldwaves (CWs) (Table 1) are specific for this class (HWN, HWD, HWF, HWM, HWA, CWN, CWD, CWF, CWM, and CWA). They were derived based on Excess Heat Factor (EHF) and Excess cold factor (ECF) using a procedure described in [82] and [83]. Indices calculated based on fixed thresholds are defined using a certain fixed threshold of temperature/precipitation. They are location-sensitive and thus greatly vary from one region to another. They are essential, especially for detailed spatial scales, as is the case for the Danube Delta [16, 26, 46]. This chapter analyzed five such indices for temperature (FD, ID, TR, TXge30, and TXge35) and two for precipitation (R10 and R20).

We consider that the chosen indices provide a good mixture of intensity and frequency indices both for temperature and precipitation. We calculated the indices by using ClimPACT2 software (https://climpact-sci.org/), R version. Further, the resulting series were analyzed for each index through the spatial distribution of their mean and extreme annual values and trends.

2.2.2

Trend Detection

The trends for indices evolution over the historical period were calculated automatically by ClimPACT for each index [84]. The procedure is based on Sen’s slope and employs the .zyp package in R (https://cran.r-project.org/web/packages/zyp/zyp. pdf). The applied method reflects the median slope of all ordered pairs of points in a dataset. It is more appropriate for calculating trends in extreme values - compared to other common trend estimators like the least-squares method - since outliers less impact it [85]. A combination of Mann–Kendall test for trend [86, 87] with Sen’s non-parametric method for the magnitude of the trend [88] is a very common procedure for the

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analysis of climatic variables and parameters, including temperature and precipitation indices [89–94]. For this study, the statistical significance threshold (α level) is 0.05. To calculate the share of the area affected by trend types (given in %), we considered only those grids inside the region’s limit. The number of pixels (grids) with a specific trend type (statistically significant increase or decrease, non-statistically significant increase or decrease, and no change/stationary) was divided by the total number of pixels covering the entire study area (63) and then multiplied by 100.

2.2.3

Base Map and Mapping Procedure

The indices were spatialized using the inverse distance weighted (IDW) interpolation method by employing the ArcGIS PRO v 2.8 software [95]. Due to the data characteristics, with data points distributed in a regular grid-shaped point dataset covering the entire area, the IDW interpolation was chosen as the most appropriate for this type of spatial distribution. The interpolation allowed to predict values at unsampled locations, creating maps for the selected indices as well as maps for trend type and their statistical significance. For spatial distribution maps, the grid points inside the region limit were considered as well as the next points outside the limit. This method is appropriate for this type of analysis because the considered data is systematically organized at the exact distances from the center of the grid’s pixels. IDW presumes that each measured point has a local influence that diminishes with distance [95]. As interpolation was not needed for trend-type spatial representation, we considered only those points inside the Danube Delta region limit. The input data for the analysis was projected in Stereo 1970 (Romania’s National Projection System) to make our results compatible with other national GIS databases.

3 Results and Discussions 3.1 Temperature Analysis 3.1.1

Spatial Distribution and Trends of Non-Threshold Indices

The mean multiannual temperature for the analyzed period exceeded 11.5 °C for the largest area of the Danube Delta. Only the extreme western region was characterized by temperatures of 10.5–11.5 °C (Fig. 2a). For the extreme temperatures recorded, both mean and historical extremes indicated the increase of continentalism westward, with maximum (for TXm and TXx) and, respectively, minimum (for TNm and TNn) values in the west of the region (Fig. 2b-e). Compared with spatial variation of the mean multiannual values, the differences between the eastern and the western parts of the region increased to more

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Fig. 2 Spatial distribution of mean multiannual and historical extreme temperature values in the Danube Delta over the period 1961–2013

than 2 °C in case of the mean values of extreme temperatures (TXm and TNm) and more than 5 °C for the historical values recorded (TXx and TNn). The differences are slightly higher for TN: the mean multi-annual value of daily TX increases from less than 14.5 °C to more than 16.5 °C (Fig. 2b) and those of daily TN from 6.0 °C to 8.1…8.5° (Fig. 2d). The extreme historical temperatures registered varied between -25.9 and 40.4 °C in the western continental area of the Danube Delta and between -18.8 and 34.9 °C on the Black Sea coastline (Fig. 2 c,e). In terms of change detected, for all indices considered in this section (except for TNn), the Danube Delta experienced a statistically significant increase over the analyzed period. A very small area indicated for TNm not statistically increase. For the TNn index, an insignificant increase characterized the entire region (Figs. 3 and 4, Table 2).

3.1.2

Spatial Distribution and Trends of Indices Calculated Based on Station-Related Threshold

We calculated ten HWs and CWs indices in this category. Five metrics were considered for each type of event: number of events in a year, duration of one event, cumulated duration of all events in a year (frequency), magnitude, and amplitude. Complete definitions are presented in Table 1.

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Fig. 3 The area covered by trend types of temperature and precipitation indices in the Danube Delta (%)

Fig. 4 Spatial distribution of trend type for non-threshold temperature indices

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Table 2 Frequency of trend types for the temperature and precipitation indices in the Danube Delta over the period 1961–2013 (% of the total grid number) Index

Significant increase

TMM

100.00

0.00

0.00

0.00

0.00

TXm

100.00

0.00

0.00

0.00

0.00

TXx

100.00

0.00

0.00

0.00

0.00

TNm

98.41

1.59

0.00

0.00

0.00

TNn

Not significant increase

No change

Not significant decrease

Significant decrease

0.00

100.00

0.00

0.00

0.00

HWN

100.00

0.00

0.00

0.00

0.00

HWD

98.41

1.59

0.00

0.00

0.00

HWF

100.00

0.00

0.00

0.00

0.00

HWM

1.59

95.24

3.17

0.00

0.00

HWA

100.00

0.00

0.00

0.00

0.00

CWM

0.00

98.41

0.00

1.59

0.00

CWD

0.00

11.11

0.00

88.89

0.00

CWF

0.00

77.78

0.00

22.22

0.00

CWM

0.00

71.43

1.59

26.98

0.00

CWA

0.00

0.00

0.00

100.00

0.00

FD

0.00

0.00

0.00

100.00

0.00

ID

0.00

0.00

0.00

100.00

0.00

TXge30

0.00

100.00

0.00

0.00

0.00

TXge35

65.08

30.16

4.76

0.00

0.00

TR

0.00

100.00

0.00

0.00

0.00

PRCPTOT

0.00

1.59

0.00

39.68

58.73

Rx1day

0.00

7.94

0.00

92.06

0.00

Rx3day

0.00

6.35

1.59

92.06

0.00

R10

0.00

3.17

0.00

39.68

57.14

R20

0.00

4.76

0.00

50.79

44.44

a.

HWs analysis For most HW indices, the values increased from the coastline towards the inland region. The only exception is the HWD, which indicated the most prolonged events in the eastern part of the Danube Delta and the shortest in the western area. However, the differences are not high due to the small extension and homogeneity of the focus area. Thus, the total number of events varies between 2.4 and 3.2 events/yr., one HW event lasts 7–8 days (HWD), and they cumulate in a year 14–18 days (HWF). The largest area recorded a magnitude of 3–4°C2 and an amplitude of 50–65°C2 (Fig. 5).

Regarding the trend types, HWN, HWF, and HWA indicated a statistically significant increase for the entire Danube Delta; for HWD, 98.41% of the area was characterized

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Fig. 5 Spatial distribution of HW indices over the period 1961–2013

by a significant increase, whereas HWM analysis revealed the same area covered by not significant increase (Figs. 6 and 3, Table 2).

Fig. 6 Spatial distribution of trend types for the HW indices over the period 1961–2013

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Fig. 7 Spatial distribution of CW indices over the period 1961–2013

b.

CWs analysis

Spatial distribution of the CW indices showed gradually higher values from the coastline towards the inland area, but as in the case of HWs, differences are not very large. Thus, the mean annual CWN ranges from 2.3 to 2.6 events/yr., the individual events last, as average, 8–9 days (HWD) and totalize in a year 14–16 days (HWF). Their magnitude varied in the range of -15 …-19°C2 , and the amplitude dropped to -151…181°C2 . The CWA is the only indicator showing a different spatial pattern (Fig. 7). Change analysis indicated that trends detected are not statistically significant and not in the same line for all indices: for CWN, CWF, and CWM, an insignificant increase is dominant, whereas, for the CWD and CWA, no significant decrease prevailed. However, except for CWA, which indicated a general not significant decrease over the entire region, the other indices were characterized by a mixture of not significant upward and downward trends (Figs. 3 and 8, Table 2). Under these conditions, we can conclude that CWs did not change much in the general context of global warming. However, they seem to have become shorter but more numerous and lower intensity.

3.1.3

Spatial Distribution and Trends of Indices Calculated Based on Fixed Thresholds

In this category, we considered five indices: three calculated based on TN (FD, ID, and TR) and two calculated by using TX (TXge30 and TXge35). All these indices are

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Fig. 8 Spatial distribution of trend types for the CW indices over the period 1961–2013

frequency indices, their value giving the number of days in a year below or exceeding the specified temperature threshold. Another classification, developed based on the data employed to calculate an index, would divide the above indices into “cold extremes” (FD and ID) and “hot extremes” (TR, TXge30, and TXge35). Compared with the previous categories of indices, the spatial differences are higher. The impact of the water bodies is visible, as the number of days with extreme temperatures considerably increases westward with the distance from the Black Sea, except for TR. Thus, FD largely varied from 65 days/yr. for the most extensive wet area of the Danube Delta to 95 days/yr., in the extreme west of the region (Fig. 9a). In general, 13–19 days/yr. can be classified as ice days, but their number dramatically increases westward up to 32 days/yr., along the Danube River (Fig. 9b). The “hot extremes” indicated the same spatial pattern in case of tropical days (TXge30) and hot days (TXge35). The eastern third of the Danube Delta was characterized by less than 10 days/yr. In the extreme west of the region, the frequency rose up to more than 35 days/yr. (Fig. 9c). Due to large water surfaces, hot days are quite rare in the focus area: usually, less than 3 days/yr., as average value. The threshold for such days is not exceeded each year for the largest area inside the Danube Delta, which is characterized by less than 0.5 days/yr. (Fig. 9d). TR frequency spatially varies in the range 4–21 days/yr., which is much higher in the coastal region than the nearby land area (Fig. 9e); the sharp increase eastward is most likely due to the thermal moderating effect of the vicinity of the Black Sea. In terms of changes detected, except for TXge35, which indicated a significant increase in the western half of the focus region, the others showed no significant

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Fig. 9 Spatial distribution of fixed-threshold indices over the period 1961–2013

changes. The “cold extremes” (FD and ID) decreased, whereas the hot extremes (TR, TXge30, and TXge35 for the eastern half of the delta) increased (Figs. 3 and 10, Table 2). However, the opposite trends for the indices in this category are in line with global warming, denoting fewer days with “cold extremes” and more days with “hot extremes” [10, 36, 42, 43].

3.2 Precipitation Analysis The Danube Delta is one of the driest regions of Europe, especially in its eastern half, where annual precipitation is quite close to the aridity limit (250 mm) [55]. For precipitation, we analyzed five indices: three are no threshold indices (PRCPTOT, Rx1day, and Rx3days) and two are fixed-threshold indices (R10 and R20). They are a mixture of frequency and intensity indices. The spatial pattern is similar for all indices, indicating an increase in precipitation amount or frequency from east to west. They registered considerably higher values in the western part of the region than the coastal line (Fig. 11). The annual precipitation cumulated in wet days (days exceeding 1 mm) ranges from 258 to 448 mm. When the maximum 1-day and 3-day amount was analyzed, about 10% of the annual amount could fall in one day or three consecutive days, indicating a torrential regime of precipitation with a high amount concentrated in a low number of days. This conclusion is also supported by the frequency indicators (R10 and R20), with their average values of 6–13 days/yr. and 1–3.5 days/yr. (Fig. 11).

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Fig. 10 Spatial distribution of trend types for the temperature fixed-threshold indices over the period 1961–2013

Fig. 11 Spatial distribution of extreme precipitation indices over the period 1961–2013

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Fig. 12 Spatial distribution of trend types for the extreme precipitation indices over the period 1961–2013

Trends detected revealed a general decrease in precipitation over the Danube Delta. A significant reduction was dominant (57–58%) for two indices (PRCPTOT and R10). A consistent share of significant decrease covered the Danube Delta for the R20 indicator, too (Figs. 3 and 12, Table 2). These results are somehow different from the rest of Romania or the Black Sea area, where most precipitation indicators were found to have no significant decreasing trends [16, 95]. Small areas (less than 8%) experienced not significant increase for all indices. They are located especially near the western border of the region (Figs. 3 and 12, Table 2).

4 Discussions and Conclusions This study revealed a similar spatial pattern both for temperature and precipitation indices, greatly influenced by the vicinity of the Black Sea. Moreover, large areas covered by water bodies induced a slight spatial variation in most indices’ values. The hot extremes indicated significant primarily increasing trends, whereas a dominant decrease was found for cold extremes and precipitation indices. This result is in agreement with studies developed in other regions of the world, which reported that over 70% of the global land area showed a significant decrease (increase) in the annual occurrence of cold (warm) nights [10, 36].

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Since climate change effects have impact on a large variety of domains and regions, the Danube Delta Biosphere Reserve ecosystem area is not an exception [66]. The combined results revealing a dominant significant increase for extremely high-temperature indices and decreasing precipitation suggest that the climate has become warmer and drier over the last five decades in the Danube Delta. This fact could be crucial for the complex and unique ecosystem of the Danube Delta: its labyrinth of channels, lakes, marshes, and dunes, about 2,000 plant and 5,000 animal species, could be under a severe threat [52]. Climatic factors considerably influence the spreading of invasive plant species. Habitat alteration (decreasing, increasing, or shifting species’ range in size and abundance) was largely impacted by the changes occurred in the climatic features of the focus region [66, 97]. In the climate change context, one of the effects is the spread and persistence of invasive plant species in natural habitats and the interference on plant community’s structure [66]. Species that tolerate a wide range of climatic conditions could become the most successful invaders [66, 98]. Large precipitation variations could cause waterdemanding/resistant species to outcompete one another [66]. From the perspective of alien’s bio-geographical origin, significant increasing temperatures seems to favor some species of Mediterranean origin to spread northwards and enhance the winter survival chances of some other organisms [66, 99]. Under these circumstances, this study could become an important tool for environmental scientists and other stakeholders to make the most appropriate decisions to efficiently protect the unique and complex ecosystem of the Danube Delta.

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Water Flow Variability in the Danube Delta Under Climatic Changes Conditions Maria Cristina Trifu, Constantin Borcia, Ecaterina Luca, and Roxana Bojariu

1 Introduction The Danube Delta, together with the deltas of other rivers, is considered a fragile ecosystem, vulnerable to natural and anthropogenic pressures. Natural factors with the greatest impact include global climate change, which is also leading to changes in the hydrological regime of the Danube. Regarding the water runoff on the Danube, it should be noted that there are two extreme flow regimes: high water regime (or maximum runoff), which occurs especially in the spring–summer due to the overlapping effects of melting snow and falling rainfall throughout the basin and the low water regime (or minimum runoff), which occurs during a year in three periods: in early spring, autumn and winter, when the lowest flow values are recorded. The hydrotechnical works, accomplished over the time, both on the Danube and the Delta’s branches, have influenced the hydrological regime of the water and sediments. Relative stages of the evolution of Danube hydrological regime evolution can be made, as follows: • period of the natural regime (until 1857), when started the first riverbed modifications for maritime navigation purpose, carried out by the former European Commission of the Danube [1];

M. C. Trifu (B) · C. Borcia · E. Luca Department of Hydrology and Hydrometry of the Danube River and Black Sea, National Institute of Hydrology and Water Management, Sos. Bucuresti-Ploiesti, 97E, District 1, 013686 Bucharest, Romania e-mail: [email protected] R. Bojariu Department of Climate, National Administration of Meteorology, Sos. Bucuresti-Ploiesti, 97, District 1, 013686 Bucharest, Romania © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_4

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Fig. 1 Construction of two dikes made of stone blocks at Sulina mouth (continuation of Sulina canal in the Black Sea)

• period of the semi-natural regime (1857–1964), when important hydrotechnical works were carried, in order to modify the hydrological regime inside the Danube Delta: – 1857–1861—hydrotechnical arrangement of the mouth of the Sulina channel, by building two convergent dikes (Fig. 1); – 1868–1902—regularization of the Sulina channel (modification of the branch’s width, shortening the riverbed by about 21 km, impoundment of the banks); – 1872–1882—arrangement of the bifurcation of the Chilia-Tulcea arms and Sulina–Sfântu Gheorghe branches in order to modify the distribution of water flows on the channels and to increase the navigation depth on Tulcea branch and Sulina branch respectively (Fig. 2); – 1943—closing the mouth of the Stambulul Vechi branch, in order to reduce both the southward development of the Chilia Secondary Delta and the influence of sediment deposits on the output of the Sulina channel; • period of the transitional regime (1964–1984), in which the construction of the Iron Gate I and Iron Gate II reservoirs were accomplished and the impoundment of the Danube River floodplain was finalized; • period of the current regime (after 1985), characterized by the rectification works of the Sfântu Gheorghe branch (shortening the riverbed with about 31 km).

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Fig. 2 Hydrotechnical works made of stone blocks at the Chilia and Tulcea branchs bifurcation

The regularization of the Sulina channel and its mouth led to a considerable increase of the depth of navigation along the canal (from 2.75 m in 1856 to 7.32 m in 1894), having an important effect on the modification of the hydrological regime of Sulina canal, both by increasing over time the water flow and sediments, and by the natural deepening of its riverbed, along the entire route, from confluence with the Tulcea channel to its flow into the Back Sea. Following the works, the water flow of the Sulina channel increased from 7 to 9% of the total water flow of the Danube to 16–17% in 1921 and respectively 18–20% in present [2]. The development of the Chilia secondary delta had an impact on the conditions for maintaining maritime navigation through the mouth of the Sulina canal, which required measurements enforcement in order to limit the expansion towards the south of the Chilia secondary delta. These measures aimed at the extension of the dams in the sea (in 1927) and damming the southern branch of the Stambulul Vechi (Old Istanbul) canal (in 1942) [3]. An example of anthropogenic impact that led to debates and research based on integrated monitoring (hydrology/biology/chemistry), controversial even today, is the construction of the Bîstroe Canal (2004–2007) which connects the Danube and the Black Sea. The goal of the technical works was to recalibrate the Bîstroe riverbed (widening the bed and substantially enlarging the slope of the riverbed). Subsequent hydrological research has shown that there are strong influences on the reduction of liquid and solid runoff on the Bîstroe Canal (between Periprava and downstrem of confluence of Stambulul Vechi). The present climate change is largely attributed to anthropogenic activities that alter the composition of the atmosphere and add to the natural variability of the climate. Due to the greenhouse effect, there is a general increase trend of the air and water average temperature with implications for other environmental components. Other effects are related to the exacerbation of the extreme phenomena—heat waves, droughts, storm-related precipitation, flash floods, etc. Local pollution is added to all of these affecting ecosystems and together with human systems as burning of

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fossil fuels both locally reduced air quality and globally increase in greenhouse concentrations [4]. The regional climate response to the global warming signal is modulated by local factors such as: the presence of the Carpathian arc, the vicinity of the Black Sea, the diversity of soil and land cover types, the complex hydrographic network. Floods are the most destructive natural phenomenon in the world [5–7]. Among the European countries most frequently affected by recent floods are the United Kingdom, Romania, Germany, etc. [8]. For Romania, meteorologists’ studies indicate an increase, of the country’s average of the annual temperature of about 1 °C, from the beginning of the twentieth century [9]. Following the hydrological analysis performed at the Danube hydrometric stations for the 1985–2018 period, there is a certain tendency to increase air and water temperature, the number of days when the water temperature is higher than 0 °C and a certain decrease of the winter phenomena duration. It is possible that in the Danube meadow and the Danube Delta area, the extreme phenomena to be amplified by periods of more intense floods and longer dry periods, with consequences on the hydrological regime of low waters, which may manifest differently at local and regional level. During the last 10 years, natural disasters have become more frequent. For example, within 2005–2010 were recorded, the highest values of the Danube level in the last 100 years. From this perspective, the consequences of climate change, predicted by specialists, will have significant impact on the unique biodiversity of the Danube Delta.

2 General Presentation of the Danube Delta The deltaic zone represents the maze of canals of the Danube River in its branches, to its outflow into the sea. It can be divided into the fluvial deltaic subarea and the fluvio-marine deltaic subarea, or in the subarea of the main branches (Chilia, Tulcea, Sulina, Sfântu Gheorghe) and the subarea of connecting channels and small branches. In 1928, the Hydraulic Service of Romania, with the help of the Danube Fishermen’s Division, conducted a large program of hydrometric activity, especially on the Chilia and Sfântu Gheorghe branches, where the lack of data was almost complete. For this purpose, between 1928 and 1934, a series of new hydrometric gauge stations were established at the same time series. Carrying out some researches between 1856–1857, were made the first measurements of the Black Sea Level at the mouth of Sulina and Sfântu Gheorghe branches, establishing the reference plan “0” (zero meter) Black Sea Sulina, materialized on the foundation of the central lighthouse in Sulina (still existing today), with a metal marking located at the elevation of 4.88 feet (1.4874 m) above the reference plan. Compared to the reference plan, all the hydrographical works and hydrological measurements carried out in the Danube Delta and on the Danube were reported, being used so far. In the Danube Delta, expeditionary measurements are carried out by Tulcea hydrological station (on the Danube River between 80 and 140 km, on the Chilia and

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Sfântu Gheorghe branches, the gorge, canals and lakes of the Danube Delta, as well as the Razelm-Sinoe lagoon complex) and Sulina hydrological station (on Sulina branch and in the river-marine area of the Danube Delta). The measurement program includes two types of activities: regular stationary measurement (daily measurement of water level, discharge, air and water temperature, suspended matter concentrations) and expeditionary measurements (4 or 6 measurements/year of water discharge, bathymetric measurements and sediment discharge). The network for monitoring the hydrological regime in the delta is a fairly well developed one consisting of 14 basic gauge stations (Fig. 3), with a complex monitoring program. The water flows of the Danube River are divided on the three main channels, in the following variable proportions, over the time: from 73 to 50% (in present) on the Chilia canal, from 7 to 20% (in present) for Sulina branch and from 20 to 30% (in present) on the Sfântu Georghe canal [10]. Between the main Danube branch, there is the secondary hydrographic network consisting of many channels and secondary, navigable canals, which introduce and distribute water flows, mineral salts and sediments in the Danube Delta, communicating with the main channels, the lake areas and the areas located at south of the Sfântu Gheorghe branch (Razim-Sinoe lagoon complex).

Fig. 3 Location of the basic gauge stations on the main branches of the Danube Delta

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3 Water Level Variability on the Danube Delta Branches Following the analysis of the long series of values of the multiannual monthly average, minimum, maximum water levels, it was found (Fig. 4) that the highest values are usually reached in April–May, when the water supply in the delta is excessive, coming from rains and from upstream runoff. The lowest values are observed in autumn (September–October) due to the installation of hydrological minimums on the entire Danube River Basin. Analysis of the water levels variability at the main hydrometric stations on the Chilia, Tulcea and Sulina channels was performed based on the series of daily average values, that are obtained on the ground of two daily readings of the level at the hydrometric staf. It is found that the water level (Fig. 5 and 6), expressed in absolute elevations (m) compared to the “0” plan in Sulina (Sulina Black Sea Reference System) has an increasing trend at all hydrometric stations. The hydrological impact on the Danube Delta depends on the extent of the hydrotechnical arrangements and the dredging works carried out at the Danube’s branches mouths [3]. Water levels evolution highlights the existence of a close connection with the hydrological regime phases, that led to water levels amplitudes exceeding 200 cm, from one year to another, on a large part of the Chilia branche (at Ceatal Izmail and Chilia Veche stations), of the Tulcea branch (at Tulcea Port station) or of the Sulina canal (at Ceatal Sfântu Gheorghe station). The differences between the annual maximum and minimum water levels is varriable between 2.5 and 4.4 m at Tulcea Port, 1.5 and 2.5 m at Chilia Veche and 0.5 and 1.5 m at Sfântu Gheorghe’s stat, ions (Fig. 7). Starting with 2002, there is a slight increasing tendency in these values, at all analyzed hydrometric stations, without significant differences between years.

Fig. 4 Variation of the average, minimum and maximum monthly multiannual levels in 1985–2018 period at Tulcea Port gauge station (Tulcea branch)

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Fig. 5 Variability of the annual average water levels H (m) during 1985–2018 period—at gauge stations Tulcea Port, Ceatal Sf. Gheorghe and Sulina Port

Fig. 6 Variability of the annual average water levels H (m) during 1985–2018—at Ceatal Izmail and Chilia Veche gauge stations (Chilia branch)

4 Hydrological Water Regime on the Danube Delta Branches The hydrological and hydrochemical processes that take place in the Ceatal Izmail hydrographic network node, on the Danube, are important for the drainage of water, mineral salts and sediment into the Danube Delta. Many of the characteristics of the biotope and deltaic biocenosis, depend on the hydrological and hydro chemical processes that take place in this area. Figure 8 shows the topological diagram of the Danube Delta and the sketch of the location of the Ceatal Izmail hydrometric section.

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Fig. 7 Range of variation of the annual characteristic water levels (max and min), for the period 1985–2018 (gauge stations Tulcea Port, Chilia Veche, Sf. Gheorghe)

The average multi-annual flow at the entrance to the Danube Delta (Ceatal Izmail gauge station), calculated for 1985–2018 period, is 6205 m3 /s, with a maximum daily value of 15,900 m3 /s produced on April 25, 2006 and a minimum daily value of 1870 m3 /s produced on October 10, 1992. During the same period, the average multi-annual flow at the mouths of the three Danube branches in the Black Sea is 5929 m3 /s. The difference of 276 m3 /s between the two values of the flow is

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Fig. 8 Topological scheme of the Danube Delta and location of the Ceatal Izmail hydrographic node

due to several factors (penetration of water inside the delta, evaporation and water discharges into the Black Sea in other ways than the Danube branches mouths). For the analyzed period of time, the variation of the annual average flows (Qmean ) of the Danube, measured on the main branches of the Delta, shows a tendency of increase compared to the multiannual average discharge, especially in the last 15 years (Fig. 9). It highlights the dry years (1990, 2003, 2011, 2012) and the rainy years with exceptional floods (2005, 2006, 2010). Due to the continuous hydrotechnical works accomplished before 1985, as it was mentioned briefly in the Introduction chapter, the discharge repartition on the Ceatal Izmail hydrographic network node, between Chilia and Tulcea channels has suffered modification over this time interval. In the last few years an equal share of flow (50%) is distributed on each channels (Fig. 10). Concerning the hydrographic node on the Tulcea channel (Ceatal Sfântu Gheorghe), the discharge is divided on the Sulina and Sfântu Gheorghe canals. In Fig. 11 is represented the water flows distribution on the two channels of the Danube Delta and their evolution trends. For the hydrological regime of average flow, the discharge repartition has a decreasing tendency on the Sulina Canal and increasing tendency on the other channel. The increase of the flow on the Sfântu Gheorghe branch was influenced by the hydrotechnical works for the rectification of the riverbed (meanders cuttings), in the early 90s, which led to the increase of the slope and of the average water velocity, compared the period of the natural regime. Extending the analysis of the variability of the water flow on the Chilia canal, it is found that by moving away from the hydrographic nodal dispersion point of the Danube (Ceatal Izmail gauge), the oscillations of flow values from an year to another becomes smaller, exceeding 2500–3500 m3 /s only in years with higher floods (e.g. 2005, 2006, 2010). Analysis of the runoff on the two extreme phases of hydrological regime (minimum and maximum) highlighted the connection of the main branches with

Fig. 9 Variation of the annual average flow during the 1985–2018 period on the main branches of the Danube Delta. Comparison with the multiannual average flow

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Fig. 10 Temporal variation of the distribution of annual average flow in the Danube Delta, during 1985–2018 period (on Chilia and Tulcea branches)

Fig. 11 Temporal variation of the distribution of annual average flow, inside the Danube Delta, during the 1985–2018 period (on Sulina and Sfantu Gherghe channels)

the wetland inside the Delta, the water exchange being made permanently to and from the Delta (Fig. 12). Generally, the discharge at the entry of the Delta decreases progressively towards the outflow of the Danube into the Black Sea. The channels feed the Delta (Qoutput < Qinput ), a situation that is not always encountered in the case of the “high water” hydrological regime, especially for the Sulina channel, when during important floods Delta feeds the Sulina channel (Qoutput > Qinput ). In the last 10 years, there has been a tendency towards modification of the water flow to and from the Delta’s canals. The difference between the input/output flows on the Chilia and Sfantu Gheorghe canals decrease over time, by increasing the water supply from Delta to the. An increasing input/output ratio is observed in the case of

Maximum flow

Fig. 12 Variation of the minimum and maximum flows measured at gauges located at the entrance and exit of the Chilia, Sulina and Sfântu Gheorghe branches, during the 1985–2018

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Sulina canal (water is released in the Delta and the discharge at the Sulina’s mouth is smaller), which is a favorable situation for the ecosystem situated next to the canal. In the case of important decrease of flow and water level (e.g. 1990, 2003) it may happen that the lakes and other humid areas inside the Delta receive no longer fresh water, so, the water quality to worsen and as a result the aquatic organisms inside the lake may suffocate due to oxygen lack in the water [3]. From this perspective, global warming that may induce prolonged droughts is extremely dangerous for the Danube Delta ecosystem.

5 Hydrological Extreme Phenomena 5.1 High Water Regime in Danube Delta As part of the hydrological hazards, extreme phenomena such as floods represent a major danger for the localities in the Danube Delta. Concerning the Danube meadow, Danube Delta and the Black Sea coastal area, floods have been a major source of material damage, human casualties and destruction of property, over the time. In the last 100 years, significant floods with maximum flows that exceeded 14,000 m3 /s, at the entrance to the Danube Delta (Ceatal Izmail station) were registered in 1940, 1942, 1970, 1980, 1981, 2005, 2006 and 2010 years. The maximum flow recorded at the entrance to the delta in April 2006 (Qmax = 15,900 m3 /s) reached historical values, being higher than those recorded in 1970 year (Qmax = 15,540 m3 /s) or 1980 year (Qmax = 14,600 m3 /s), and very close to the flow with the probability of exceeding 1%. After the distribution of the waterflow on the Tulcea and Chilia canals (at Ceatal Izmail), the values recorded in 2006 and 2010 on the Tulcea channel were the largers in the history of measurements, both in terms of maximum recorded daily flows and water levels (Qmax = 7590 m3 /s, Hmax = 437 cm in 2006; Qmax = 7450 m3 /s, Hmax = 438 cm in 2010), as well as the very long duration of the levels that exceeded the Alarm levels (flood and attention quotas) (Fig. 13). The two significants events are different from each other, from the following points of view: • number of floods peaks (alarm quotas were exceeded one long period in 2006 and four short periods in 2010); • duration and period of floods occurrence: 34 days, during April–May months (in 2006) and 16 days, during June-July months (in 2010); • volume of water transported along the branches—777*109 m3 (2006) and 889*109 m3 (2010). The damage caused by the floods in 2010 were more significant than in 2006. When water levels exceed normal values, the most affected by floods are the localities located on the main branches of the Danube Delta. In the two analyzed years, many agricultural lands and localities were flooded (e.g.: Mahmudia, Ceatalchioi, Crisan

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Fig. 13 Variation of average daily levels for 2006 and 2010 years, at the Tulcea Port gauge

etc.). Also, the Sireasa agricultural development was severely affected by this flood, which caused significant damage to the localities inside the agricultural unit, and the arable land in the area [11, 12]. Two other significant hydrological events for the Danube Delta ecosystem recorded in the analyzed period of time were those of 2005 and 2018, with very similar values of water flows and maximum daily levels (Qmax = 6660 m3 /s, Hmax = 401 cm in 2005; Qmax = 6700 m3 /s, Hmax = 403 cm in 2018), but even different in terms of development in time and volume of water transported (Fig. 14). The

Fig. 14 Variation of daily average discharges in 2006 and 2010 years, at the Tulcea Port gauge section

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Fig. 15 Variation of the maximum annual water flows in 1985–2018 period at the entrance to the Danube Delta (Ceatal Izmail station on Danube)

mentioned events did not cause flooding. The consequences of significant floods, such as those mentioned above, show that the delta area is particularly vulnerable to this risk. The evolution of the maximum annual flows of the Danube, at the entrance to the Delta (Ceatal Izmail on the Danube), in the analyzed period of time, is characterized by an increasing trend (Fig. 15). The multiannual average of the maximum annual water flows, for 1985–2018 period, at Ceatal Izmail station is 11365 m3 /s. Statistical calculations have shown that there is a certain periodicity of variation in time of the maximum annual water flows, which in the case of the Delta varies between 9 and 31 years [13]. On the base of statistical analysis of the maximum annual water flows, it was aimed at determining the frequency of the number of events that occurred in a certain class of values. For this purpose, the data series was divided into equal intervals of flow values. According to the number of cases obtained for each flow interval (absolute frequency), the highest frequency flow class was identified. The comparative analysis of the last 10 years (2009–2018) compared to the 34 years (1985–2018) was done using relative frequency (percentage). A move of the highest frequency to the class of values with higher flow rates was passed (Fig. 16). The result of the analysis indicated that in the last 10 years the frequency of the number of cases in a certain class of flows has changed. In the case of Ceatal Sfântu Gheorghe hydrometric station (Tulcea branch), the highest frequency has changed, from one class of values of flows (between 4000 and 5000 m3 /s, during 1985–2018 period), to another (between 5000 and 6000 m3 /s, during 2009–2018 period). In the case of Ceatal Izmail hydrometric station (Chilia branch), it was obtained the increase of the share of the flow class with the highest number of cases: from frequency 35 to 40% for class 5000–6000 m3 /s.

5.2 Low Water Regime in Danube Delta The minimum runoff can be considered as a characteristic of surface water. The main driver of the formation of minimal runoff is the rainfall deficit, together with

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Fig. 16 Comparative analysis of the temporal evolution of the frequency of the annual maximum flow classes for 1985–2018 and 2009–2018 periods

factors such as high air temperature, strong sun, small cloud cover, and a high level of evaporation at the water’s surface. In the last 100 years, the minimum annual flow, at the entrance to the Danube Delta (Ceatal Izmail station), reached an hystorical value in 1921 (Qmin = 1350 m3 /s) which represents less than half of the multiannual minimum flow calculated over the analysed period of time (Qmin = 2997 m3 /s). The study of the low flow on the main Danube branches, showed that in the analyzed period of time (1985–2018) lowest annual minimum flows were recorded, in 1990, 2003, 2011and 2018 years (Fig. 17) in September, October and November. Starting with 1992, after the completion of the hydrotechnical rectification of the Sf. Gheorghe branch, the values of the minimum annual flows on the Sulina and Sf. Gheorghe branches began to differentiate by increasing the water flows on the Sfântu Gheorghe branch due to the increasing of the riverbed slope. The lowest minimum annual flows varied from 895 m3 /s (11.09.1990) and 975 m3 /s (05.09.2003), to 1100 m3 /s (29.11.2011) and 1300 m3 /s (26.10.2018) (Fig. 17 and 18). During the time, the date of occurrence of the minimum flow is delayed towards the end of the year.

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Fig. 17 Variation of annual minimum flows during the period 1985–2018 for the gauge stations on the Ceatal Sf. Gheorghe hydrographic node

Fig. 18 Variation of average daily flows in years 1990, 2003, 2011, 2018 (years with low water level at Tulcea Port gauge station)

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Ceatal Sf. Gheorghe (Tulcea branch) 7000 6000 5000 4000 3000 2000 1000 0 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018

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Fig. 19 Temporal evolution of the range of variation of the average daily flows in 1985–2018 on the Tulcea channel (Ceatal Sfantu Gheorghe gauge station)

The graphs highlights the change over time of the variation interval of the average daily flows (the range of values between the extreme values Qmax and Qmin ). The analysis of the range of variation, for the average daily flows, shows an increasing tendency during the period 1985–2018 (Fig. 19). The result indicated that starting with 1990 (the year with the smallest range of variation), the enhancement of the intensity of range variation was accompanied by intensity of floods and droughts. Significant values of maximum and minimum flows in 2006, caused the largest range of variation of the daily flow (5890 m3 /s). The statistical analysis of the minimum annual water flow, by intervals (classes) of flows, indicated that even for the minimum runoff, in the last 10 years, the frequency of some classes of flows has changed. The same type of analysis, as the one for high waters, was conducted for the low flow data series, corresponding to the two periods of time 1985–2018 and 2009–2018 respectively. The minimum annual water flow values were distributed into equal intervals of flow values. According to the number of events occurred for each flow interval, the highest frequency flow class was identified and then, the analyse of the two periods of time was conducted using relative frequency (Fig. 20). The results indicated that the highest frequency moved to flow classes with lower values. It is the case of Ceatal Sfintu Gheorghe hydrometric station (Tulcea branch): highest frequency changed from the interval 1500–2000 m3 /s (in the period 1985– 2018) to the interval 1000–1500 m3 /s (in the period 2009–2018). For other gauge stations, as is the case with the Ceatal Izmail hydrometric station (Chilia branch), the study shows the increase of the share of flow class with the highest frequency (from 47 to 80% for the flow class 1000–1500 m3 /s).

6 Air and Water Temperature Variation From a climatic point of view, the Danube Delta falls into the space with a temperate climate, semi-arid specific to the Pontic steppes. The flat and very wide aquatic spaces, present in the delta, are covered (in different proportion) by vegetation, being

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Ceatal Sf. Gheorghe (Tulcea branch) frequency from total events (%)

60 1985-2018 2009-2018

50 40 30 20 10 0 • Inhabitants of B˘altenii de Sus >• Tulcea County Council >• Tourism industry >• Fishermen >• National Administration of Romanian Waters >•National Agency for Protected Natural Areas >• Danube Delta Biosphere Reserve Administration (DDBRA) >• Danube Delta National Institute for Research and Development (DDNIRD) >• National Institute for Marine Research and Development “Grigore Antipa” >• People that are involved in eco-agriculture

>• Private investors >• SME >• Farmers >• Persons from the private sector >• People with Industrial fishing >• People doing animal husbandry >• Mayors of local communities >• People who support urban development >• Some political parties in the delta administration >• Concessioner of agricultural polders >• Civil servants >• Animal herders >• People who do not know the details

Fig. 5 Percent of interviewees that claimed the subjective factor

interviewees. Almost 30% of the people considered the farmers, herders, academic institutes and the private sector as their referent group of stakeholders. Apart from these, the other groups of stakeholders influenced less than 20% of the people.

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Fig. 6 Percent of interviewees that claimed a PBC factor

3.3 Perceived Behavioural Control A major difficulty for the interviewees from the local community was the lack of awareness about NBS (Fig. 6). According to them, this will make the adoption of NBS challenging for people. Furthermore, around 30% believed that the cause of this knowledge gap was the lack of research in the field of NBS. Loss of land was a constraint for 20% of the people and therefore one-third of the interviewees stressed that without the availability of satisfactory compensation systems, NBS will be arduous for some groups of stakeholders. Around 10% also claimed that it is important to identify appropriate lands for implementing NBS to avoid stress on land-owners. Additionally, other major concerns that may pose a challenge according to the people in the delta are the lack of coherent legislation on NBS, stubborn mentality, higher cost of implementing NBS, etc. Only a little less than 20% of the stakeholders did not project any difficulties associated with the adoption of NBS.

3.4 The Sustainability of the Behavioural Change While evaluating if a project is capable of initiating a behavioural change, it is important to understand from the beginning if there is a positive intention amongst the stakeholders to adopt the changes. This intention is developed on three factors: attitude, subjective norm and perceived behaviour change [21]. If all three factors have only positive components (Fig. 7), it will lead to the intended behavioural change. So, suppose the locals believe that there will be beneficial consequences of

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Fig. 7 A behavioural change is possible with stakeholders if the 3 behavioural factors are positive

NBS, which are promoted to them by their referent groups of stakeholders. In that case, they will develop a positive intention to adopt the NBS as long as they do not face any challenges. This generated intention will then guide the locals to perform actions that will support the NBS. On the contrary, if only the negative components of the three factors are considered, this will not result in a behavioural change as seen in Fig. 8. When the locals consider only the negative consequences of NBS which are supported by the people who oppose NBS and there are many challenges to accept the changes, there will not be an intention in the society to adopt the proposed intervention. This means that the locals will oppose the project and refrain from changing their current lifestyles. The two aforementioned scenarios consider two extreme reactions of the stakeholders. However, in reality, behavioural change in the Danube Delta will be a combination of both scenarios. According to the interviews conducted, most of the residents (except the farmers and livestock breeders) and decision-makers perceive that the NBS will bring a positive change to the delta (Fig. 4). Further, the stakeholders are also supporters of NBS (Table 3). This ensures that the locals gain confidence in the interventions as they are promoted by their referent groups of stakeholders. This shows that for a majority of the stakeholders, the Attitude and Subjective Norm factors are positive. However, according to the interviewees, various challenges still exist that hinder the uptake of NBS (Fig. 6), making the PBC factor negative. While the prior two factors can generate a positive intention towards NBS, this intention

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Fig. 8 A behavioural change is not possible with stakeholders if the 3 factors are negative

will be unsustainable due to the negative PBC factor. Therefore, although the stakeholders perceive NBS as beneficial and have confidence in the intervention, they will not be motivated to change their behaviours due to the difficulties of adopting NBS.

4 Conclusions and Recommendations The study aimed to analyse the necessary framework for a behavioural change of the Danube Delta key stakeholders in applying the NBS for tackling local society challenges. Conclusions and recommendations resulting from The Behavioural Change Evaluation Framework are summarised in three most important components: attitudes, social norms and perceived behavioural control. Increase in tourism is a crucial consequence to many stakeholders of the Danube Delta in terms of the locals’ attitude towards NBS. Therefore, the implementation of NBS in this area should support tourism and tourist related activities. The study revealed as a social norm that the locals rely on the decision makers as their main source of information on NBS. It is important for the locals to have more information on NBS from mayors and other civil servants. A gap between the local authorities, NGOs representing the professional associations and private sector who lack knowledge about NBS and the institutes responsible to spread this awareness was identified as part of the perceived behaviour control.

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Despite the presence of various institutes and research organisations in the Danube Delta, the interviewees perceive the disparity in knowledge as the main challenge for initiating and implementing NBS. Majority of the stakeholders interviewed claimed that they rely on DDBRA to gain information but it lacks in initiatives. This study concludes that the institutions and organisations that the locals rely on for information are unable to guide them about NBS. This could be due to lack of initiative from the institutions or it could be as they do not possess mediums to transfer the knowledge. This gap could be a major hindrance in gaining the confidence of locals in NBS. The proactiveness and involvement of the institutions and organisations in NBS initiatives would be the main elements in enabling the behavioural change towards implementing NBS at larger scale in the Danube Delta to solve the local ecological and societal challenges.

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Climate Suitability for Sustainable Economic Growth Through Tourism in the Danube Delta Adina-Eliza Croitoru, Adina-Viorica Rus, Titus-Cristian Man, Victor Malair˘au, and Alexandru Matei

1 Introduction The tourism industry is one of the largest and most profitable economic sectors worldwide, recording spectacular growth in recent decades while being among the most influenced by climate [1]. As a climate-dependent sector, many destinations owe their popularity to their pleasant weather during traditional holiday seasons [1–3]. Tourists’ choice of a holiday destination is conditioned by the climate, which influences the holiday period and outdoor tourist activities’ attractiveness [3]. In general, A.-E. Croitoru Department of Physical and Technical Geography, Faculty of Geography, Babes, -Bolyai University, 5-7 Clinicilor St., 400006 Cluj-Napoca, Romania e-mail: [email protected] Research Centre for Sustainable Development, Faculty of Geography, Babes, -Bolyai University, 5-7 Clinicilor St., 400006 Cluj-Napoca, Romania A.-V. Rus Department of Political Economy, Faculty of Economics and Business Administration, Babes, -Bolyai University, 58-60 Teodor Mihali St., 400591 Cluj-Napoca, Romania e-mail: [email protected] T.-C. Man (B) Department of Regional Geography and Territorial Planning, Faculty of Geography, Babes, -Bolyai University, 5-7 Clinicilor St., 400006 Cluj-Napoca, Romania e-mail: [email protected] Centre for Regional Geography, Faculty of Geography, Babes, -Bolyai University, 5-7 Clinicilor St., 400006 Cluj-Napoca, Romania V. Malair˘au · A. Matei Faculty of Geography, Babes, -Bolyai University, 5-7 Clinicilor St., 400006 Cluj-Napoca, Romania e-mail: [email protected] A. Matei e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_11

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the tourists’ decision for trips to various destinations depends on the season, with incoming flow intensity increasing or decreasing connected directly to the weather conditions [1, 4]. General climate plays a crucial role in the success and sustainability of a particular region’s tourism sector. Tourism develops only if the tourists perceive it as appropriate and decreases in intensity with the increase of climatic discomfort. A favorable climate is considered a tourism resource, along with topography, geographical location, landscape, flora, and fauna [5]. In addition to the key role it plays in the adequacy of a destination, the climate also significantly influences the rest of the destination’s natural resources. Climate and weather conditions often prevail over other competitive factors [6], as they are among the critical ones in the tourists’ satisfaction during their stay [2, 3, 7]. Therefore, destinations with higher quality climate resources than others have a competitive advantage. The local climate often outlines the tourist seasonality. It is a triggering factor in the sustainability of the tourism sector. At the same time, the daily changes in weather conditions can imply the tourists’ satisfaction by changing the daily schedule during a stay [2, 3, 8–13]. Often, tourists suffer from extreme weather events during their holidays, such as cold rains, violent winds, heat, etc. [14]. From an economic perspective, regions with high variability in weather conditions are not profitable since substantial financial losses can be generated due to unexpected severe weather [5]. However, all stakeholders in the tourism sector (tourists, tourism guides, travel planners, and travel agencies) must be informed about the importance of weather and climate in developing a particular destination [15]. Accurate information is necessary on the current climate adequacy for the development of the tourism sector [16, 17]. A standardized and compliant approach is required to understand both the relative strengths and disadvantages of a given tourism region and quantify climate adequacy relative to competing areas [12]. The complexity of establishing the influence of climate on tourism is high because a single climate indicator cannot wholly describe the climate conditions in a particular destination [5]. Tourists perceive the integrated effects of climate, imposed by the combined action of several parameters such as precipitation, temperature, wind, humidity, and sunshine [5]. To assess the climate conditions in a specific region is recommended to use indices that integrate more climate variables that can provide conclusive information about the tourists’ preferences and, therefore, the appropriate conditions for sustainable tourism development [18, 19]. During the traditional peak season for holidays, sometimes popular destinations are exposed to high tourists’ pressure regarding the environment and the local population. Consequently, the application of tourism comfort indices for detecting possible extension of the season and decreasing the peak flow can improve the decision-making process for stakeholders in a particular region with substantial implications for the economy. In the second half of the last century, researchers worldwide developed many indices to quantify the climate influence on the tourism sector [19–24]. The Climate Tourism Index (TCI) proposed by Mieczkowski in 1985 is a globally adopted method for analyzing the complex relationship between climate and tourism and determining the climate suitability for a destination’s outdoor tourism. It is one of the most comprehensive indices to assess the appropriate climate conditions for outdoor tourism, as it

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integrates those issues considered important for tourism: thermal comfort, physical aspects such as precipitation and wind, and the aesthetic part, quantified by sunshine hours [7, 25, 26]. It was globally used for assessing climate suitability for tourism for both present and future climate conditions [7, 27–34]. Beyond the climate and natural resources, accommodation infrastructure and accessibility of a place or a location is a critical factor for tourism and a region’s economic competitiveness. Regional planners and transportation academics have long been concerned with the social, environmental, and economic consequences of accessibility. Even though there is no broad agreement on its definition [35, 36], the concept of accessibility is applied in data science since it is a direct manifestation of mobility [37, 38]. It expresses the efficiency to which some specified activities (opportunities) can be achieved via a transportation system from a given location [36, 39]. The concept of peripherality is widely used to designate places with low levels of accessibility (particularly to economic activity, including tourism) [36, 40]. Accessibility assessment has been divided into a variety of categories throughout the academic literature. Different approaches have been considered: isochrones (based on commute time, distance, and cost from origin to destination), gravity-based measures (correlation between accessibility and journey time to destination), and utility-based values (economic benefits of a place derived from accessibility) [35]. Even though it is scientifically very well-known worldwide, the focus region of this study, the Romanian sector of the Danube Delta, is relatively underdeveloped from an economic perspective and is part of one of the poorest regions in Romania and Europe. It has a poverty rate of about 30%. Often, the inhabitants from isolated villages of the Danube Delta live in poverty or near-poverty conditions [41, 42] due to the natural conditions and isolation. Under these circumstances, this research has three objectives: to (1) assess the climate suitability for a possible extension of the season for outdoor tourism by using an enhanced version of the TCI (ETCI), (2) analyze if occupancy rates in the accommodation structures (and other related economic indicators) correspond to local weather conditions, and (3) propose two development scenarios for sustainable economic growth based on tourism in one of the most famous protected area in Europe.

2 Material and Methods 2.1 Data Used 2.1.1

Climate Data

For this study, daily and sub-daily climate data over an 11-yr period (2010–2020) recorded in four weather stations belonging to the Romanian National Meteorological Administration (NMA) were employed to calculate the daily values of the ETCI. They cover quite well the Danube Delta region: one of them is located on the western limit

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of the natural reservation (Tulcea), one is inside the delta (Gorgova), and two are located in the extreme east of the region covering the Black Sea seaside, too (Sulina and Sfantu Gheorghe-Delta). The geographical coordinates of the weather stations are listed in Table 1, and their position is presented in Fig. 1. Table 1 Location of the weather stations considered for this study No.

Weather stationa

Latitude (°N)

Longitude (°E)

1

Gorgova

45.1769444

29.1566667

3.5

4.64

2

Sfantu Gheorghe-Delta

44.8977778

29.5991667

2

6.65

3

Sulina

45.1483333

29.7588889

13.2

3.12

Tulcea

45.1905556

28.8241667

5

0.4

4 a The

Altitude (m)

Missing data (%)

weather stations are listed in alphabetical order

Fig. 1 The Danube Delta location and weather stations used for ETCI analysis

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Even though some other weather stations are settled in the focus region, we have decided to use only those where missing data did not exceed 7% over the considered period. However, three out of four weather stations have more than 95% coverage, and only at Sf. Gheorghe-Delta missing data recorded 6.65% (Table 1). We decided to keep it because it is the most representative for the seaside sector of the Danube Delta. To calculate the ETCI, we used daily values: maximum and mean air temperature (TX and respectively TG), minimum and mean relative humidity (RHN and RHA), sunshine hours (S), wind speed (W) calculated at 1.2 m height, and amount of precipitation (R). The datasets were constructed from data derived from three databases. Most of the data were freely downloaded from the Meteomanz [43], Reliable prognosis 5 days [44], and OGIMET [45] databases. We extracted the daily TX with its corresponding RH and W from hourly datasets. Mean daily values for the other parameters (TG, RHA, P, S, and W) were derived from the daily datasets available in the databases mentioned above. The daily S for 2010–2013 were extracted from the ROCADA database [46].

2.1.2

Economic Data

To analyze the Danube Delta tourism from an economic perspective and to calculate the development potential preserving at the same time the natural ecosystem, we used data sets describing the tourism-related activity and the economic actors’ financial performance in the focus region. We intended to choose the same period that aligns with the weather data (2010–2020). However, because 2020 was heavily influenced by the COVID-19 pandemic restrictions (total lockdown in the entire country between March and May, limited but growing activity in June and July, and intense activity in August and September), we excluded the 2020 tourism activity data from the economic analysis. We only considered the 2020 accommodation data for forecasts and simulations. The tourism sector data is freely downloadable from the TEMPO database from the Romanian National Institute of Statistics (www.insse.ro). The economic data regarding annual turnover for each settlement was obtained from a database containing almost 1000 indicators proposed by the World Bank for the evaluation of Romanian urban areas [47] and was available only before and 2018. Two sets of indicators were employed to assess the economic issues in the focus region: • Three general economic indicators were analyzed: number of employees, number of companies, and turnover; for an accurate analysis, only the economic players with the activity object related to tourism—accommodation providers, restaurants, and tourism agencies—were selected. • Three specific indicators for tourism activity were considered: number of overnight stays, number of available accommodation capacity (as reported by the accommodation infrastructure owners to the overseeing regulatory agency),

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and number of tourists arrived in the region (used indirectly to calculate the economic value for a tourist). Accommodation infrastructure includes tourist reception structures with tourist accommodation functions - any construction or arrangement that permanently or seasonally provides accommodation service and other specific services for tourists. We considered only those tourist reception structures with an installed accommodation capacity of at least five places. They include hotels, youth hotels, hostels, apart-hotels, motels, inns, tourist villa, tourist cottages, hunting, and fishing cottages, bungalows, holiday villages, camping, cottage type tourist units, student and preschool camps, agrotourism pensions, tourist pensions, apartments or rooms for rent and accommodation on the sea and river ships. As accessibility to a destination is extremely important, we considered for this study a specific analysis on this topic, too. To efficiently assess the level of accessibility in the Danube Delta, we considered journey time from any Romanian settlement to the nearest central place of each rank using the road network. We employed all currently categorized roads by the Ministry of Regional Development and Public Administration in 2020 and updated them with OpenStreetMap data.

2.2 Method 2.2.1

Enhanced Tourism Climate Index (ETCI)

Currently, environmental information is very easily accessible on a large scale and in various forms, especially on the Internet. But only access to information does not ensure the expected effect at the destination. It must be processed and arranged in a form relevant to local stakeholders. On the other hand, they must have the intellectual capacity and technical expertise to use the information effectively [5]. Since tourists react to numerous cumulative climatic variables [19, 26, 48], we decided to use for this study the TCI to assess the climate suitability as it is complex enough to cover the interaction among different climate variables (temperature, humidity, precipitation, wind speed, and sunshine hours). It is one of the most employed indices to evaluate the climate conditions for tourism suitability worldwide. However, we did not used it in its basic form, but an enhanced version (ETCI). Developed in 1985 by Mieczkowski [18], and sometimes named as the “universal tourism climate index”, the TCI has been employed for many regions of the world in its basic form as it is very comprehensive. However, data availability and the limitations identified in the original formula imposed some adaptations and/or changes presented by different authors [5, 7, 15, 25, 49, 50]. One of the most important modifications of the original formula is the temporal scale used for the basic TCI calculation. Monthly averages of the climatic parameters originally applied are quite irrelevant for real tourism climatic purposes. Usually, tourists’ stay in a specified destination is much shorter, varying in general from

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7 to 10 days. For tourists, it is essential to know the risk factors for their stay, respectively the weather impediments that can occur daily, such as heavy rainfalls or thunderstorms [7, 25, 49, 51, 52]. This paper addressed this limitation by enhancing the original version of the index. We used daily data and outlined ten-day periods for the final classification of climate adequacy for outdoor tourism. For a more accurate analysis and considering an average duration of a vacation of 7–10 days, we identified the suitability for outdoor tourism and recreation for every ten days (decade), beginning with January 1 to December 31. Three sub-periods for each month were derived. To keep as simple as possible the evaluation, for 28, 29, or 31-day months, we considered the last decade of each month to begin on the 21st day and end on the last day. This procedure was also employed, with good results for Eastern Romania [13]. Determining the daily TCI allows quantifying the number of favorable days during the month, too. Another limitation of the original version of the TCI is employing effective temperature (ET) for thermal comfort, which considers temperature and relative humidity only [7, 8, 49, 53]. Some of the authors mentioned above replaced it with apparent temperature [54] or physiologically effective temperature (PET) [49]. For this paper, we used the thermal comfort calculated based on effective temperature (TE) [55] which evaluates the joint influence of air temperature, wind speed at 1.2 m from the ground level, and relative humidity of the air. The index establishes a relationship between the identical state of the human body’s thermoregulatory capacity (warm and cold perception) and differing temperature and humidity of the surrounding environment [55]. It is calculated based on Eqs. (1) and (2), depending on the wind speed values [56]. • for v ≤ 0.2 m/s:

TE = T − 0.4 × (T − 10) × (1 − 0.01 × RH)

(1)

• for v > 0.2 m/s:     TE = 37 − (37 − T)/ 0.68 − 0.0014 × RH + 1/ 1.76 + 1.4v0.75 − 0.29 × T × (1 − 0.01 × RH)

(2)

where, T - the air temperature (°C); v - the wind speed (km·h-1 ); and RH - the relative humidity (%). For wind speed conversion from 10 m altitude (v10m) to 1.2 m (v), we used the formula for wind speed extrapolation (3), available on: https://websites.pmc.ucsc. edu/~jnoble/wind/extrap/ [57].

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V =V×

ln ZZ0 ln

(3)

Zr e f Z0

where, V - velocity to be calculated at height Z; Z - height above ground level for velocity V; V ref - known velocity at height Zref ; Z ref - reference height (10m) where V ref is known; and Z 0 - roughness length in the current wind direction. The reclassification from TEd and TEa to the rating score introduced in the final ETCI formula was maintained as in the original version of the index (for CId and CIa). For precipitation (R), we gave scores for each day: the monthly values established by Mieczkowski [18] were divided by 30, and thus, we got the daily threshold for each rating class. The negative impact on tourist satisfaction caused by severe weather may be more significant than positive experiences due to favorable weather conditions, leading to long-term implications for a tourist destination due to the short-term impact of adverse weather events [2, 3, 9–11, 58]. For this reason, we added two more classes for precipitation evaluation: for heavy rainfall days (10–20 mm/day) or extremely rainfall days (exceeding 20 mm/day), we gave exceptional negative scores of -1, and, respectively -2. They are considered extreme precipitation events that can generate flash floods or high floods, putting the tourists’ lives and tourism infrastructure under significant danger. For the ETCI score calculation, as in (4), we kept the original rating systems for W and S, as well as the weightings of all TCI sub-indices. Also, the final classification of the climate suitability for outdoor tourism (Table 2) was based on the original index presentation. E T C I = 4 × T Ed + T Ea + 2 × R + 2 × S + W

(4)

Table 2 ETCI score rating categories (modified from Mieczkowski [18]) ETCI score

Rating

Category (class)

Favorability

ETCI score

Rating

Category (class)

Favorability

90–100

9

Ideal

40–49

4

Marginal

80–89

8

Excellent

70–79

7

Very good

Suitable for outdoor tourism and recreation

Unsuitable for outdoor tourism and recreation

60–69

6

50–59

5

30–39

3

Unfavorable

20–29

2

Very unfavorable

Good

10–19

1

Extremely unfavorable

Acceptable

< 10

0

Impossible

Climate Suitability for Sustainable Economic Growth …

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where, ETCI - enhanced tourism climate index; TEd - daytime comfort index derived from daily TX and corresponding RH and W; TEa - daily comfort index calculated based on daily TG, RHA, and W; R - precipitation; S - daily sunshine hours; and W - wind speed. For further economic analysis, we retained only those 10-day periods with an average multi-annual score of at least 50 (a rate of 5), corresponding to “acceptable” or better classes of suitability for outdoor tourism and recreation. We calculated the general frequency of days in each ETCI class for the Danube Delta based on the ETCI average value for all weather stations considered.

2.2.2

Economic Analysis

The economic analysis developed in three steps: i.

ii.

iii.

First, the analysis evaluated the economic results of the tourism sector in the Danube Delta region from both static and dynamic perspectives. We analyzed the economic data by months based on climatic data detected, which indicated suitable weather conditions for outdoor tourism and recreation activities (March-November). To evaluate the economic development level, we compared the results of the Danube Delta region with the ones from the Romanian seaside of the Black Sea. This region is the principal competitor for the Danube Delta in the region, because it is located less than 150 km southward and has similar features in terms of suitable season and weather patterns. The second step consisted of a simulation of an economic increase based on tourism growth in the focus region. Since it is relatively underdeveloped from a financial perspective and one of the poorest in Romania, with inhabitants from isolated villages sometimes living in near-poverty conditions [41], we propose two scenarios for sustainable economic development based on tourism. Thus, we simulated the economic effects of two possible changes in tourists’ behavior using the available data: i. increase in the occupancy rate of the existing accommodations keeping the same number of overnight stays per tourist, and ii. growth in the number of overnight stays maintaining the same number of tourists’ arrivals. In the third step, we measured the accessibility, based on a topological network dataset, modeled in a GIS platform the fastest routes from origins (urban and rural areas) to destinations (central locations). For each road segment in the network, an average travel speed is determined to compute travel time in the origin–destination (OD) matrix (according to the type of road, road quality, weather conditions, and traffic density).

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Table 3 Characteristics of the selected ranking system in the OD matrix [59, 60] Rank

Short description

Coefficient considered for a score of zero (ak )

0

National capital city

150

1

Regional center

75

2

Sub-regional center

40

3

County seat

20

4

Important middle-sized city

12

5

Small city or town with large area of influence

8

6

Small town with minor area of influence or urban-like commune center

5

7

High-grade commune center

3

8

Commune center

2

For the Danube Delta, the accessibility index was computed using formula (5), which was successfully employed for other regions in Romania [59, 60]:

n  T rk 3− A= ak k=0

(5)

where, A - accessibility index; k - rank of the settlement; Tr k - travel time to the nearest settlement ranked k; and ak - coefficient considered for a null score (Table 3). We processed the data by using ESRI ArcGIS 10.8 platform and used the levels of accessibility determined for each location/settlement as an input point for geostatistical analysis and interpolation. After interpolation, the resulting raster dataset illustrates the spatial variability of accessibility across the region. Average values were extracted for each administrative unit.

2.2.3

Study Area

The Danube Delta is the second-largest delta in Europe after the Volga River Delta extending over approximately 6470 km2 , and about 80% belong to

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301

Romania (~5176 km2 ) and 20% to Ukraine. It is the best preserved Europe’s delta and the third largest biodiversity site globally (the largest in Europe). It is also the only river delta entirely included in UNESCO’s World Heritage Site category, as UNESCO Biosphere Reserve under the program Man and Biosphere (MAB) (since May 1991). The Danube Delta (Romanian sector) consists of a fluvial zone characterized by sandy levees and densely vegetated lakes, a transitional zone of larger lakes, reed swamps, and forested levees marine zone, dominated by dune and barrier beach complexes. The area is internationally important for breeding, staging, and wintering waterbirds. Nesting species include internationally important numbers of cormorants and pelicans. The site was formally twinned with the Camargue Ramsar site by an agreement between Romania and France, signed in 1992, as Ramsar site no. 521 [61]. The Romanian Danube Delta region covers 61% (including the Razelm Lakes System) of Tulcea county. The county’s total population is 201,000 people [41], but the great majority lives in Tulcea city and the western part of the county, not included in the Delta. Only about 10% of the county population lives in the delta region, and it consists mainly of Romanians (about 80%) and Ukrainians (about 20%), which developed an interesting mixture of culture greatly influenced by other minorities, such as Lipovans (Russians), and Turks. The inhabitants of the many scattered villages have unique cultural links with the ecosystem [61]. Developed among the three branches of the Danube and the western Black Sea coastline, consisting of numerous islands and internal lakes, the Danube Delta is home to more than 5500 species of plants and animals. With its more than 300 species, it is known as the “Birds’ Paradise.” In addition, 45 freshwater fish species [61] and many other mammals, reptiles, and insects species make it one of the most biodiverse places on this planet. The Danube Delta seems to be the perfect destination for tourists eager to practice bird watching, fishing, or enjoying wildlife and seaside vacations. The entire region is dominated by water surfaces, covering more than 85% of the total area. Not far away from the proper delta region, Histria, the ancient Greek city, or the Halmyris roman camp are other important tourist attractions. Even though there are industries and agriculture (mainly wine production), the most important economic sectors in Tulcea county are tourism and fishing. Whereas agriculture and industry dominate the economy in the western half of the county, tourism is developed almost exclusively in the Danube Delta. Especially during summer, small cities or the seaside resort of the delta (Sulina, Sf. Gheorghe or Gura Portitei) become moderately populated with tourists seeking silence away from the mainstream seaside or exploring the Danube Delta’s famous wildlife.

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3 Results 3.1 Suitable Season for Tourism Detected Based on ETCI Analysis Analysis of the ETCI calculated based on each weather station data considered for this study revealed that 24% of the days in a year correspond to excellent and ideal conditions for outdoor tourism and recreation. About the same share, 22.2%, goes to good and very good weather conditions, and more than 13% of the days recorded acceptable conditions (Fig. 2). Thus, almost 60% of days in a year are favorable for the outdoor recreation and tourism activities in the Danube Delta. We overlapped the days classified according to ETCI scores and the calendar days to detect the suitable periods for outside tourism and recreation. The inland weather stations (Tulcea and Gorgova) and Sfantu Gheorghe-Delta weather station, located on the seaside, indicated favorable conditions, getting at least “acceptable” weather from the last decade of March to the first decade of November. For the other seaside weather station (Sulina), the suitable conditions begin in April and end before the first decade of November (Fig. 3). The shorter period at Sulina may be explained by the weather station location, at the end of “bara Sulina” dam, at about 7 km inside the Black Sea. Higher wind speed over the sea (which is typical) and a delay in the warming process of the seawater and the air above it may be the causes. Under these circumstances, we shall consider

3.3% 8.7%

IDEAL

2.2%

EXCELLENT

20.5%

VERY GOOD 17.8%

GOOD ACCEPTABLE 9.6%

MARGINAL UNFAVORABLE

12.0%

VERY UNFAVORABLE 12.6%

EXTREMELY UNFAVORABLE

13.4%

Fig. 2 Frequency of suitability classes of ETCI calculated based on daily data (%)

Climate Suitability for Sustainable Economic Growth … Tulcea January_1 January_2

Gorgova

303 Sf. Gheorghe

Unfavorable

Very

January_3

unfavorable

Extremely unfavorable

Marginal

Unfavorable

February_1 February_2

Sulina Extremely unfavorable

Unfavorable

February_3 March_1 March_2 March_3 April_1

Acceptable

Marginal

April_2 April_3

Acceptable

May_1

Good

May_2 May_3

Very good

June_1 June_2 June_3 July _1 July_2

Excellent

July_3

Ideal

August_1 August_2 August_3

Excellent

September_1 September_2 September_3 October_1

Very good Good

Good

October_2 October_3

Acceptable

November_1 November_2

Marginal

November_3 December_1 December_2 December_3

Marginal Unfovorable

Very unfavorable

Fig. 3 The suitability season for outdoor tourism and recreation in the Danube Delta derived based on the ETCI

data derived from Sf. Gheorghe-Delta weather station more representative for the eastern region of the delta. From the last decade of April until the first decade of October for the inland area, and until the last decade of September for the coastal region, the conditions are at least good. The best weather/climate, classified as excellent or ideal, begins in June and lasts until the first decade of September for most of the locations considered. Ideal conditions were detected only for the seaside area, and they last for less than one month (July 21–August 10) (Fig. 3). However, the score obtained by the two decades is very close to the excellent class (less than 92).

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3.2 Economic Analysis 3.2.1

Historical Analysis

An overview analysis of the tourism sector shows the underdevelopment of the Danube Delta region. Over the considered period, in the Danube Delta, the annual revenue from tourism grew slower, at a Compound Annual Growth Rate of 9.8% between 2010 and 2018, compared with a value of 11.9% for the Romanian Black Sea seaside area, which is the most important competitor in the region nearby (Fig. 4). Thus, the Danube Delta region generates only 12–15% of the annual revenue from tourism compared to the seaside area. Moreover, the difference between the two regions consists of the available accommodation capacity. Thus, 6,078 beds were available in the Danube Delta in 2020, compared to 83,331 beds in the seaside region. A detailed analysis performed for each settlement in Tulcea county over the period 2010–2018 for the tourism turnover and number of employees indicated that the tourism sector has increased almost everywhere across the Danube Delta. However, most municipalities had low to medium growth over the considered period and either a slow annual growth rate or a weak starting point (see Table 4). There are, however, some exceptions like Baia, Carcaliu, Izvoarele, Nalbant, Stejaru, Turcoaia where both turnover and number of employees decreased over the analyzed period 2010–2018. Although the tourism turnover increased by 111% in 2018 compared with 2010, the number of employees decreased by 45%. It may be explained by the increased labor efficiency in this sector in the area. € 400 € 366 € 308

Millions

€ 300

€ 323

€ 286 € 225

€ 200 € 165

€ 172

€ 23

€ 26

€ 189

€ 194

€ 24

€ 26

€ 100

€2010

2011

2012

The Danube Delta

2013

2014

€ 27

2015

€ 35

2016

€ 35

2017

€ 39

€ 45

2018

The Romanian Black Sea seaside

Fig. 4 Annual tourism turnover in the Danube Delta vs. the Romanian Black Sea seaside region (2010–2018)

1,126,388

JIJILA

0.00

1.14

0.24

0.11

0.11

IZVOARELE

0.04

237,747

44,298

DAEN

0.38

ISACCEA

377,859

CRISAN

0.18

0.07

113,217

176,790

CIUCUROVA

110,263

68,117

CHILIA VECHE

0.12

HORIA

115,295

CERNA

0.47

GRECI

466,585

CEAMURLIA DE JOS

0.05

0.01

0.10

45,587

CARCALIU

102,486

14,011

C.A. ROSETTI

0.03

FRECATEI

27,486

BESTEPE

1.22

2.17

0.00

1,205,243

DOROBANTU

2,140,633

BAIA

11

3

1

1

7

7

5

4

2

9

2

1

12

25

0.00

0.36

0.10

0.00

0.03

0.03

0.00

0.23

0.23

0.16

0.13

0.06

0.29

0.06

0.03

0.00

0.39

0.81

111,429

239,040

1,136,981

275,200

755,465

539,772

13,691

344,516

6,909,876

312,130

599,914

174,157

937,000

216,398

343,162

1,185,960

7,405,503

RON

0.05

0.12

0.55

0.13

0.36

0.26

0.01

0.17

3.33

0.15

0.29

0.08

0.45

0.00

0.10

0.17

0.57

3.57

% of total Delta

RON

% of total Delta

No.

Tourism turnover

% of total DDa

2018 Tourism turnover

Employees

2010

BABADAG

Settelments

Table 4 Tourism activity by settlements

2

3

8

2

7

2

5

42

3

6

11

4

4

10

94

No.

0.12

0.17

0.47

0.12

0.41

0.12

0.00

0.29

2.45

0.17

0.35

0.00

0.64

0.00

0.23

0.23

0.58

5.48

% of total DD

employees

n/a

−73

−79 n/a

167

n/a

600

100

n/a

−29

500

−40

50

−100

378

143

585

427

n/a

678

1729

77

781

51

22

−100

−100 101

300

1444

n/a

−17

−2 1148

276

246

(continued)

Employees (%)

Evolution 2010–2018 Tourism turnover (%)

Climate Suitability for Sustainable Economic Growth … 305

0.90

Danube Delta

SARICHIOI

a

0.00

0.95

OSTROV

887,361

935,489

NUFARU

0.31

308,691

NALBANT

1.80

0.32

7.56

1,772,520

MALIUC

7,446,255

314,901

MAHMUDIA

0.42

MURIGHIOL

412,982

MACIN

0.00

0.85

0.00

2,425

MIHAIL KOGALNICEANU

836,727

LUNCAVITA

5

21

5

94

37

11

7

26

0.16

0.00

0.68

0.16

3.04

0.00

1.20

0.36

0.23

0.00

0.84

820,811

29,518

2,579,973

87,056

20,038,607

122,364

3,701,882

5,900,372

1,514,771

638,488

7,899,093

RON

0.40

0.01

1.24

0.04

9.65

0.06

1.78

2.84

0.73

0.31

3.80

% of total Delta

RON

% of total Delta

No.

Tourism turnover

% of total DDa

2018 Tourism turnover

Employees

2010

JURILOVCA

Settelments

Table 4 (continued)

9

1

22

1

175

4

32

64

9

7

39

No.

0.52

0.06

1.28

0.06

10.20

0.23

1.87

3.73

0.52

0.41

2.27

% of total DD

employees

−80 n/a 80

n/a −7

5

−72 176

86

n/a

−14

482

29

n/a

50

169

n/a

109

1774

267

26,229

844

Employees (%)

Evolution 2010–2018 Tourism turnover (%)

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A mixed analysis of the two databases revealed the patterns of the region. Some typical seasonality is present, especially for the Black Sea coastal region; tourism in the Danube Delta is significantly less affected with a more extended period (Fig. 5). If almost 80% of all overnight stays at the seaside happen during the summer (June– August), the same period generates only 53.4% of overnight stays in the Danube Delta. The significantly more intense activity in May and September in the Danube Delta region (23.4% of all year’s overnight stays) indicates that the local weather patterns are already well-utilized by the tourism sector. More than 40% of all accommodation structures are available across the year in the Danube Delta, and more than 70% of them are open between May and September (Fig. 6 left). When used accommodation capacity by months is considered, between 9.9% (in January) and 43% (in August) of the available places were sold, leading to the conclusion that there is no underserved demand in the region (Fig. 6 right). While specific periods and locations might get fully booked, there is sufficient over-capacity to accommodate all the demand. Thus, special measures to improve and facilitate the market are needed to increase the tourism sector. The tourists’ behavior analysis in the Danube Delta indicated that the average stay in the Delta is relatively short, 1.8 nights/tourist, with a maximum of 2.15 nights in 40.0%

40.0%

36.8% 30.4%

30.0%

30.0% 21.8%

20.0% 10.0%

17.2% 14.4% 10.3% 4.2% 1.9%2.0%2.7%

20.0% 13.1%

12.0%

10.0% 6.0% 3.9%2.6%

0.0%

3.1% 0.7%0.9%1.1%1.6%

9.0% 2.0%1.5%1.0%

0.0% Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Fig. 5 Overnight stays distributed across the year in the Danube Delta (left) vs. the Black Sea Seaside region (right)

Fig. 6 Available accommodation (left) and total occupancy (right) out of total available seats by months in the Danube Delta

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Table 5 Overnight stays per visit Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Danube Delta

1.5

1.6

1.5

1.7

1.8

2.0

2.2

2.2

1.9

1.8

1.8

1.8

Seaside

2.6

2.8

2.8

2.7

3.0

3.7

4.1

4.3

4.0

3.7

3.5

2.8

Simulationa

1.6

1.6

2.0

2.5

3.0

3.0

3.5

3.5

3.0

2.0

2.0

1.8

a

Simulation for overnight stays per visit in the Danube Delta

July and August. They represent about half of the values calculated for the seaside area (3.33 nights with a maximum of 4.28 nights in August) (Table 5). However, the value generated by each night of stay and each tourist in the Danube Delta is an important economic indicator. Each overnight stay can be translated into total revenues from tourism of an average of about 193.3 EUR (853 RON, calculated at an average exchange rate of 4.413 RON for 1 EUR) across the 2010–2018 period. The maximum value of 256 EUR was registered in 2015. The economic value of one tourist in the Danube Delta region is about 30% higher than the value of a tourist in the Black Sea seaside region. Thus, a slight increase in the Danube Delta arrivals would increase the total income more than in the seaside area.

3.2.2

Accessibility Analysis

Based on the accessibility index values, in the Danube Delta, due to the lack of ground transportation networks (roads and railways), the accessibility level is very low. The main access point in the region is Tulcea city, the main hub from a transportation perspective. Ground transportation networks (county roads, local roads) are available in the southern part of the region along the most southern Danube channel. Thus, the Danube Delta region can be considered peripheral in terms of transportation accessibility. The transport systems are provided and maintained by public authorities (SNCFR, Navrom Delta Tulcea) and private bodies, the latest operating primarily for tourism purposes. All the settlements hosting tourist accommodation infrastructures (Tulcea, Somova, Ceatalchioi, Corbu, Nuf˘aru, Mihai Bravu, Sarachioi, Cogealac, Maliuc, Mahmudia, Mila 23, Cris, an, Letea, C. A Rosetti, Lumina, Murighiol, Dunav˘at, ) are grouped in the 4th quartile of the accessibility index applied to Romania’s 16,000 local and urban settlements. From a purely economic perspective and based on tourism potential and the ease of access to various attractions, the reduced level of accessibility can be considered a restriction for tourism development in the region. In terms of environmental preservation and sustainable development, one can consider this as a positive fact. Nevertheless, the region’s infrastructure projects (like the bridge over the Danube in Braila) will enhance access in this area. This major project will not substantially modify the existing accessibility level in the remote and tourist resourcefully regions of the Danube Delta Biosphere Reservation. Recently, the President of

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309

the Management Association of the Danube Delta Tourism Destination stated that the increasing number of high speed and noisy boats used for one-day trips in the Danube Delta have a catastrophic impact on the environment and ecosystem [62].

3.2.3

Simulation and Proposals for Sustainable Economic Growth with Tourism in the Danube Delta

The economic development of an area under a protected status, such as the Danube Delta, is quite problematic: the strategy should consider increasing tourism-generated incomes and preserving the ecosystem. The traditional vacation season in Romania and Europe is summertime, with a sharp peak in July and August. For a sustainable development, the tourists’ pressure on the region should be avoided in the peak season months. Under these circumstances, we identified a few solutions to increase the income in the focus area by extension of the season: we proposed two economic development scenarios for the Danube Delta region starting from the present situation. Based on the data detailed above, we simulated the economic effects of two possible changes in tourists’ behavior: iv. v.

increase in the occupancy rate of the existing accommodation structures using the same number of overnight stays per tourist; and increase the number of overnight stays while keeping the same number of tourists’ arrivals.

Using the currently calculated ratios, we estimate 370,000 overnight arrivals in the next years, 22.5% above the value for 2019, and a total value of EUR 71.522 million (RON 315.63 million). Both simulations consider the extension of the tourism season based on the climatic results obtained before. In the first version, we simulated an increase of June–August’s occupancy rate to the “traditional seaside” values, maintained the values for November–February, and increased the April–May and September–October to 30–35%. The simulation considered the weather patterns analysis. The new accommodation occupancy rate would result in 484,835 overnight stays and EUR 93.302 million (RON 413.33 million), an increase of more than EUR 22.139 million (RON 97.7 million), representing more than 25% income above the current rate of the stays (Fig. 7). The second development scenario assumes the increase of overnight stays to the values in Table 4, which would mark an addition towards the values recorded on the seaside during the favorable season while maintaining the length of stay below 80% of the duration of stay on the Black Sea seaside during the summer months. The number of overnight stays will increase to 556,487, with a total value of EUR 107.505 million (RON 474.42 million). The estimated increase of approximately EUR 35.98 million (RON 158.78 million) represents 45.6% above the current overnight stays/trip. This second simulation would diminish the costs/room/night, mainly resulted from decreasing the cost with the general cleaning of the room, changing the towels and the bedclothes frequency, etc.

35.0%35.0%

Current stay

JAN FEB MAR APR MAY JUN

10.0% 12.0%

25.0%

30.0%

35.0% 30.0%

17.0%

12.0%

Simulation

JUL AUG SEP OCT NOV DEC

50.0%

60.0%

Fig. 7 Simulation considering the increase in the occupancy of the existing accommodations using the same number of overnight stays per tourist (values for the recent visit are the same as in Fig. 6 [right])

0.0%

20.0%

40.0%

60.0%

80.0%

310 A.-E. Croitoru et al.

Climate Suitability for Sustainable Economic Growth …

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4 Discussions To fulfill the desideratum of ensuring the sustainability of the tourism sector in a particular destination, it becomes essential to make the adaptation measures to local natural conditions more efficient [16, 17]. The interface between climate and tourism is multifaceted and complex, as climate represents both a vital resource to be exploited and an essential limiting factor that poses risks to be managed by the tourism industry and tourists alike [28, 63, 64]. Changing the tourists’ behavior toward more extended overnight stays in the Danube Delta vacation would be more environmental-friendly from the perspective of the Biosphere Reserve preservation. A longer stay would allow quiet trips on the channels using traditional engine-less boats, which would be beneficial for the Danube Delta fauna and the tourists’ satisfaction and relaxation. Thus, based on the analysis performed, a general economic growth strategy should be developed for the entire Danube Delta to extend the season and the stay. In this broad context, a diversification of the tourism types is of crucial importance. Some of them, such as educational, event, and cultural tourism, agrotourism, health/wellness tourism, are highly underdeveloped in the region and can be successfully used to fill in the “gap” in March–May and September–October/November. Some programs for specific target groups should be developed (See Table 6). They could cover a multitude of attractions, both natural and cultural, allowing nature protection of the ecosystems and the social inclusion and preservation of the cultural heritage. In a new development strategy of the region, designing and promoting tour packages for periods of 7–10 days, especially in spring and/or autumn, when the weather conditions are still suitable, should become a priority toward the region’s sustainable development. The proposed new tourism packages meet the requirement for sustainable tourism in the Danube Delta region (Table 6). They address the target tourist groups which have availability for extending their stays during spring and autumn. Those programs can increase the knowledge and awareness of the biosphere and protected areas and minority populations’ traditions (e.g., Lipovans, Ukrainians, Turks, etc.). The quiet and wild environment could serve as a perfect location for health (de-stressing) tourism, too.

5 Limitations of the Study Several issues impacted and limited the scope and result of the economic perspective of this research: i.

ii.

There is a difference between the data granularity for weather, which have a daily availability, and economic data, collected monthly and made available with delays. Several companies, some of them of considerable size, operate in the area but they have the head office outside Tulcea county (as are Green Village and Delta

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Table 6 Tourist programs for sustainable economic growth in the Danube Delta No. Program name

Tourism type

Target group

Period of the year

Stay duration

1

Seniors in the Danube Delta

All types

Retired persons

Any months

7–10 days

2

Easter with Cultural the Lipovans

All categories

April–May

Up to 1 week

3

Living with Lipovans

Cultural

All categories

Any months

Up to 1 week

4

Let’s meet the Danube Delta

Educational

Pupils/young April–May/October–November Up to people 1 week during “Different week” school program

5

Thematic Educational/sport Children summer camp for fishing, bird watching (ex. “Let’s fish sustainable”)

June–September

7–10 days

6

Sustainable hunting

Hunting season

3–7 days

iii.

Education/sport

Adults

Marina, both active in Sf. Gheorghe city, but with the head office in Bucharest). In these cases, the revenues and number of employees are not visible, as they are not included in the statistics for the Danube Delta region; the number of tourists, length of stay, etc. are however reported to the specialized agencies and captured in our analysis. The transportation system and facilities greatly influence the distribution of revenues and overnight stays at a local level because the access to the main parts of the Delta is possible only by boat, and most of the routes are covered by regular service, with just several departures per day. The “entry points” in the Danube Delta, such as Tulcea, Mahmudia, and Murghiol, with road connections, generate higher revenues and overnight stays: many tourists traveling to other destinations (Sulina, Sf. Gheorghe, Crisan, etc.) arrive late in the night and have to take a break-day before boarding the boat transportation to their final destination.

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6 Conclusions Climatic analysis revealed that favorable conditions for outdoor tourism and recreation last longer than the classical “season” for spending vacations in Romania, which usually overlaps the summer months, especially July and August. Thus, we detected acceptable conditions for a much more extended period, lasting from late March to the first decade of November. This finding is of crucial importance because there is a caveat in terms of economic development, as any proposal and effort of area development have to consider the Protected Natural Reservation status of the entire Danube Delta and tourism pressure avoidance, especially during peak season. Therefore, the benefits must be evaluated within the development’s ecological footprint, which is sometimes difficult to assess or quantify. For instance, a recent initiative, “Delta for a Day”, consists in taking the tourists from Bucharest or other big cities, speed-visits across the channels, and return to the home city on the same day. This type of program is neither suitable for sustainable tourism nor beneficial for the local population; most of the revenue is captured and remains outside the region, in the origin cities of the tourists. Moreover, the environmental experts expressed their main concern of severe disturbance of the ecosystems due to speed and noisy boats used for those one-day trips [62]. On the contrary, in this study, we proposed a set of solutions for sustainable economic development based on a scientifically-based tourism approach, which would allow both economic increase and preservation of the natural protected area. We simulated both prolongation of the season considering the climate conditions suitability (from March/April to November) and the overnight stays in the Danube Delta and an increase of 29–45% in the total amount collected resulted. As the best strategy seems to be a combined approach of the two scenarios, a set of tourism packages was proposed to sustain the tourism sector. They could be available for tourists in Romania and worldwide and can be developed by tour operators or local tourism sector stakeholders. However, campaigns for information and advertising are needed. This study could contribute to the sustainable development of tourism in the Danube Delta Biosphere Reserve by extending the tourist season based on climatic suitability, which will lead to the flattening of the arrival/overnight curve of tourists with a positive impact on the environment. As a result, the anthropogenic pressure and the ecological footprint on the ecosystem during the peak season will be reduced. Also, by dissipating the number of tourists to the edges of the season, sustainable economic growth within the tourism sector will be ensured.

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The Structural Dynamics of the Local Economy in the Danube Delta Daniel Peptenatu, Andreea Karina Gruia, Alexandra Grecu, Camelia Teodorescu, Marian Marin, Raluca Dinescu, C˘at˘alin R˘azvan Dobrea, Razvan Mihail Papuc, and Cosmin Olteanu

1 Introduction The profound changes that marked the national economies of Eastern Europe highlighted the very different adaptive capacity to the changes manifested at the level of territorial supersystems, from one local economy to another, from one geographical D. Peptenatu · C. Teodorescu · M. Marin Faculty of Geography, University of Bucharest, 010041 Bucharest, Romania e-mail: [email protected] C. Teodorescu e-mail: [email protected] M. Marin e-mail: [email protected] D. Peptenatu · A. K. Gruia · A. Grecu · C. Teodorescu · M. Marin Research Center for Integrated Analysis and Territorial Management, 030018 Bucharest, Romania A. K. Gruia (B) · A. Grecu · R. Dinescu · R. M. Papuc · C. Olteanu Faculty of Administration and Business, University of Bucharest, 030018 Bucharest, Romania e-mail: [email protected] A. Grecu e-mail: [email protected] R. Dinescu e-mail: [email protected] R. M. Papuc e-mail: [email protected] C. Olteanu e-mail: [email protected] C. R. Dobrea Faculty of Management, Bucharest University of Economic Studies, 010374 Bucharest, Romania e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_12

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region to another, registering specific structural dynamics. In the absence of an integrated strategy for the balanced development of the national territory, these development disparities have widened, currently generating major costs for economic rebalancing. The study aims at an analysis of the economic subsystem of the Danube Delta, a geographically isolated territorial system, with an economic evolution resonant with the context of the national supersystem, but with many specificities determined by geographical particularities. In the literature, research on regions with specific accessibility aims to increase the economic pressure on resources and assess the impact on affected communities. [1– 6]. These approaches are particularly important, being indispensable for the construction of territorial management systems [7–13]. The report of the Romanian Court of Accounts shows that in the period 2005–2011, at national level, the volume of illegally obtained timber was 633,500 m3 , which represents an area of approximately 292,000 ha, and in the 2003 Greenpeace report, the volume of illegally extracted timber in 2012 was about 120,000 m3 , which is 4 million euros [1, 14]. Although state institutions have tried to limit deforestation, the quantities extracted have been increasing, especially in isolated territorial systems. The direct consequence of these economic activities is the reduction of forest areas and the multiplication of negative effects, both on the natural and socio-economic environment. [1–5]. The lack of a coherent strategy for the sustainable development of the fisheries sector has meant that, on the one hand, the resources of the Danube Delta have been underutilized and, on the other hand, illegal fishing has developed. A court analysis on the performance of the management and exploitation of living aquatic resources in natural fish habitats and aquaculture in Romania, in the period 2016– 2019, highlighted the fact that the need for fish and fish products was covered, in proportion of over 80% of import. The low production was determined by illegal, unreported and unregulated fishing, by the fact that the fishing facilities in the public and private domain of the state and administered by the National Agency for Fisheries and Aquaculture were not fully concessioned. Fish exploited those located in the perimeter of the Danube Delta Biosphere Reserve in a proportion of only 57%. The Court of Accounts recommended to the Ministry of Agriculture to elaborate a Strategy for the development of the fisheries sector for the period 2021–2027, through this strategic framework the local economy could grow sustainably [15]. Due to their specificity, isolated habitats are subject to high pressure due to tourism activities, which generate increasing imbalances in ecosystems. The Danube Delta is one of the most important habitats on the continent. The characteristics of fauna and biodiversity contribute to obtaining the status of UNESCO Biosphere Reserve and RAMSAR site [16]. The promotion of its characteristics has made the economic pressure on the ecosystem to increase in recent decades, the boundaries between profitability and sustainability being more volatile, given that at European and national level many regulations have been developed to regulate the sustainable economic exploitation of these habitats. The most important strategic tool is the Strategy for the Danube Region developed in 2011 and fundamentally modified in the period 2019–2020 [17]. The need to adopt this document has resulted from outlining major challenges that cannot be addressed through national policies, the most important

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of which are: environmental threats (water pollution, floods, the effects of climate change, untapped river transport potential and lack of modern connections with other transport systems; disparities in social and economic development, lack of modern education systems). The implementation of this strategic document will contribute to the sustainable economic development of the Danube Delta, ensuring an integrated development context, by reporting to the national and European territorial supersystem, the targeted components being: modernization of the transport system, provision of cheap energy sources, environmental protection, development of the economy based on local resources, sustainable development of tourism, good governance [17]. The elaboration of norms at suprasystemic level represents an essential condition for sustainable economic development, because at national and local level there is a tendency to adapt the institutional framework to structural needs, ignoring the needs of the territorial system in its entirety. Thus, the destabilization of a component generates chain multiplication effects that affect the sustainable development of the system. The nonlinear interactions between these subsystems, strongly influenced by their specificities, determine the level of systemic integration, so any anomaly of one component will prevent the normal functioning of the others [18]. Understanding this way of functioning of the territorial reality is a condition for the elaboration of efficient territorial management strategies [19]. Understanding how isolated territorial systems work is essential for adapting structural interventions to their specificity, especially in isolated habitats, where the critical threshold of evolution can be easily reached, beyond which evolutions can be uncontrollable. An important aspect to consider in the management of isolated systems is that the local economy is based on capitalizing on local resources, which means a major structural impact on the ecosystem [20]. In these conditions, the identification of the thresholds for the economic capitalization of local resources must be clearly drawn, in the conditions of analyzes and permanent monitoring of the impact. Monitoring the impact of climate change on local resources is an essential condition for the effectiveness of economic development policies. It is well known that climate change can significantly impact these fragile habitats. Fishing is considered an extremely important activity for the local economy in the studied area, being the main engine of the functioning of the socio-economic system [21, 22], and the reduction of populations of some species would greatly affect the communities in the Danube Delta. Numerous specialized studies highlight the close link between rural development and environmental protection, the involvement of local communities being the essential condition for rehabilitation or for maintaining the balance of the ecosystem. It is well known that in communities where communities do not benefit from local resources, their attitudes towards conservation are negative [23]. Thus, the involvement of communities in the management of isolated habitats is a basic component of sustainable development strategies, involvement consisting in decentralizing resource management to local communities, the supersystem ensuring only the reporting to the sustainability thresholds of relevant indicators.

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In numerous scientific papers, community tourism is presented as a solution to rehabilitate the local economy from isolated habitats. Rediscovering elements representative of the socioeconomic life of past communities [24–31] can increase tourist attractiveness and generate positive multiplier effects in the local economy. However, this perspective exposes local economies to major systemic risks, tourism in general being an extremely volatile component, and tourism dependence in a proportion of over 25% being a major error in territorial management strategies. At the same time, the development of community tourism, within the limits of sustainability of the local economy, has an important role in the evolution of the local economy as a whole. Isolated habitats are favorable for testing development models due to the reduced systemic complexity and possibilities to quickly observe the results of territorial management policies. The tourist capitalization of the resources from these types of habitats is frequently analyzed in the specialized literature due to the immediate effects on the other components of the economic subsystem [32, 33]. The construction of territorial management strategies for isolated habitats must be based on research of all systemic components, based on advanced methodologies, as well as on a permanent monitoring of their evolution because of structural interventions. Thus, imaging analyzes can complement the classical methods of analysis, in this sense being numerous good practices [34–49].

2 Study Area Research has been conducted on the Danube Delta, the most spectacular isolated habitat in Europe. The researched area (Fig. 1) is limited to the north of Ukraine and the Dobrogea plateau’s southwest. Delta occupies a total of 5,050 km2 , of which 732 km2 belong to the state of Ukraine, Romania having an area of 2,540 km2 . The large quantities of alluvium brought by the Danube River cause the delta surface to increase annually by about 40 m2 .

3 Methodology Identifying the structural patterns of evolution of local economies involved the creation of a database with relevant indicators for the local economy, for the period 2000–2018: turnover, number of employees and number of companies. According to the Strategy for Sustainable Development of the Danube Delta [17], the main tool that traces the development directions, the administrative units located entirely or partially on the territory of the Danube Delta are: • Administrative-territorial units whose territory is entirely in the Danube Delta: Ceatalchioi, Pardina, Chilia Veche, C.A. Rosetti, Cri¸san, Maliuc, Sfântu Gheorghe and Sulina city.

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Fig. 1 Localization of administrative-territorial units from the Danube Delta (Data source ©OpenStreetMap contributors)

• Administrative-territorial units located partially on the territory of the Danube Delta: Tulcea municipality, Isaccea city, Babadag city and Murighiol, Mahmudia, Bes, tepe, Nuf˘aru, Somova, Niculit, el, Luncavit, a, Grindu, Valea Nucarilor, Sarichioi, Jurilovca, Ceamurlia de Jos, Mihai Bravu, Baia (Tulcea county) and Mihai Viteazu, Istria, S˘acele and Corbu (Constant, a county) communes. An economic database was created at the level of the administrative-territorial unit, at the level of 4-digit NACE code (Classification of National Economy Activities), grouped at the level of 2 digits (Table 1). The database highlights the main economic indicators relevant for the analysis: number of companies, turnover, and number of employees. The analysis period is between 2000 and 2018. Graphical models show the evolution of total value and weighted number of companies, turnover, and number of employees. A matrix of rank dynamics was created, in which each component is ranked according to the chosen indicator, the result being a dynamic of the position occupied by each structural element. The dynamics of the ranks show the evolution trends in the whole system, as well as at the level of each component, being an indispensable approach in assisting the decisions regarding the management of the territorial system. The matrix of rank dynamics was performed following the steps: the data were arranged, the columns representing the analyzed years, and the rows represent the NACE codes analyzed for each economic indicator. Using the RANK function, the highest value receives the digit 1, and the lowest values receive the highest digits.

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Table 1 Classification of NACE codes NACE Code

Activities

Field of activity according to NACE

01

Crop and animal production, hunting and Agriculture Forestry and Fishing related service activities

02

Forestry and logging

03

Fishing and aquaculture

5

Mining of coal and lignite

08

Other mining and quarrying

09

Mining support service activities

10

Manufacture of food products

11

Manufacture of beverages

13

Manufacture of textiles

14

Manufacture of wearing apparel

15

Manufacture of leather and related products

16

Manufacture of wood and of products of wood and cork, except furniture; manufacture of articles of straw and plaiting materials

17

Manufacture of paper and paper products

18

Printing and reproduction of recorded media

19

Manufacture of coke and refined petroleum products

20

Manufacture of chemicals and chemical products

22

Manufacture of rubber and plastic products

23

Manufacture of other non-metallic mineral products

24

Manufacture of basic metals

25

Manufacture of fabricated metal products, except machinery and equipment

26

Manufacture of computer, electronic and optical products

27

Manufacture of electrical equipment

28

Manufacture of machinery and equipment n.e.c.

29

Manufacture of motor vehicles, trailers and semi-trailers

Mining and Quarrying Manufacturing

(continued)

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Table 1 (continued) NACE Code

Activities

Field of activity according to NACE

30

Manufacture of other transport equipment

31

Manufacture of furniture

32

Other manufacturing

33

Repair and installation of machinery and equipment

35

Electricity, gas, steam and air conditioning supply

Electricity Gas Steam and Air Conditioning Supply

36

Water collection, treatment and supply

37

Sewerage

38

Waste collection, treatment and disposal activities; materials recovery

Water Supply Sewerage Waste Management and Remediation Activities

39

Remediation activities and other waste management services

41

Construction of buildings

42

Civil engineering

43

Specialised construction activities

45

Wholesale and retail trade and repair of motor vehicles and motorcycles

46

Wholesale trade, except of motor vehicles and motorcycles

47

Retail trade, except of motor vehicles and motorcycles

49

Land transport and transport via pipelines Transportation and Storage

50

Water transport

51

Air transport

52

Warehousing and support activities for transportation

53

Postal and courier activities

55

Accommodation

56

Food and beverage service activities

Accommodation and Food Service Activities

58

Publishing activities

Information and Communication

59

Motion picture, video and television programme production, sound recording and music publishing activities

60

Programming and broadcasting activities

61

Telecommunications

62

Computer programming, consultancy and related activities

Construction

Wholesale and Retail Trade; Repair of Motor Vehicles and Motorcycles

(continued)

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Table 1 (continued) NACE Code

Activities

Field of activity according to NACE

63

Information service activities

64

Financial service activities, except insurance and pension funding

66

Activities auxiliary to financial services and insurance activities

68

Real estate activities

Real Estate Activities

69

Legal and accounting activities

70

Activities of head offices; management consultancy activities

Professional Scientific and Technical Activities

71

Architectural and engineering activities; technical testing and analysis

72

Scientific research and development

73

Advertising and market research

74

Other professional, scientific and technical activities

75

Veterinary activities

77

Rental and leasing activities

78

Employment activities

79

Travel agency, tour operator and other reservation service and related activities

80

Security and investigation activities

81

Services to buildings and landscape activities

82

Office administrative, office support and other business support activities

84

Public administration and defence; compulsory social security

85

Education

Education

86

Human health activities

87

Residential care activities

Human Health and Social Work Activities

88

Social work activities without accommodation

90

Creative, arts and entertainment activities Arts Entertainment and Recreation

91

Libraries, archives, museums and other cultural activities

92

Sports activities and amusement and recreation activities

93

Activities of membership organisations

Financial and Insurance Activities

Administrative and Support Service Activities

Public Administration and Defence; Compulsory Social Security

(continued)

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325

Table 1 (continued) NACE Code

Activities

Field of activity according to NACE

94

Repair of computers and personal and household goods

Other Service Activities

95

Other personal service activities

Data source Project UB 1365

Thus, the matrix of rank dynamics for the analyzed period is constructed. The data used for the analyzes performed are part of the UB 1365 Project “Spatial projection of economic pressure on the forest ecosystem”. The values of the economic indicator turnover are expressed in the National currency unit (Romanian leu(i); 1 leu = 0.20 euro).

4 Results 4.1 The Characteristics of the Entrepreneurial Profile The evolution of the total number of companies in the administrative-territorial units whose territory is entirely in the Danube Delta (Fig. 1), shows the ascending trajectories, these being observed especially at the level of Sulina localities (with 43 companies in 2000, reaching a maximum of values in 2018, 96 companies), Cris, an (with a number of 11 companies in 2000 and registering the maximum in 2018—46 companies), Maliuc and Chilia Veche. At the opposite pole are the localities of Ceatalchioi and Pardina, which register in the analyzed period the lowest values. Evolution of the total number of companies from the administrative-territorial units whose territory is partially in the Danube Delta (Fig. 2), presents a positive trend of values. The only exception is Grindu locality (Tulcea county) which shows oscillations, from 0 companies in 2000, with a maximum of 2 companies in 2011 and 0 companies at the end of the analyzed period, 2018. The localities belonging to Constant, a county show increases in the number of companies, with slight decreases in the period 2009–2010, as a result of the economic crisis in 2008, so we have for S˘acele, a number of 10 companies in 2000, reaching 30 companies in 2018, Corbu with 17 companies in 2000 and 135 companies in 2018, Istria with a number of 5 companies in 2000 and 30 at the end of the analysis period and Mihai Viteazu with 8 companies in 2000 and 42 in 2018. The localities belonging to Tulcea county also show increases, the highest values are registered by Tulcea with 1,585 companies in 2000, reaching a number of 3,322 in 2018, Sarichioi with a number of 32 companies in 2000 and 125 in 2018, Babadag with 98 in 2000 and 171 in 2018, Somova with 35 in 2000 and 130 in 2018 and Murighiol with 22 in 2000 and 117 in 2018. Followed by Jurilovca (35 companies in 2000 and 77 companies in 2018), Mahmudia (26 companies in 2000 and 71

C. A. Rosetti (Tulcea County)

7

7

2002

2003

2004

2005

2006

2007

2008

2009

13

13

9

13

18

15

13

14

12

2018

6

2011

5

2010

5

10

3

5

10

3

2001

46

2017

80

2016

77

Linear (C. A. Rosetti (Tulcea County))

88

2015

73

96

90

87

2013

2012

2018

5

6

6

7

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

8

6

7

6

7

7

6

2017

5

2016

5

2015

4

2014

4

2013

4

2012

4

2011

4

2000

2018

18

Crișan (Tulcea County)

Maliuc (Tulcea County) Linear (Maliuc (Tulcea County))

2017

2018

14

17

17

4

3

3

2

3

3

4

2

2

3

3

2017

2018

2016

13

4

2016

2015

16

2

2015

2014

16

2

2014

2013

16

4

2013

2012

14

4

7

13

3

6

11

3

4

10

3

9

2

5

11

4

2012

2011

28

2011

2010

26

2010

2009

26

2009

2008

24

2008

2007

27

2007

2006

22

2006

2005

22

2005

2004

23

2004

2003

21

2003

2002

21

2002

2001

22

2001

2000

18

2000

18

2018

15

2017

15

19

12

2016

8

2015

7

2014

2018

46

2013

2017

45

2012

2016

48

2011

2015

50

2010

2014

43

2013

37

2012

37

2011

33

49

6

2018

2017

2015

2014

2013

2012

2011

2010

2009

2008

2007

2016

20

2017

22

2016

26

2015

2014

2013

2012

2011

2010

27

Linear (Crișan (Tulcea County))

2010

2009

28

2009

2009

2008

27

2008

2008

2005

2004

2006 2006

2005

2007 2007

27

29

26

2007

2003

2006

2002

20

24

25

2006

2001

17

23

26

2005

2000

16

2005

2003 12

24

Linear (Ceatalchioi (Tulcea County))

2004

12

22

Ceatalchioi (Tulcea County)

Linear (Chilia Veche (Tulcea County))

2003

12

19

Chilia Veche (Tulcea County)

2002

11

19

2004

18

2004

2002 19

2003

16

2002

14

2001

Linear (Sulina (Tulcea County))

2001

number of companies

100 90 80 70 60 50 40 30 20 10 0

67

86

2000

number of employees

100 90 80 70 60 50 40 30 20 10 0

63

87

Sulina (Tulcea County)

2000

number of companies

100 90 80 70 60 50 40 30 20 10 0

61

90

86

2000

43

58

81

2014

57

2000

100 90 80 70 60 50 40 30 20 10 0

D. Peptenatu et al.

2001

number of companies

326

Pardina (Tulcea County)

Sfântu Gheorghe (Tulcea County)

Linear (Pardina (Tulcea County))

Linear (Sfântu Gheorghe (Tulcea County))

Fig. 2 Evolution of the total number of companies from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018 (Data source UB/1365)

companies in 2018), Baia (34 companies in 2000 and 73 companies in 2018), Isaccea (31 companies in 2000 and 68 companies in 2018), Nuf˘aru (15 companies in 2000 and 58 companies in 2018), Valea Nucarilor (21 companies in 2000 and 57 companies in 2018), Niculit, el (14 companies in 2000 and 55 companies in 2018). Analyzing the evolution of the total number of companies by activity sectors from the administrative-territorial units whose territory is entirely and partially in the Danube Delta for 2000–2018 (Fig. 3), a detachment of the tertiary sector from the other 2 sectors analyzed can be observed. There are constant increases of values for the localities in the center of the Danube Delta and increases followed by oscillations, in the period 2009–2011 (due to the economic crisis of 2008), for the localities partially included on the territory of the Danube Delta. The primary sector registers, for the localities in the center of the Danube Delta a number of 9 companies in 2000, with a gradual increase and reaching 16 companies in 2018, and for the localities partially included on its territory the maximum number of companies is registered in 2016—439 companies, reaching 410 at the end of the analysis period. For the

The Structural Dynamics of the Local Economy in the Danube Delta Linear (Săcele (Constanța County))

Săcele (Constanța County)

240

327

Corbu (Constanța County)

Linear (Corbu (Constanța County))

130

135

2018

116

2017

99

108

2018

102

2017

2015

2016

2014

2015

110

2014

106

2013

2013

2012

91

2011

2010

2010

92

2009

90

2008

2009

80

2007

34

2006

30

2005

2004

2004

24

2003

2003

2002

18

30

2002

30

17

28

2001

25

31

14

22

31

15

18

32

14

27

11

26

10

12

26

10

2001

60 30

2000

50

64

90

2008

120

2012

180 150

2000

number of companies

210

2016

2011

2007

2006

Linear (Istria (Constanța County))

Istria (Constanța County)

240

2005

0

Mihai Viteazu (Constanța County) Linear (Mihai Viteazu (Constanța County))

180 150 120

32

36

37

37

40

40

43

42

2012

2013

2014

2015

2016

2017

2018

30

28

2011

29

30

16

21

30

16

25

8

14

23

8

2010

29

2009

29

2008

2011

33

2007

2010

30

2006

2009

28

2005

21

2004

18

2003

21

2002

17

2001

15

2008

2003

12

27

10

2007

8

2006

6

2005

7

2004

5

2002

30

2001

60

2000

90

2000

number of companies

210

Tulcea (Tulcea County)

2018

2017

2016

2015

2014

2013

2012

0

Linear ( Tulcea (Tulcea County))

Linear (Grindu (Tulcea County))

Grindu (Tulcea County)

5

4,000

4

3,000 3

2,500 2,000

2

2

2

1,500

Babadag (Tulcea County)

240

1

1

1

1

1

1

1

1

Linear (Babadag (Tulcea County))

1

2003

2004

2005

2006

0

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

0

0

0

0

2000

1

2001

1

0

2017

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

0

2018

3,322

3,531

3,573

3,626

3,655

3,738

3,688

3,810

3,394

3,496

3,679

3,334

3,055

2,789

2,477

2,237

2,005

1,733

500

1,585

1,000

1

2002

1

number of companies

number of companies

3,500

Linear (Isaccea (Tulcea County))

Isaccea (Tulcea County)

180 150

198

202

199

202

186

171

2013

2014

2015

2016

2017

2018

79

78

80

76

73

71

68

2018

193

2012

80

2017

217

2011

75

2016

201

2010

74

2015

204

2009

84

2014

204

2008

72

2013

183

2007

63

2012

170

2006

56

2011

154

2005

47

2010

138

2004

40

2003

127

2003

37

2002

116

2002

34

2001

98

104

2001

30

31

2000

90 60

2009

120

2000

number of companies

210

240

2008

2007

2006

2005

Linear (Ceamurlia de Jos (Tulcea County))

180 150 87

83

81

82

76

77

2017

2018

76

2016

81

2015

78

2014

2007

81

2013

2006

72

2012

65

2011

64

2010

62

2005

2008

56

2004

2007

49

2003

2006

35

46

2002

2005

34

39

2001

2004

37

2000

2003

45

2018

20

43

2017

18

45

2016

18

44

2015

17

41

2014

16

38

2013

14

39

2012

12

27

2009

12

2002

30

23

2001

60

2011

90

2009

120

2000

number of companies

Linear (Jurilovca (Tulcea County))

Jurilovca (Tulcea County)

Ceamurlia de Jos (Tulcea County)

210

2004

0

Linear (Mahmudia (Tulcea County))

Mahmudia (Tulcea County)

240

2008

2010

0

Mihai Bravu (Tulcea County)

Linear (Mihai Bravu (Tulcea County))

180 150 120

42

14

17

19

25

36

14

24

38

14

23

36

12

21

35

11

17

31

10

2018

71

2017

73

2016

74

2015

75

2014

80

2013

71

2012

74

2011

70

2010

62

2009

56

2008

57

2007

51

2006

46

2005

38

2004

39

2003

37

2002

35

2001

31

2001

30

26

2000

90 60

2000

number of companies

210

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

0

Fig. 3 Evolution of the total number of companies from the administrative-territorial units whose territory is partially in the Danube Delta for 2000–2018 (Data source UB/1365)

328

D. Peptenatu et al. Niculițel (Tulcea County)

240

Nufăru (Tulcea County)

Linear (Niculițel (Tulcea County))

Linear (Nufăru (Tulcea County))

180 150

50

67

66

66

65

62

64

62

58

2018

45

28

39

22

35

17

19

33

15

2017

55

2016

58

2015

63

2014

57

2013

58

2012

59

2009

51

2008

50

2007

46

2006

45

2005

2005

40

36

2004

2004

32

2003

25

2002

22

2001

21

2003

14

18

2002

30

16

2001

60

2000

90

2011

120

2000

number of companies

210

51

Somova (Tulcea County)

240

Linear (Somova (Tulcea County))

Valea Nucarilor (Tulcea County) Linear (Valea Nucarilor (Tulcea County))

210 130

135

124

128

129

120

112

55

59

62

67

66

69

64

63

57

2011

2012

2013

2014

2015

2016

2017

2018

48

2009

2003

46

2008

2002

42

2007

2001

37

50

32

2006

25

2005

25

2004

23

2000

30

21

2010

92

89

68

58

52

38

44

35

60

2001

90

55

85

120

98

150

108

180

2000

number of companies

2010

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

0

Baia (Tulcea County)

240

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

0

Luncavița (Tulcea County)

Linear (Baia (Tulcea County))

Linear (Luncavița (Tulcea County))

180 150 120 84

81

73

30 2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

0

15

17

18

19

240

30

33

36

37

34

35

37

33

Linear (Sarichioi (Tulcea County))

115

2015

2016

125

113

2014

2018

107

2013

130

111

2012

2017

105

67

55

2006

2007

51

40

2003

2005

40

2002

48

36

2001

2004

32

2000

2011

2018

108

117

2017

2010

117

95

111

2016

2009

110

2015

83

107

2014

Linear (Beștepe (Tulcea County))

Beștepe (Tulcea County)

240

83

108

2013

2010

0

2008

104

2012

85

107

2007

74

2006

2009

61

2005

74

55

64

49

2004

40

2003

28

2002

22

2001

60

36

90

2008

120

2011

150

2000

number of employees

31

Linear (Murighiol (Tulcea County))

180

30

26

Sarichioi (Tulcea County)

Murighiol (Tulcea County)

210

23

38

22

36

20

2018

79

2017

83

2016

82

2015

85

2014

80

2013

74

2012

76

2011

71

2010

65

2009

59

2008

57

2007

53

2006

52

2005

46

2004

39

2003

34

2002

60

2001

90

2000

number of employees

210

180 150 120 90

6

6

9

10

9

10

8

8

9

14

15

16

19

21

5

6

21

4

16

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

30

2001

60

2000

number of employees

210

0

Fig. 3 (continued)

secondary sector are registered values of 2 companies in 2000 and 11 in 2018 in the case of localities fully covered by the Danube Delta and a number of 287 companies in 2000 reaching 751 companies in 2018 in the case of localities partially covered by the Danube Delta. Tertiary sector—82 companies in 2000, with a slight increase and decrease in the period 2010–2011, followed by a gradual increase until 2018, 205 companies. In the localities partially included in the Danube Delta, values of 1,617 companies are registered in 2000 and 3,539 in 2018.

5

3,785

3,760

192

191

200

3,539

3,924

3,877

3,845

192

3,885

3,808

3,703

3,527

3,483 180

3,331

3,080

2,837

2,541

2,286

2,042

1,778

171

205

182

170

159

154

133

120

795

751

803

794

17 16 13 13 12 11 11

789

9

840

859

836

793

749

10 10 13 17

111

8

102

5

82

5

910

4

869

448

4

633

416

2

538

376

13 12 13 14 15 17 16 14 16 20 21 19 20 18 17 15 15 16

315

9

287

430

425

410

413

396

384

367

365

324

289

274

261

241

221

205

179

172

145

300 0

136

1,500 1,200 900 600

1,617

3,000 2,700 2,400 2,100 1,800

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

number of companies

Primary sector (partially in Danube Delta) Secondary sector (partially in Danube Delta) Tertiary sector (partially in Danube Delta)

140

Primary sector (entirely in Danube Delta) Secondary sector (entirely in Danube Delta) Tertiary sector (entirely in Danube Delta)

3,600 3,300

98

4,200 3,900

329

195

The Structural Dynamics of the Local Economy in the Danube Delta

Fig. 4 Evolution of the total number of companies by activity sectors from the administrativeterritorial units whose territory is entirely and partially in the Danube Delta for 2000–2018 (Data source UB/1365)

Analyzing the evolution of the share of the number of companies by activity sectors from the administrative-territorial units whose territory is entirely (A) and partially (B) in the Danube Delta for 2000–2018 (Fig. 4) a preponderance of the tertiary sector can be observed. The localities included entirely on the territory of the Danube Delta present a picture highlighted by the large share that the tertiary sector holds in the total of existing companies. So, we have 88.64% in 2000, there are decreases in 2009–2010 (86.89% and respectively 85.57%) followed by a gradual increase until 2018 when companies in the tertiary sector represent 88.55% of the total. At the level of the localities located partially on the territory of the Danube Delta, the tertiary sector presents values of 79.15% in 2000, oscillations in the period 2009–2010 (75.82%, 75.72%), reaching a value of the share of 75.34% of the total. The secondary sector presents a significant value for the localities located partially on the territory of the Danube Delta, with values of the share of this sector of 14.14% in 2000, increases in the post-crisis period (17.93% in 2009 and 17.21% in 2010), reaching 15.90% of the total in 2018. At the level of localities totally included in the Danube Delta, the secondary sector has the lowest shares, with 2.27% in 2000, gradual increases until 2011 and a decrease in the following period, reaching a share of 4.85% of the total in 2018. In the case of localities totally located on the territory of the Danube Delta, values of 9.09% in 2000, decreases in the post-crisis period (7.65% in 2009 and 7.96% in 2010) and a value of 6.61% of the total in 2018. At the localities partially included on its territory, registered values are 6.70% in 2000, with increases in the post-crisis period (6.25% in 2009 and 7.08% in 2010), reaching 8.76% of total in 2018.

4.2 Evolution of Turnover Analyzing the evolution of the total turnover from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018 (Fig. 5) an upward trend in total turnover can be observed. At the level of the localities that are entirely

330

D. Peptenatu et al.

a % 100.00

Primary sector

Secondary sector

Tertiary sector

88.55

87.67

86.55

86.16

84.48

83.56

85.07

83.03

85.57

86.89

85.56

84.85

86.93

86.33

70.00

86.05

86.44

85.22

80.00

88.17

88.64

90.00

60.00 50.00 40.00

6.61

4.85

6.85

5.48

7.62

5.83

8.04

5.80

8.62

6.90

8.68

7.76

10.45

4.48

9.17

7.80

7.96

6.47

7.65

5.46

8.89

5.56

10.30

4.85

9.80

3.27

10.07

3.60

10.08

3.88

10.17

3.39

11.30 3.48

2002

9.68 2.15

2001

10.00

2.27

20.00

9.09

30.00

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2000

0.00

b % 90.00

Primary sector

Secondary sector

Tertiary sector

75.34%

75.55%

75.59%

76.24%

76.43%

76.26%

75.26%

75.49%

75.82%

75.72%

76.66%

76.54%

78.81%

77.81%

60.00

79.44%

79.22%

70.00

78.70%

79.15%

79.34%

80.00

50.00

15.90% 8.76

15.87% 8.58

8.63

15.78%

15.54%

15.73% 8.23

7.50

7.84

16.24%

17.19%

17.63% 7.33

7.08

7.11

17.21%

17.93% 6.25

5.70

6.04

6.12

17.76%

17.30%

16.06%

15.01% 6.18

6.45

14.11%

14.53% 6.25

6.68

14.15% 6.51

10.00

6.70

20.00

14.14%

30.00

14.61%

40.00

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

0.00

Fig. 5 Evolution of the share of the number of companies by activity sectors from the administrative-territorial units whose territory is entirely (a) and partially (b) in the Danube Delta for 2000–2018 (Data source UB/1365)

included in the Danube Delta, the most important values of the turnover belong to the city of Sulina (48,857,230 lei in 2018) and Cris, an locality (24,529,739 lei in 2018). They are followed by Maliuc localities which register 201,044 lei in 2000 and show a gradual increase, reaching 8,269,615 lei in 2018, Sfântu Gheorghe with 157,851 lei in 2000 and 8,243,928 lei in 2018, Chilia Veche with 355,262 lei in 2000 and 6,726,903 lei in 2018 and C.A. Rosetti with 235,103 lei in 2000, reaching a value of 3,664,949 lei in 2018. The lowest values of the turnover are registered by the localities of Ceatalchioi with 136,827 lei in 2000 and 561,660 lei in 2018 and Pardina with 143,479 lei in 2000 and 227,349 lei in 2018. Evolution of the total turnover from the administrative-territorial units whose territory is partially in the Danube Delta for period 2000–2018 (Fig. 6) shows a positive trend of values. At the level of localities belonging to Constant, a county, the most important values belong to Corbu locality with 13,045,880 lei in 2000, a positive trend and a value of 99,755,482 lei in 2018, followed by S˘acele with 1,240,384 lei in 2000 and 8,749,380 lei in 2018, Istria with 426,903 lei, an increase in values and a value of 14,177,600 lei in 2018 and Mihai Viteazu with 419,430 lei in 2000 and a value of 29,090,975 lei in 2018. At the level of the localities belonging to Tulcea county, the most important ones are registered by Tulcea (with 669,685,248 lei in 2000, 5,584,200,131 lei in 2018), Babadag (with 12,266,001 lei in 2000, 239,799,994 lei in year 2018), Sarichioi (with 1,238,530 lei in 2000, 207,409,012 lei in 2018). The

3,207,475 lei

3,664,949 lei 24,529,739 lei

18,983,845 lei 8,510,632 lei

8,243,928 lei

5,132,484 lei

8,269,615 lei

2,958,214 lei

4,365,218 lei 15,101,305 lei

16,670,760 lei 8,537,367 lei

6,056,514 lei

4,224,854 lei

5,023,527 lei 6,222,009 lei

3,452,595 lei

4,409,310 lei

2,517,363 lei

3,999,251 lei

5,777,352 lei 5,908,105 lei

4,169,759 lei

7,542,798 lei

5,481,975 lei

8,231,439 lei 2,910,227 lei

3,420,994 lei

3,779,075 lei

3,204,955 lei

2,408,055 lei

2,109,353 lei

1,708,827 lei

1,036,725 lei

863,282 lei

489,833 lei

201,044 lei

768,793 lei

561,660 lei

1,080,623 lei

1,034,599 lei

746,773 lei

768,533 lei

794,839 lei

764,502 lei

756,727 lei

785,435 lei

948,861 lei

817,581 lei

660,987 lei

Linear (Maliuc (Tulcea County))

778,867 lei

Maliuc (Tulcea County)

Linear (Ceatalchioi (Tulcea County))

410,757 lei

Ceatalchioi (Tulcea County)

2,708,677 lei

7,328,708 lei

4,899,271 lei

3,702,090 lei

3,375,600 lei

2,024,608 lei

2,187,799 lei

1,423,591 lei

718,914 lei

363,859 lei

157,851 lei

227,349 lei

770,376 lei

683,893 lei

843,286 lei

713,494 lei

596,398 lei

541,577 lei

697,806 lei

430,338 lei

787,809 lei

788,487 lei

468,603 lei

445,576 lei

Linear (Sfântu Gheorghe (Tulcea County))

252,755 lei

Sfântu Gheorghe (Tulcea County)

Linear (Pardina (Tulcea County))

60,492 lei

Pardina (Tulcea County)

9,572,184 lei

2,351,490 lei

7,206,075 lei

7,887,836 lei

1,381,400 lei

6,642,438 lei

1,782,960 lei

1,362,902 lei 7,470,517 lei

7,664,942 lei

6,794,588 lei

5,179,167 lei

4,564,519 lei

6,188,093 lei

1,137,548 lei

856,934 lei

661,450 lei

417,443 lei

344,574 lei

257,526 lei

235,103 lei

48,857,230 lei

46,013,508 lei

43,445,604 lei

39,847,638 lei

29,857,725 lei

29,656,788 lei

27,539,431 lei

31,326,564 lei

31,364,499 lei

29,342,087 lei

27,307,266 lei

21,659,216 lei

17,573,349 lei

406,693 lei 4,007,558 lei

5,479,842 lei

4,759,800 lei

2,151,130 lei

2,805,463 lei

6,726,903 lei

4,905,281 lei

4,527,115 lei

4,455,913 lei

3,914,883 lei

5,473,979 lei

5,219,553 lei

4,238,794 lei

3,161,897 lei

3,235,729 lei

3,513,584 lei

2,995,701 lei

Linear (Crișan (Tulcea County))

2,379,433 lei

Crișan (Tulcea County)

Linear (Chilia Veche (Tulcea County))

1,788,589 lei

Chilia Veche (Tulcea County)

1,479,956 lei

11,159,286 lei

13,331,384 lei

Linear (C. A. Rosetti (Tulcea County))

16,265,366 lei

C. A. Rosetti (Tulcea County)

1,254,980 lei

9,319,342 lei

Sulina (Tulcea County)

244,976 lei

5,781,326 lei

331

Linear (Sulina (Tulcea County))

306,404 lei

1,030,614 lei

355,262 lei

646,209 lei 216,022 lei

124,980 lei 224,426 lei

50,000,000 lei 45,000,000 lei 40,000,000 lei 35,000,000 lei 30,000,000 lei 25,000,000 lei 20,000,000 lei 15,000,000 lei 10,000,000 lei 5,000,000 lei 0 lei

143,479 lei

50,000,000 lei 45,000,000 lei 40,000,000 lei 35,000,000 lei 30,000,000 lei 25,000,000 lei 20,000,000 lei 15,000,000 lei 10,000,000 lei 5,000,000 lei 0 lei

172,995 lei

50,000,000 lei 45,000,000 lei 40,000,000 lei 35,000,000 lei 30,000,000 lei 25,000,000 lei 20,000,000 lei 15,000,000 lei 10,000,000 lei 5,000,000 lei 0 lei

136,827 lei

50,000,000 lei 45,000,000 lei 40,000,000 lei 35,000,000 lei 30,000,000 lei 25,000,000 lei 20,000,000 lei 15,000,000 lei 10,000,000 lei 5,000,000 lei 0 lei

4,034,037 lei

The Structural Dynamics of the Local Economy in the Danube Delta

Fig. 6 Evolution of the total turnover from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018 (Data source UB/1365)

lowest values of turnover are registered by Nuf˘aru (442,863 lei in 2000, 15,922,625 lei in 2018), Bes, tepe (24,826 lei in 2000, 13,121,596 lei in 2018) and Ceamurlia de Jos (492,934 lei in 2000, 11,760,903 lei in 2018). The analysis of the turnover evolution by activity sectors from the administrativeterritorial units whose territory is entirely and partially in the Danube Delta for 2000–2018 (Fig. 7) outlines 2 different directions for the values of the 2 analyzed categories. At the level of the localities included entirely in the Danube Delta, the highest values belong to the tertiary sector which registers a value of 6,280,659 lei in 2000, shows a positive trend and a gradual increase of values, reaching 82,709,312 lei in 2018. It is followed by the primary sector which registers 1,417,867 lei registered in 2000 and an increase in turnover, reaching 15,660,727 in 2018. The secondary sector registered the lowest values with a value of 370,540 lei in 2000, reaching 2,520,878 lei at the end of the analyzed period. At the level of the localities partially included on the territory of the Danube Delta, the tertiary sector registers the most important

60,000,000 lei

30,000,000 lei

90,000,000 lei

0 lei

180,000,000 lei

20,306,390 lei

17,679,224 lei

2005

2006

2007

53,512,444 lei

48,641,014 lei

54,566,006 lei

55,626,803 lei

2013

2014

2015

2016

2017

240,000,000 lei

Mahmudia (Tulcea County)

Mihai Bravu (Tulcea County)

210,000,000 lei

Linear (Mahmudia (Tulcea County))

Linear (Mihai Bravu (Tulcea County))

2018

2017

24,171,138 lei

34,743,964 lei

27,724,686 lei

23,417,155 lei

Linear (Jurilovca (Tulcea County))

2016

Jurilovca (Tulcea County)

Linear (Ceamurlia de Jos (Tulcea County))

2015

Ceamurlia de Jos (Tulcea County)

210,000,000 lei

19,144,413 lei

240,000,000 lei 47,964,715 lei 50,745,069 lei

2016 2017

61,491,863 lei

46,974,155 lei

2015

2018

42,689,224 lei

2014

2000

2001

2002

2003

2004

2005

2006

0 lei

0 lei

0 lei

840 lei

0 lei

0 lei

16,826 lei

18,873 lei

17,492 lei

20,358,175 lei 20,768,680 lei

2016 2017

29,090,975 lei

18,540,747 lei

2015

2018

22,137,509 lei

2014

14,333,122 lei

2013

13,764,060 lei

2010

18,641,648 lei

14,827,777 lei

2009

15,515,883 lei

18,828,879 lei

2008

2012

16,991,823 lei

2007

2011

20,177,117 lei 18,721,572 lei

2006

2004 2005

17,780,393 lei

Mihai Viteazu (Constanța County)

Linear (Mihai Viteazu (Constanța County))

2014

Linear (Isaccea (Tulcea County))

40,529,985 lei

Isaccea (Tulcea County)

2013

2007

2008

0 lei

Grindu (Tulcea County)

Linear (Tulcea (Tulcea County))

90,000 lei

Linear (Grindu (Tulcea County))

80,000 lei

79,645 lei

52,540 lei

49,407 lei

4,670,360 lei

2002

10,991,089 lei

720,866 lei

2001 2003

419,430 lei

2000

14,177,600 lei

Istria (Constanța County)

Linear (Istria (Constanța County))

15,372,619 lei

Babadag (Tulcea County)

Linear (Babadag (Tulcea County))

39,197,127 lei

30,945,925 lei

21,214,976 lei

240,000,000 lei

210,000,000 lei

2012

2011

2010

2009

2010

0 lei

Tulcea (Tulcea County)

60,838 lei

48,879 lei

36,762 lei

48,751 lei

18,162,675 lei 12,846,435 lei

2018

15,384,577 lei

2015 2017

12,524,598 lei

2014 2016

11,770,022 lei

2013

29,971,310 lei

2018

99,755,482 lei

84,277,863 lei

73,641,687 lei

2016 2017

2015

95,971,521 lei

103,232,770 lei

72,324,720 lei

69,389,220 lei

2014

2013

2012

38,517,706 lei

22,010,491 lei

2010 2011

22,447,327 lei

20,304,818 lei

17,437,954 lei

2009

16,902,786 lei

2007 2008

11,387,473 lei

2006

2004 2005

19,549,305 lei

2001

17,128,144 lei

2000

12,960,902 lei

17,839,988 lei

2018

2003

13,045,880 lei

2017

2002

9,266,861 lei 8,805,310 lei 8,749,386 lei

2016

11,621,917 lei

2015

42,312,191 lei 9,014,706 lei

2014

2013

21,911,553 lei

6,319,872 lei

2011 2012

5,969,710 lei

2010

180,000,000 lei

2013

35,638,090 lei

31,833,915 lei

21,709,334 lei

2009

2011

0 lei

5,584,200,131 lei

4,461,481,855 lei

3,816,284,416 lei

4,508,541,271 lei

3,860,850,590 lei

3,810,665,134 lei

2012

36,797,507 lei

Linear (Corbu (Constanța County))

17,374,239 lei

21,859,375 lei

2012

2013

2014

2015

2016

2017

2018

2018

2017

2016

2015

2014

2013

3,582,950,157 lei

2011

2010

5,005,026 lei 4,550,615 lei

2009

150,000,000 lei

2012

2011

2010

16,151,962 lei

7,879,078 lei

2003

2008

4,975,791 lei

2002

2007

3,716,457 lei

2001

12,017,675 lei

2,898,005 lei

2000

11,140,053 lei

239,799,994 lei

2018

2006

201,158,969 lei

2017

2005

184,416,584 lei

2016

7,163,575 lei

188,821,212 lei

2015

2004

150,878,830 lei

2014

2012

3,721,000,194 lei

3,443,732,816 lei

25,511,325 lei

Corbu (Constanța County)

Linear (Săcele (Constanța County))

45,806,035 lei

49,219,978 lei

2012

2008 23,676,159 lei

25,796,733 lei

2009

21,387,612 lei

42,315,995 lei

2007

2006

31,580,385 lei

2004

2005

16,959,007 lei

4,168,851 lei

2002 12,812,283 lei

2,720,422 lei

2001

2003

2,316,174 lei

2000

133,247,115 lei

2013

2011

2010

23,006,631 lei

2009

3,433,046 lei 3,205,345 lei

2007 2008

2006

Săcele (Constanța County)

2018

45,080,382 lei

44,115,886 lei

2011

33,467,642 lei

15,093,498 lei

2004

2010

14,076,776 lei

31,058,560 lei

11,679,023 lei

2003

2009

9,014,807 lei

2002

2008

5,392,116 lei

11,760,903 lei

25,904,335 lei

2016

2018

31,690,273 lei

2015 13,799,495 lei

33,574,309 lei

2014

2017

28,456,631 lei

2013

128,817,218 lei

2012

3,428,181,686 lei

3,227,523,750 lei

4,800,000,000 lei

31,294,812 lei

2,596,015 lei

2001

104,691,872 lei

83,692,356 lei

43,974,346 lei

2000

2018

2017

2016

52,599,862 lei

2014

19,241,391 lei

2012

120,476,010 lei

2011

2009

2008

8,238,706 lei 19,283,969 lei

4,572,872 lei

2007 2008

2006

3,105,648 lei 2,040,995 lei

1,280,750 lei

2005

845,075 lei

2003 2004

2002

120,000,000 lei

2015

88,704,418 lei

88,166,532 lei

2013

74,599,644 lei

97,598,639 lei

2010

2,706,968,587 lei

2,566,031,909 lei

120,000,000 lei

2012

18,901,981 lei

2010

92,540,190 lei

2009

2007

2006

210,000,000 lei

2011

27,802,822 lei

90,422,016 lei

2008

240,000,000 lei

88,385,434 lei

26,917,622 lei

2009

89,057,598 lei

2007

2,161,125,952 lei

1,906,834 lei

1,300,729 lei

2004 2005

905,026 lei

2003

1,240,384 lei 1,004,639 lei

2001

0 lei 2000

90,000,000 lei

2011

79,311,534 lei

2009

120,000,000 lei

29,459,992 lei

16,818,272 lei

7,729,190 lei

2005

2,024,419,531 lei

586,966 lei

2002

90,000,000 lei

2008

2007

2006

72,518,134 lei

2004

1,428,777,509 lei

1,268,808,099 lei

518,887 lei

240,000,000 lei

2010

76,872,361 lei

2006

53,365,121 lei

2005

2003

2002

426,903 lei

2001

0 lei 2000

210,000,000 lei

94,409,458 lei

73,917,587 lei

62,870,026 lei

150,000,000 lei

2008

6,965,260 lei

2005

48,910,460 lei

2004

26,799,264 lei

120,000,000 lei

2003

150,000,000 lei

2007

3,751,007 lei

3,200,000,000 lei

2006

2,420,549 lei

4,000,000,000 lei

57,517,355 lei

1,342,781 lei

2004

0 lei

2003

90,000,000 lei

2002

878,788,262 lei

669,685,248 lei

5,600,000,000 lei

2005

48,637,302 lei

120,000,000 lei

43,094,146 lei

30,000,000 lei

36,846,195 lei

60,000,000 lei 2001

2000

800,000,000 lei

2004

19,137,060 lei

1,600,000,000 lei

2003

14,436,748 lei

2002

2,400,000,000 lei

2002

12,266,001 lei

2001

0 lei 2000

30,000,000 lei

531,889 lei

60,000,000 lei

492,934 lei

90,000,000 lei

2001

60,000,000 lei

2000

30,000,000 lei

33,640,638 lei

30,000,000 lei

24,753,975 lei

60,000,000 lei

2001

2000

332 D. Peptenatu et al.

270,000,000 lei

270,000,000 lei

180,000,000 lei

150,000,000 lei

6,400,000,000 lei 100,000 lei

70,000 lei 60,000 lei

50,000 lei

40,000 lei

30,000 lei

0 lei 20,000 lei

10,000 lei

0 lei

270,000,000 lei

180,000,000 lei

270,000,000 lei

180,000,000 lei

150,000,000 lei

270,000,000 lei

Fig. 7 Evolution of the total turnover from the administrative-territorial units whose territory is partially in the Danube Delta for 2000–2018 (Data source UB/1365)

87,346 lei

334,700 lei

560,488 lei

875,177 lei

2,560,060 lei

1,990,262 lei

1,802,005 lei

2,166,945 lei

2,746,406 lei

4,529,096 lei

6,192,535 lei

11,150,386 lei 13,123,986 lei 15,289,183 lei 13,121,596 lei

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

0 lei

2004

30,000,000 lei

108,787 lei

90,000,000 lei

2003

60,000,000 lei

68,757 lei

240,000,000 lei 270,000,000 lei

210,000,000 lei

120,000,000 lei

114,838,256 lei 178,996,443 lei 123,515,430 lei 126,579,139 lei 185,486,942 lei 197,768,338 lei 205,369,199 lei 207,409,012 lei

2011 2012 2013 2014 2015 2016 2017 2018

68,098,204 lei

58,453,699 lei

2009 2010

56,373,803 lei

45,755,467 lei

150,000,000 lei

2008

2007

Luncavița (Tulcea County) Linear (Luncavița (Tulcea County))

2006

12,423,845 lei

2005

142,572,264 lei

5,888,964 lei 7,091,728 lei 8,358,650 lei 9,621,415 lei

2002 2003 2004 2005

2018

2017

2016

2015

52,719,947 lei

65,306,310 lei

52,795,360 lei

44,003,910 lei

35,966,123 lei

5,766,756 lei

2003

2006

2018

2017

2016

2015

23,488,728 lei

23,924,547 lei

25,271,984 lei

24,708,793 lei

21,111,094 lei

17,963,864 lei

2013 2014

13,716,508 lei

12,533,859 lei

9,938,848 lei

9,997,976 lei

11,998,267 lei

2012

2011

2010

2009

2008

8,181,525 lei

7,147,377 lei

2007

5,767,160 lei

2005

Linear (Valea Nucarilor (Tulcea County))

2014

4,549,565 lei

2002

4,174,318 lei

3,608,878 lei

2001

2004

2,487,605 lei

2000

49,220,388 lei

2018

Valea Nucarilor (Tulcea County)

Linear (Somova (Tulcea County))

2013

162,231,470 lei

45,536,102 lei

85,273,977 lei

2017

79,360,547 lei

2016

63,448,462 lei

2015

2014

51,493,057 lei

Somova (Tulcea County)

33,197,585 lei

25,227,345 lei

19,605,425 lei

2010 2012

20,876,432 lei

2009

31,513,110 lei

19,896,598 lei

2008

2011

15,824,779 lei

2007

2006

5,486,817 lei

2001

23,088,003 lei

4,228,935 lei

2000

2018

195,985,615 lei

2017

127,438,006 lei 193,873,968 lei

2016

2015

2014

2013

39,881,643 lei

2012

2018

17,466,794 lei 15,922,625 lei

12,125,933 lei

2013

2018

10,282,321 lei

2012

14,963,846 lei

8,574,775 lei

2011

2017

7,462,929 lei

2010

2016

7,247,341 lei

2009

13,119,606 lei

6,626,926 lei

2008

12,139,641 lei

5,329,982 lei

2007

2015

3,981,286 lei

2006

2014

3,433,700 lei 3,370,514 lei

2005

1,746,935 lei

2004

2003

1,172,386 lei

29,803,499 lei

2017

848,688 lei

29,537,493 lei

2016

2002

24,262,902 lei

2015

442,863 lei

24,361,973 lei

2014

2001

21,034,780 lei

2013

2000

24,145,552 lei 19,701,863 lei

2012

12,451,461 lei

11,730,578 lei

270,000,000 lei

25,919,991 lei

9,349,040 lei

2004

21,306,022 lei

2018

6,507,252 lei

19,441,591 lei

2017

2003

18,932,452 lei

2016

4,698,586 lei

15,977,544 lei

2015

119,848,540 lei

112,836,957 lei

150,000,000 lei

2002

11,902,480 lei

2014

2013

180,000,000 lei 2011

2010

120,000,000 lei

2,647,255 lei

10,381,369 lei

2013

Linear (Baia (Tulcea County))

2012

35,741,947 lei

2011

15,794,760 lei 11,528,254 lei

9,249,865 lei

2009

2007 2008

7,105,352 lei 6,902,172 lei

2006

7,097,160 lei

2004 2005

8,597,102 lei 7,269,259 lei

2003

3,262,308 lei

Linear (Niculițel (Tulcea County))

1,238,530 lei

9,374,147 lei

2012

30,104,373 lei

2010

210,000,000 lei

135,129,162 lei

Baia (Tulcea County)

210,000,000 lei

84,630,857 lei

39,390,045 lei

30,632,456 lei

29,370,016 lei

2009

2008

2007

22,810,413 lei

30,399,569 lei

43,408,753 lei

28,521,877 lei

240,000,000 lei

2011

240,000,000 lei

2010

61,745,253 lei

150,000,000 lei

2009

2006

2005

2004

2003

1,841,790 lei

2002

2001

0 lei 2000

Niculițel (Tulcea County)

210,000,000 lei

2001

8,324,158 lei

2011

33,926,813 lei

2007 44,718,062 lei

28,306,422 lei

2006 2008

27,138,254 lei

16,367,558 lei

2005

2004

2002

11,002,515 lei 19,334,915 lei

6,892,350 lei

2002

2001

0 lei 2000

240,000,000 lei

2000

5,175,344 lei

2010

4,347,656 lei

2007 2009

4,021,681 lei

2006

240,000,000 lei

5,633,709 lei

3,389,719 lei

2005

270,000,000 lei 12,852,895 lei

6,401,705 lei

120,000,000 lei

4,725,184 lei

3,362,251 lei

2004

210,000,000 lei 2003

3,761,710 lei 3,729,988 lei

120,000,000 lei

2008

3,173,202 lei

0 lei 2003

90,000,000 lei

2002

30,000,000 lei

2002

60,000,000 lei 2001

0 lei 2000

60,000,000 lei

2,040,084 lei

30,000,000 lei

1,294,988 lei

90,000,000 lei

697,096 lei

30,000,000 lei

2001

60,000,000 lei

2000

90,000,000 lei

30,376 lei

30,000,000 lei

24,826 lei

60,000,000 lei

2001

90,000,000 lei

2000

The Structural Dynamics of the Local Economy in the Danube Delta 333

Nufăru (Tulcea County)

180,000,000 lei Linear (Nufăru (Tulcea County))

150,000,000 lei

270,000,000 lei

180,000,000 lei

270,000,000 lei

Murighiol (Tulcea County)

Linear (Murighiol (Tulcea County))

Sarichioi (Tulcea County)

180,000,000 lei Linear (Sarichioi (Tulcea County))

Linear (Beștepe (Tulcea County)) Beștepe (Tulcea County)

180,000,000 lei

120,000,000 lei 150,000,000 lei

Fig. 7 (continued)

values, with a value of 210,992,074 lei at the beginning of the analyzed period, presents a positive trend, with small post-crisis fluctuations and a gradual increase of values after this period, reaching 3,056,688,696 lei in 2018. The secondary sector is on the second position, with a value of 494,270,789 lei in 2000, with an upward trend and a value of 2,876,444,088 lei in 2018. Values much lower than these register the primary sector, with 47,788,482 lei in 2000, followed by a gradual increase in values, reaching 880,037,582 lei in 2018.

334

D. Peptenatu et al.

3,600,000,000 lei Primary sector (entirely in Danube Delta) Secondary sector (entirely in Danube Delta) Tertiary sector (entirely in Danube Delta)

3,200,000,000 lei 2,800,000,000 lei

Primary sector (partially in Danube Delta) Secondary sector (partially in Danube Delta) Tertiary sector (partially in Danube Delta)

3,056,688,696 2,876,444,088

2,400,000,000 lei 2,000,000,000 lei 1,600,000,000 lei 1,200,000,000 lei 880,037,582

800,000,000 lei

2018

2015

2017

2016

2014

2013

2011

2012

2010

2007

2006

2008

2009

2004

2005

2001

2003

2000

2018

2002

2015

2016

2017

2011

2014

2013

2012

2009

2010

2007

2006

2008

2004

2005

2003

2000

2002

2018

2001

2016

2017

2014

2015

2011

2013

2012

2008

2010

2007

2009

2005

2004

2006

2003

2001

2002

0 lei

2000

400,000,000 lei

Fig. 8 Evolution of the turnover by activity sectors from the administrative-territorial units whose territory is entirely and partially in the Danube Delta for 2000–2018 (Data source UB/1365)

The analyze of the evolution of the share of the turnover by activity sectors from the administrative-territorial units whose territory is entirely (A) and partially (B) in the Danube Delta for 2000–2018 (Fig. 8) shows significant differences between the 2 categories analyzed. For the localities included entirely in the Danube Delta, the highest share is registered by the tertiary sector with values of 77.84% in 2000, with the decrease of post-crisis values (80.48% in 2009 and 77.59% in 2010), but with a recovery of them by the end of the analysis period (82.01% in 2018). The tertiary sector is followed by the primary sector with values of the share of turnover of 17.57% in 2000, decreases in the period 2009–2010 (9.78% in 2009 and 9.49% in 2010) and an increase recorded until 2018 (15.49% of the total). The secondary sector registers the lowest share values, with 4.59% in 2000, decreases in the period 2010–2011 (12.92% in 2010 and 5.42% in 2011), the values decreasing to 2.49% of the total registered in 2018. For the localities partially included on the territory of the Danube Delta. The highest share is registered, in 2018, by the tertiary sector with values of 27.89% in 2000, increases until 2008. Additionally, it decreases after this year (49.33% in 2009 and 41.34% in 2011), reaching a share value of 44.84% in 2018. The secondary sector has the highest values at the beginning of the analyzed period (65.75% in 2000). However, the values have a downward trend (50.35% in 2010 and 48.05% in 2011), reaching 42.24% in 2018. The lowest values belong to the primary sector, with 6.36% in 2000, characterized by a positive trend, reaching a value of 12.92% of the total in 2018 (Fig. 9).

4.3 Evolution of the Number of Employees Evolution of the total number of employees from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018 shows a positive trend of values with oscillatory trajectories. Sulina registers the most important values with a number of 331 employees in 2000 and 303 employees in 2018, being followed by Chilia Veche with a number of 21 employees in 2000 and 52 employees in 2018, Cris, an with 182 employees in year 2000 and 94 employees in 2018 and Maliuc with

The Structural Dynamics of the Local Economy in the Danube Delta Primary sector

% a 90.00

Secondary sector

335

Tertiary sector

2.60

82.01

81.10

81.00

80.52 67.04

82.10

82.04

79.63

80.48

77.59

78.20

76.78

74.27

71.99

65.81

2.49

6.60

3.34

5.17

4.68

12.92

4.38

9.73

5.42

6.46

14.46

4.76

12.77

2.45

9.75

5.38

10.00

2.12

16.30

4.59

15.49

26.36

15.67

15.19

14.80

13.58

12.48

16.76 9.78

20.00

9.49

23.86

20.97

21.42

19.34

23.72

18.42

30.00

17.57

40.00

18.26

50.00

61.67

77.84

60.00

76.20

70.00

74.16

80.00

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

0.00

44.84

47.04

48.45

43.49

39.99

44.19

42.84

49.33 41.66

41.34

49.58

46.43 37.57

35.49

34.48

32.92

31.43

30.08

38.90

42.24 27.89

46.61

44.18

45.77

48.05

50.35

43.87

55.78

42.21

47.55 35.18

12.92

16.36

12.46

12.33

10.55

10.04

10.61

8.21

7.98

6.81

7.31

6.83

6.73

6.65

7.70

7.30

10.00

6.36

20.00

7.82

30.00

14.07

46.27

40.00

57.68

50.00

62.22

65.75

60.00

Tertiary sector

60.35

Secondary sector

57.71

Primary sector

% 70.00

61.27

b

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

0.00

Fig. 9 Evolution of the share of the turnover by activity sectors from the administrative-territorial units whose territory is entirely (a) and partially (b) in the Danube Delta for 2000–2018 (Data source UB/1365)

19 employees in 2000 and 72 employees in 2018. C. A. Rosetti registers 9 employees in 2000 and 24 employees in 2018 and Sfântu Gheorghe registers a number of 13 employees in 2000, with an increase of up to 36 employees in 2018. The lowest values recorded belong to the localities of Ceatalchioi with 5 employees in 2000 and 7 employees in 2018 and Pardina with 21 employees in 2000 and 2 employees in 2018. Evolution of the total number of employees from the administrative-territorial units whose territory is partially in the Danube Delta for 2000–2018 (Fig. 10) presents the oscillatory trajectories throughout the analyzed period. The localities located in Constant, a County are as follows: Corbu registers 897 employees in 2000, following a significant decrease, reaching 271 employees in 2018, Mihai Viteazu with 14 employees in 2000 and 115 employees in 2018, Istria with 19 employees in 2000 and 57 of employees in 2018 and S˘acele with 22 employees in 2000 and 52 employees in 2018. At the level of localities located in Tulcea County, the highest values are registered by Tulcea with a number of 19,395 employees in 2000, their number decreasing and reaching 18,765 employees. Bes, tepe registers the lowest values with 63 employees and Ceamurlia de Jos with 60 employees in 2018 (Fig. 11). The analyze evolution of the number of employees by activity sectors from the administrative-territorial units whose territory is entirely and partially in the Danube Delta for 2000–2018 reflects a different evolutionary picture for the 2 groups of administrative units analyzed. For localities whose territory is entirely in the Danube Delta, the total values of the number of employees are gradual increases for the

336

D. Peptenatu et al. Sulina (Tulcea County) Linear (Sulina (Tulcea County))

2018

303

24 26 28 28 26 20

292 284

2016 247 247

2014

368

2012

312

9 351

6

329

2008 346 324 338

2004

367 387

2002

364 339 331

2000 0

50

100

150

200

250

300

350

Linear (C. A. Rosetti (Tulcea County))

12 12 10 9 11 10 8 10 7 9

362

2006

C. A. Rosetti (Tulcea County)

13

385

2010

4000

50

100

150

number of employees

2018

52 51 52 59 63 59 64 71 63 52 46 42 39 35 38 33 27

2016 2014 2012 2010 2008 2006 2004 2002

0

2016

2012 2010 2008

2004 2002 2000

130

85 88

Chilia Veche (Tulcea County)

Crișan (Tulcea County)

77 77

Linear (Chilia Veche (Tulcea County))

66

Linear (Crișan (Tulcea County))

103 88 88 98 167 116 139 108 182

50

100

150

200

250

300

350

400 0

50

100

150

46 53

Linear (Pardina (Tulcea County))

2016

12 8 8 11 11 11 9 10 12 12 12 12 8 10 11 11 5

2006 2004 2002 2000 0

350

400

Sfântu Gheorghe (Tulcea County) 72

Linear (Sfântu Gheorghe (Tulcea County))

24 31 42 42 53 10 13

100

150

200

250

300

350

400 0

50

100

150

number of employees

2010

300

37

50

7 8

2008

250

59 63 62 56

Pardina (Tulcea County)

0

2012

200 number of employees

36 33 34 36

2018

2014

400

113

10 17 18 17 18 17 20 21

2006

350

107

2 4 5 6 5 5 5 5 3 5 2

2014

300

95

number of employees

2018

250

94

15 21

2000

200 number of employees

200

250

300

350

400

number of employees 72 65 49 52 71 60 49 50 53 62

Ceatalchioi (Tulcea County) Linear (Ceatalchioi (Tulcea County))

Maliuc (Tulcea County) Linear (Maliuc (Tulcea County))

71 73 60 65 60 24 16 19 19

50

100

150

200 number of employees

250

300

350

0 400

50

100

150

200

250

300

350

400

number of employees

Fig. 10 Evolution of the total number of employees from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018 (Data source UB/1365)

tertiary and secondary sectors and significant decreases for the primary sector. At the level of the tertiary sector, the values increase from 354 employees in 2000 to 495 in 2018, without notable oscillations. The secondary sector registers the lowest number of employees, 14 in 2000 reaching 35 in 2018. The primary sector registered a decrease especially after the crisis of 2008, with 138 employees in 2008 and 76 in 2009, reaching a number of 54 employees in 2018. At the level of the localities whose territory is partially on the territory of the Danube Delta located as follows: the highest values are registered by the tertiary sector, with 6,632 employees in 2000 and 11,399 in 2018, followed by the secondary sector, which registers notable decreases during the analyzed period, with 13,695 employees in 2000 and 9,667 in 2018. The

The Structural Dynamics of the Local Economy in the Danube Delta

number of employees

Corbu (Constanța County) Linear (Corbu (Constanța County))

Linear (Săcele (Constanța County)) 864

897

Săcele (Constanța County)

960

831

1,120

337

657

800

40

57

51

34

29

56

34

47

55

71

51

58

55

54

1,120

Istria (Constanța County)

number of employees

274

271

263

Mihai Viteazu (Constanța County)

Linear (Istria (Constanța County))

960

256

254

52

0

210

25

256

26

216

19

281

22

335

160

342

320

249

312

480

351

397

640

Linear (Mihai Viteazu (Constanța County))

800 640

115

103

110

97

96

92

89

73

107

122

90

89

83

66

79

122

67

22

14

60

57

50

56

50

48

183

138

136

84

52

50

41

36

30

28

19

160

18

320

131

480

0

30,000

Grindu (Tulcea County)

5

Linear (Grindu (Tulcea County))

18,765

18,597

18,608

3

19,999

20,423

20,178

20,119

20,597

20,128

21,399

24,276

24,489

24,497

23,908

22,259

22,222

19,395

17,225

15,000

24,683

4

20,000

2

2

10,000

1

1

1

1

1

1

1

1

1

1

Tulcea (Tulcea County)

5,000

number of employees

number of employees

25,000

Linear (Tulcea (Tulcea County))

0

0

0

0

0

0

0

0

0

0

0

1,280 Isaccea (Tulcea County) 1,095

975

1,015

913

311

283

366 273

227

233

224

308

236

330

304

330

300

290

225

215

180

314

462

863

1,005

814

731

Linear (Isaccea (Tulcea County))

716

855

825

613

561 451

320

537

480

721

640

773

800

900

960

518

number of employees

1,120

Babadag (Tulcea County)

160

Linear (Babadag (Tulcea County))

0

1,120

Ceamurlia de Jos (Tulcea County) 1,089

Linear (Jurilovca (Tulcea County))

1,120

177

195

183

219

233

225

223

224

217

228

179

194

179

189

173

181

152

151

141

122

221

227

214

190

300

218

401

394

390

602

605

599

452 178

100

160

579

627

572

575

527

number of employees

480 320

Linear (Mihai Bravu (Tulcea County))

Linear (Mahmudia (Tulcea County))

800 640

Mihai Bravu (Tulcea County)

Mahmudia (Tulcea County)

960

204

0

197

208

215

236

380

379

389

506 366 232

60

146

95

162

159

150

108

110

108

110

89

82

81

62

57

35

160

38

320

128

561

480

508

687

640

787

829

800

35

number of employees

Jurilovca (Tulcea County)

Linear (Ceamurlia de Jos (Tulcea County))

960

0

Fig. 11 Evolution of the total number of employees from the administrative-territorial units whose territory is partially in the Danube Delta for 2000–2018 (Data source UB/1365)

338

D. Peptenatu et al.

1,120

Linear (Nufăru (Tulcea County))

Linear (Niculițel (Tulcea County))

184

236

230 125

159 373

152

185

156

141 114

352

126 103

346

124

113 113

104

118

78

79

76

72

58

37

36

30

183

159

166

152

129

145

141

169

106

251

219

213

170

311

160

119

320

276

480

230

640

497

800

166

number of employees

Nufăru (Tulcea County)

Niculițel (Tulcea County)

960

0

Somova (Tulcea County)

Linear (Valea Nucarilor (Tulcea County))

129

126

119

141

102

90

78

54

160

48

212

273

408

393

370

303

293

218

262

335

399

223

209

198

201

320

338

480

338

640

484

800

186

number of employees

Valea Nucarilor (Tulcea County)

Linear (Somova (Tulcea County))

960

64

1,120

0

1,120

Baia (Tulcea County)

Linear (Baia (Tulcea County))

Murighiol (Tulcea County)

number of employees

960

Linear (Murighiol (Tulcea County))

800

316

320

327

303

331

322

290

288

219

215

208

193

188

225

212

141

132

145

136

320

327

291

290

283

285

263

209

237

201

209

185

168

169

147

119

160

123

320

108

480

279

640

0

Luncavița (Tulcea County)

Linear (Sarichioi (Tulcea County))

371

544

457

447

443

494

405

246

494

812 107

83

73

107

102

96

90

71

79

66

71

55

39

67

91

92

77

74

25

160

22

320

151

287

480

207

640

348

551

604

800

568

number of employees

Sarichioi (Tulcea County)

Linear (Luncavița (Tulcea County))

960

617

1,120

0

1,120

Beștepe (Tulcea County)

Linear (Beștepe (Tulcea County))

number of employees

960 800 640 480 320 160

1

0

1

2

2

4

16

6

16

17

16

20

37

30

31

96

75

73

63

0

Fig. 11 (continued)

primary sector registers the lowest number of employees, 3,211 in 2000, reaching a number of 2,149 employees in 2018. Analyzing the evolution of the share of the number of employees by activity sectors from the administrative-territorial units whose territory is entirely (A) and partially (B) in the Danube Delta for 2000–2018 (Fig. 12) there are differences between the 2 groups of administrative units analyzed. At the level of localities located with the entire territory in the Danube Delta, the situation of the share at the level of activity sectors, for the number of employees, places the tertiary sector on the first place,

The Structural Dynamics of the Local Economy in the Danube Delta

339

20,000 18,000

number of employees

16,000 14,000 12,000

Primary sector (entirely in Danube Delta) Primary sector (partially in Danube Delta) Secondary sector (entirely in Danube Delta) Secondary sector (partially in Danube Delta) Tertiary sector (entirely in Danube Delta) Tertiary sector (partially in Danube Delta)

10,000 8,000 6,000 4,000 2,000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

0

Fig. 12 Evolution of the number of employees by activity sectors from the administrative-territorial units whose territory is entirely and partially in the Danube Delta for 2000–2018 (Data source UB/1365)

detaching from the other 2 sectors, with values of 58.90% in 2000. in the post-crisis period, with 69.95% in 2008, 77.96% in 2010 and 77.99% in 2011, an increase until 2018 when a share of 84.92% of the total is registered. The primary sector follows it with shares of 38.77% in 2000, significant decreases in the post-crisis period, 12.90% in 2009 and 10.48% in 2011, the decreases continuing until the end of the analyzed period, with a value of 9.15% of the total. The secondary sector recorded the lowest values, with 2.33% in 2000, decreases in the period 2009–2011 (17.15% in 2009 and 11.53% in 2011), reaching a value of 5.93% of total in 2018. At the level of localities partially located on the territory of the Danube Delta, the highest values of the share of the number of employees, at the level of activity sectors, belong to the tertiary sector, with values of 28.05% in 2000, gradual increases and a value of 49.01% of the total in 2018. It is followed by the secondary sector which presents important values at the beginning of the analysis period, 58.28% in 2000, but which registers decreases after 2003 reaching a value of 41.71% in 2018. The primary sector registers the lowest values of the share by 13.66% in 2000, decreases in the post-crisis period, in 2009 registering 8.77%, reaching 8.91 in 2011, gradual increases until 2018, with a value of 9.28% of the total (Fig. 13).

4.4 Structural Dynamics of the Local Economy Of the 38 NACE codes, the 5 most important codes, with the most significant values of turnover in the administrative-territorial units whose territory is entirely in the Danube Delta (Table 2) are: code 47—Retail trade, except of motor vehicles and motorcycles, code 03—Fishing and aquaculture, code 55—Accommodation, code 79—Travel agency, tour operator and other reservation service and related activities and code 86—Human health activities. At the level of code 47, located on the first position of the ranking with the highest value registered in 2018, 46,871,022 lei (with a total of 2,844,218 lei in 2000), included in the field of activity Wholesale and Retail Trade; Repair of Motor Vehicles and Motorcycles, at the level of 2018, the activities are divided as follows:

340

D. Peptenatu et al.

a

Primary sector

%

Secondary sector

Tertiary sector

7.09

84.92

81.48

81.42

82.41

80.85

81.33

69.95

67.59

66.61

66.32

65.60

61.23

54.72

57.63

5.93

9.23

7.24

8.35

8.10

8.33

17.15

13.65

11.53

14.71

13.38

12.16

16.80

15.99

14.49

14.25

12.10

11.49

9.15 2.33

14.63

11.28

11.05

10.48

10.33

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

0.00

9.24

20.29

10.00

8.39

18.68

20.00

12.90

31.03

20.26

22.78

25.58

38.77

30.00

27.38

40.00

22.31

50.00

58.90

60.00

58.13

70.00

77.99

77.96

80.00

76.13

90.00

b

Primary sector

%

Secondary sector

Tertiary sector

0.00

50.21

49.09

49.01

45.73

45.45

45.16

45.35

43.33

41.75

40.45

39.52

37.09

35.16

32.81

30.76

28.91

26.43

32.73

41.71

41.18

40.12

44.90

47.19

46.10

46.02

49.46

47.77

56.69

54.48

52.09

57.56

61.95

28.05 9.73

9.28

9.67

9.37

7.66

8.91

8.63

8.45

8.79

8.77

8.42

8.39

8.15

11.15

11.04

13.66

11.91

9.63

10.00

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

20.00

11.63

30.00

50.79

40.00

58.19

50.00

55.36

58.28

60.00

59.94

70.00

Fig. 13 Evolution of the share of the number of employees by activity sectors from the administrative-territorial units whose territory is entirely (a) and partially (b) in the Danube Delta for 2000–2018 (Data source UB/1365)

code 4711—Retail sale in non-specialized stores with food, beverages or tobacco predominating amounts to a value of 40,645,792 lei, code 4723—Retail sale of fish, crustaceans and molluscs in specialized stores has a turnover value of 2,709,304 lei, code 4719—Other retail sale in non-specialized stores a value of 1,240,301 lei, code 4778 Other retail sale of new goods in specialized stores with a value of 1,237,993 lei, code 4752 Retail sale of hardware, paints and glass in specialized stores with a value of 959,520 lei, code 4751 Retail sale of textiles in specialized stores with a value of 72,157 lei and code 4773 Dispensing chemist in specialized stores with a value of 5,955 lei, the latter 2 summing up the lowest turnover values. The code 03—Fishing and aquaculture, with a value of 12,888,762 lei in 2018, included in the field of activity—Agriculture Forestry and Fishing, has as main activities: Marine fishing (code 0311) with a turnover value of 129,368 lei, Freshwater fishing (code 0312) with a value of 7,666,313 lei and Freshwater aquaculture (code 0322) with a value of 5,093,081 lei. The main activities included in the code 55—Accommodation, with a value of 1,638,486 lei in 2000 and reaching a total of 9,870,322 lei in 2018, included in the field of activity Accommodation and Food Service Activities, registered in 2018, are: Hotels and similar accommodation (code 5510) with a turnover value of 728,444 lei, Holiday and other short-stay accommodation (code 5520) with a value of 6,674,711 lei, Camping grounds, recreational vehicle parks and trailer parks (code

2000

1

3

2

10

16

8

9

5

6

16

12

4

16

16

16

16

16

16

16

7

16

NACE codes

47

03

55

79

86

50

01

56

10

38

46

52

49

36

93

61

37

41

69

68

43

15

6

15

15

15

15

15

15

15

3

10

15

15

4

7

11

15

9

5

2

1

2001

19

8

19

19

19

19

19

19

18

4

13

19

7

5

12

6

11

10

3

2

1

2002

19

10

19

19

19

19

19

19

18

4

13

19

6

7

11

16

9

8

3

2

1

2003

21

11

19

21

21

21

21

21

17

4

16

21

7

8

13

10

9

6

5

2

1

2004

21

11

14

21

21

21

21

21

15

6

16

21

4

9

18

12

8

7

5

2

1

2005

20

13

10

24

24

18

24

24

17

4

15

24

11

6

16

9

7

5

3

2

1

2006

14

12

10

21

25

15

25

25

19

4

17

25

6

9

18

11

8

5

3

2

1

2007

15

13

17

12

26

16

26

26

20

6

10

26

5

8

21

9

7

4

3

2

1

2008

3

16

18

22

26

15

26

26

19

5

9

26

7

8

20

11

10

6

4

2

1

2009

3

19

23

12

16

18

29

22

17

4

7

13

6

9

15

20

11

8

5

2

1

2010

16

22

20

10

14

21

25

13

18

3

5

9

8

6

12

24

11

7

4

2

1

2011

16

12

24

11

15

20

24

14

17

8

5

7

13

6

9

22

10

4

3

2

1

2012

13

16

24

10

15

23

25

14

17

7

6

8

11

12

3

18

9

5

2

4

1

2013

13

19

23

7

15

25

26

14

17

6

11

12

9

10

2

21

8

5

4

3

1

2014

14

26

23

11

16

22

19

13

15

6

9

10

7

8

12

18

5

4

3

2

1

2015

20

25

22

15

17

21

13

12

14

10

8

9

6

7

18

11

5

4

3

2

1

2016

21

24

20

25

17

16

13

14

15

12

9

8

7

10

11

6

5

4

3

2

1

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

2018

(continued)

2017

Table 2 Trend matrix of the 2-digit NACE codes for the turnover from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018

The Structural Dynamics of the Local Economy in the Danube Delta 341

2000

13

16

16

16

16

16

16

16

16

11

16

16

16

16

14

16

15

NACE codes

75

30

70

74

73

05

25

33

45

62

66

71

77

80

81

90

95

Table 2 (continued)

14

15

15

15

15

15

15

13

15

15

15

15

15

15

15

8

12

2001

16

17

19

19

19

19

19

15

19

19

19

19

19

19

19

9

14

2002

17

19

19

19

19

19

19

14

19

19

19

19

19

19

15

5

12

2003

18

21

15

21

21

21

21

20

21

21

21

21

21

21

14

3

12

2004

21

21

13

21

21

21

21

19

21

21

21

20

21

21

17

3

10

2005

23

24

14

24

24

24

24

21

24

24

24

22

24

24

19

8

12

2006

24

25

13

25

25

25

25

23

25

25

25

22

25

25

20

7

16

2007

23

26

14

26

25

26

26

24

26

26

26

22

26

26

19

11

18

2008

24

26

13

26

26

26

26

25

26

12

26

23

26

26

21

14

17

2009

29

29

14

29

29

29

29

26

28

10

29

24

29

29

27

25

21

2010

25

25

17

25

25

25

25

25

25

15

25

23

25

25

25

25

19

2011

24

24

18

24

24

24

24

24

24

24

24

21

24

24

23

24

19

2012

25

25

21

25

25

25

25

22

25

25

25

25

25

25

19

25

20

2013

28

28

28

28

28

27

22

28

28

28

28

28

18

24

16

28

20

2014

28

28

28

28

28

28

28

25

28

28

28

28

20

24

17

27

21

2015

28

28

28

28

28

28

28

23

28

28

28

28

26

24

16

27

19

2016

28

28

28

28

28

28

28

19

28

28

28

28

26

23

18

27

22

2017

27

27

27

27

27

27

27

27

27

27

27

27

26

25

24

23

22

2018

342 D. Peptenatu et al.

The Structural Dynamics of the Local Economy in the Danube Delta

343

5530) with 91,814 lei and Other accommodation (5590) with a turnover value of 2,375,353 lei. For code 79—Travel agency, tour operator and other reservation service and related activities, located on the fourth position, with a value of 89,861 lei in 2000 and reaching a total of 6,056,033 lei in 2018, included in the field of Administrative and Support Service Activities activity, the activities included here are represented by: Travel agency activities (7911) with a turnover value of 2,284,082 lei in 2018, Tour operator activities (7912) with a value of 3,546,602 lei and Other reservation service and related activities (7990) with a value of 225,349 lei. At the level of code 86—Human health activities, with a value of 0 lei in 2000, with an ascending evolution and reaching a total of 5,585,359 lei in 2018, included in the field of activity Human Health and Social Work Activities, activities contained here are: General medical practice activities (code 8621) with a value of 3,682,876 lei and Specialist medical practice activities (cod 8622) with a value of 1,902,483 lei, total values registered in 2018. The lowest turnover values are recorded by the codes: 77— Rental and leasing activities, 80—Security and investigation activities, 81—Services to buildings and landscape activities, 90—Creative, arts and entertainment activities and 95—Other personal service activities. The rank dynamics matrix highlights the maintenance of code 77 on the first position throughout the analyzed period. Also, the structural evolution of the local economy is given by the evolution of the rank of each economic sector. The matrix of rank dynamics by turnover highlights generally oscillating trends, because of the lack of an integrated vision on the economic development of local economies in the Danube Delta (Tables 2 and 3). At the level of the administrative-territorial units located partially on the territory of the Danube Delta (Table 3), of the 78 NACE codes, the most important 5, with the most significant values of turnover are: code 30—Manufacture of other transport equipment, code 24—Manufacture of basic metals, code 47—Retail trade, except of motor vehicles and motorcycles, code 01—Crop and animal production, hunting and related service activities and code 52—Warehousing and support activities for transportation. The most important turnover values are recorded by code 30—Manufacture of other transport equipment, with a value of 77,628,236 lei in 2000, with an ascending evolution and reaching a total of 1,251,918,486 lei in 2018, included in the field of activity manufacturing. The activities included here are Building of ships and floating structures (3011) with a value of 1,250,073,784 lei, building of pleasure and sporting boats (3012) with a value of 1,742,312 lei, Manufacture of air and spacecraft and related machinery (3030)—102,390 lei, values recorded in 2018. In the second position is the code 24—Manufacture of basic metals, with a value of 239,502,490 lei in 2000, reaching a total of 983,983,465 lei in 2018, included in the field of activity Manufacturing, the activities included here are: Aluminum production (code 2442) with a turnover value of 876,424,730 lei, Manufacture of basic iron and steel and of ferro-alloys (code 2410) with 107,177,954 lei and Casting of iron (code 2451) with a value of 380,781 lei.

2000

3

1

2

5

9

11

13

6

15

52

4

16

7

17

12

18

19

8

59

14

NACE codes

30

24

47

46

01

52

45

41

49

92

10

55

23

56

25

38

03

14

35

43

15

61

8

21

20

12

16

7

18

3

56

13

6

14

11

9

5

2

1

4

2001

15

62

8

22

21

13

17

9

19

4

58

14

6

16

11

7

5

3

1

2

2002

12

65

8

19

22

16

20

14

21

4

59

13

5

15

9

7

3

2

1

6

2003

10

43

8

20

21

14

17

16

18

5

49

11

6

15

9

7

4

2

1

3

2004

13

21

8

18

20

12

16

15

17

4

41

10

6

11

9

7

5

3

1

2

2005

12

16

9

22

21

10

18

15

14

5

33

11

7

13

8

6

4

2

1

3

2006

11

16

12

24

21

8

15

14

19

4

28

9

6

13

10

5

2

3

7

1

2007

12

17

13

23

18

7

15

16

14

4

24

8

6

10

9

5

1

2

11

3

2008

10

14

15

22

23

7

16

20

18

4

21

8

6

11

12

5

1

3

9

2

2009

11

21

16

20

14

8

23

19

17

5

18

10

7

13

9

6

2

4

3

1

2010

11

22

16

17

19

9

23

13

18

7

20

10

6

14

8

5

2

4

1

3

2011

13

19

14

24

18

9

21

10

15

8

16

11

6

12

7

5

1

4

3

2

2012

14

18

13

28

20

8

19

9

16

7

15

10

6

11

12

5

2

3

4

1

2013

15

17

13

24

19

8

21

10

14

7

16

11

6

12

9

5

1

3

4

2

2014

15

19

12

27

22

9

20

13

14

7

21

10

6

11

8

5

4

2

3

1

2015

19

17

15

16

20

9

18

13

12

8

14

11

6

10

7

2

3

1

4

5

2016

20

19

16

13

15

17

18

14

12

9

11

10

6

8

7

4

3

2

1

5

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

2018

(continued)

2017

Table 3 Trend matrix of the 2-digit NACE codes for the turnover from the administrative-territorial units whose territory is partially in the Danube Delta for 2000–2018

344 D. Peptenatu et al.

2000

25

39

10

64

21

22

23

64

64

20

54

24

35

42

64

37

46

43

53

32

40

29

NACE codes

71

86

08

36

31

50

68

39

72

42

81

02

96

64

80

95

74

22

69

85

61

70

Table 3 (continued)

48

36

33

51

40

47

34

53

39

31

24

57

17

65

65

22

28

19

65

10

35

23

2001

40

38

39

48

18

49

37

55

52

32

27

57

12

66

66

31

23

20

66

10

34

24

2002

38

39

40

42

17

51

36

45

57

33

25

60

11

69

69

30

24

18

69

10

31

23

2003

34

36

41

45

37

54

32

51

65

31

24

58

12

68

71

28

23

19

38

13

30

22

2004

40

38

48

49

39

58

37

50

62

36

27

55

22

67

72

33

25

19

26

14

34

24

2005

42

35

48

52

38

57

39

49

59

34

25

54

24

69

71

28

23

20

26

17

29

19

2006

44

31

46

51

35

55

36

49

67

34

29

52

18

68

54

26

23

22

27

17

25

20

2007

42

31

48

47

34

56

38

44

64

33

30

59

21

68

36

28

27

22

29

20

25

19

2008

38

40

48

41

37

59

36

42

51

34

30

57

13

70

33

29

27

25

24

19

28

17

2009

34

41

47

46

36

59

43

39

37

35

30

55

12

65

31

29

27

26

25

15

28

22

2010

31

39

44

47

38

52

41

46

33

34

29

50

12

64

30

32

27

26

24

15

28

21

2011

31

36

48

46

40

45

42

35

34

33

30

47

20

64

32

29

26

28

23

17

27

22

2012

36

39

48

45

40

42

41

43

38

37

30

49

23

33

31

24

27

25

21

17

26

22

2013

38

30

46

47

41

44

42

40

36

37

33

49

18

35

34

27

28

26

23

20

25

22

2014

37

38

50

47

39

42

41

36

33

34

29

43

16

31

32

24

26

28

23

17

25

18

2015

31

37

43

42

41

39

40

28

32

34

30

35

24

36

33

29

26

27

22

21

25

23

2016

30

37

42

38

40

41

39

33

36

35

28

32

31

34

29

27

25

26

23

21

22

24

42

41

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

2018

(continued)

2017

The Structural Dynamics of the Local Economy in the Danube Delta 345

2000

34

33

55

63

64

31

51

41

49

47

44

50

28

27

64

62

38

45

36

26

60

57

NACE codes

28

79

93

53

66

11

33

62

73

78

82

75

18

16

19

77

32

58

13

20

63

26

Table 3 (continued)

60

54

25

30

44

41

62

65

27

38

55

42

46

37

43

49

26

65

64

50

32

45

2001

61

56

29

30

35

45

63

66

25

41

51

43

46

44

42

50

26

66

64

53

33

36

2002

63

56

32

29

37

43

58

48

26

41

52

46

49

47

44

53

28

68

66

55

34

35

2003

67

60

52

25

39

44

62

46

26

42

53

47

48

50

40

56

35

66

64

57

29

33

2004

66

61

44

28

45

47

56

23

29

53

54

51

46

43

42

52

31

63

64

59

30

32

2005

67

62

47

37

55

53

56

41

27

50

51

46

43

44

45

40

30

61

64

60

32

31

2006

65

63

48

39

60

53

58

47

30

57

45

43

40

50

42

41

37

59

62

61

33

32

2007

67

70

43

49

53

55

54

52

32

58

50

46

35

51

45

39

26

61

62

60

37

40

2008

65

72

54

56

53

58

55

46

31

50

47

49

35

52

44

45

26

62

63

60

39

32

2009

67

72

54

49

56

60

38

48

33

44

53

52

40

58

50

32

24

62

63

64

42

51

2010

67

71

53

48

54

57

36

45

37

62

55

51

42

58

43

35

25

56

59

61

40

49

2011

65

70

52

59

54

58

38

49

41

62

55

51

39

57

44

43

25

53

56

61

37

50

2012

65

69

56

60

55

51

32

54

46

62

58

50

34

59

53

44

29

52

57

61

35

47

2013

65

66

58

59

55

60

29

53

45

61

57

48

31

54

50

43

32

51

56

62

39

52

2014

66

53

63

61

57

62

40

58

44

60

59

48

35

49

46

30

54

51

56

55

45

52

2015

63

64

60

59

57

62

45

58

48

61

54

50

46

51

53

38

52

49

55

44

47

56

2016

64

63

57

60

56

61

59

55

48

58

54

47

50

45

53

43

62

52

51

49

44

46

64

63

62

61

60

59

58

57

56

55

54

53

52

51

50

49

48

47

46

45

44

43

2018

(continued)

2017

346 D. Peptenatu et al.

2000

30

58

64

56

48

64

64

64

61

64

64

64

64

64

NACE codes

15

90

09

60

17

87

91

59

27

29

37

84

88

94

Table 3 (continued)

65

65

65

65

65

63

65

65

65

52

58

65

59

29

2001

66

66

66

66

66

65

66

66

66

54

60

47

59

28

2002

69

69

69

69

69

67

64

69

69

54

61

50

62

27

2003

71

71

71

71

71

70

63

71

71

59

61

55

69

27

2004

72

72

72

71

72

69

68

72

72

60

65

57

70

35

2005

71

71

71

71

71

70

68

71

71

63

65

58

66

36

2006

75

75

75

72

74

71

69

73

75

64

66

56

70

38

2007

74

74

74

71

74

69

65

72

74

66

63

57

73

41

2008

71

74

75

73

75

64

67

69

75

66

68

61

75

43

2009

71

72

72

72

72

57

69

70

72

66

68

61

72

45

2010

74

72

74

74

74

69

68

70

74

65

66

60

73

63

2011

73

73

73

73

73

71

67

69

73

66

68

60

72

63

2012

74

74

74

74

74

72

70

68

71

67

66

63

73

64

2013

74

74

74

74

74

71

73

64

72

69

68

67

70

63

2014

74

74

74

74

74

71

73

69

72

68

64

67

70

65

2015

74

74

74

74

74

71

73

67

72

69

66

68

70

65

2016

73

73

73

73

73

71

73

70

72

69

67

68

66

65

2017

73

73

73

73

73

73

72

71

70

69

68

67

66

65

2018

The Structural Dynamics of the Local Economy in the Danube Delta 347

348

D. Peptenatu et al.

Code 47—Retail trade, except of motor vehicles and motorcycles, included in the field of activity Wholesale and Retail Trade, Repair of Motor Vehicles And Motorcycles, totaled in 2000—89,704,705 lei, shows a positive trend reaching a value of 882,844,627 lei in 2018. There are 34 activities, with the highest values in 2018 highlighting: Retail sale in non-specialized stores with food, beverages or tobacco predominating (code 4711) with a value of 296,053,332 lei, followed by Dispensing chemist in specialized stores (4773) with a value of 208,733,127 lei, Other retail sale in non-specialized stores (4719) with 149,477,148 lei, Other retail sale of food in specialized stores (4729) with 29,821,387 lei, Retail sale of automotive fuel in specialized stores (4730) with 66,572,416 lei, Other retail sale not in stores, stalls or markets (4799) with a value of 37,608,943 lei, Retail sale of hardware, paints and glass in specialized stores (4752) with a value of 12,892,858 lei and Retail sale of sporting equipment in specialized stores (4764) with a value of 10,352,819 lei. Code 01—Crop and animal production, hunting and related service activities, located on the fourth position, with a value of 21,884,002 lei in 2000, with an ascending evolution and reaching a total of 760,047,690 lei in 2018, included in the field of activity Agriculture Forestry and Fishing, has as activities, with a significant contribution of turnover: Growing of cereals (except rice), leguminous crops and oil seeds (code 0111, with 693,994,987 lei), Mixed farming (0150, with 21,231,998 lei), Growing of grapes (code 0121, with 12,666,628 lei), Raising of dairy cattle (code 0141—9,473,756 lei), Raising of swine/pigs (code 0146—8,839,440 lei), Growing of vegetables and melons, roots and tubers (code 0113—6,424,245 lei) and Support activities for crop production (code 0161—3,869,090 lei). The lowest values are recorded by—Growing of other non-perennial crops (code 0119) with 1,413,080 lei, Growing of pome fruits and stone fruits (code 0124) with 1,170,407 lei, Raising of other animals (code 0149) with 740,365 lei, Raising of poultry (code 0147) with 144,125 lei and Raising of other cattle and buffaloes (code 0142) with 79,569 lei). Code 52—Warehousing and support activities for transportation, with a value of 14,012,364 lei in 2000, reaching a total of 224,994,823 lei in 2018, included in the field of activity Transportation and Storage includes as activities—Warehousing and storage (code 5210—166,561,007 lei), Service activities incidental to land transportation (code 5221—10,170,713 lei), Service activities incidental to water transportation (code 5222—37,782,647 lei), Service activities incidental to air transportation (code 5223—4,477,138 lei) and Other transportation support activities (code 5229—6,003,318 lei). The codes record the lowest turnover values: 29—Manufacture of motor vehicles, trailers, and semi-trailers, 37—Sewerage, 84—Public administration and defence; compulsory social security, 88—Social work activities without accommodation s, i 94—Repair of computers and personal and household goods. For the number of employees, out of the 38 NACE codes analyzed, the 5 most important codes, with the most significant values in the administrative-territorial units whose territory is entirely in the Danube Delta (Table 4), are represented by: code 47—Retail trade, except of motor vehicles and motorcycles, code 55—Accommodation, code 86—Human health activities, code 79—Travel agency, tour operator and other reservation service and related activities and code 03—Fishing and aquaculture.

2000

2

4

13

9

1

3

8

13

7

5

13

13

11

13

13

13

13

13

6

13

10

NACE codes

47

55

86

79

03

52

10

38

01

56

50

36

46

37

49

33

30

43

68

41

75

10

12

8

12

4

12

12

12

12

12

12

6

7

12

11

3

2

8

12

5

1

2001

13

14

9

14

4

14

14

14

14

14

12

5

8

14

7

3

2

10

11

6

1

2002

12

15

10

15

4

15

13

15

15

15

15

8

7

15

6

3

2

9

11

5

1

2003

27

22

18

23

3

18

19

20

25

19

20

3

9

21

8

2

1

2

25

4

2

2004

12

20

11

20

3

20

12

20

12

20

12

10

8

20

7

4

2

5

9

6

1

2005

15

20

11

15

3

20

20

20

15

20

15

7

8

20

10

4

2

5

9

6

1

2006

19

13

12

15

3

21

15

21

21

21

10

8

9

21

7

4

2

5

10

5

1

2007

18

11

13

15

5

22

13

22

12

22

8

10

18

22

7

3

2

6

9

4

1

2008

20

13

16

9

10

6

14

23

14

23

12

8

16

23

7

4

2

5

10

3

1

2009

22

22

15

10

15

7

15

14

15

13

12

9

15

8

6

2

3

5

10

4

1

2010

20

12

22

15

17

10

16

11

14

12

22

7

17

8

6

2

3

4

9

5

1

2011

20

12

20

14

18

23

15

11

13

10

16

8

18

6

7

4

2

5

9

3

1

2012

20

15

19

11

20

24

15

12

14

10

15

8

13

6

6

2

3

5

9

4

1

2013

20

14

16

13

20

20

17

12

15

11

18

6

10

8

6

5

2

3

8

4

1

2014

21

22

17

13

18

14

14

11

12

10

14

7

18

9

5

6

3

3

8

2

1

2015

22

17

17

15

17

13

15

13

11

10

12

8

17

7

6

8

3

4

5

2

1

2016

18

20

20

16

18

14

16

14

11

11

10

9

13

8

7

6

3

4

5

2

1

20

20

17

17

17

16

15

14

12

12

11

9

9

7

7

6

5

4

3

2

1

2018

(continued)

2017

Table 4 Trend matrix of the 2-digit NACE codes for the number of employees from the administrative-territorial units whose territory is entirely in the Danube Delta for 2000–2018

The Structural Dynamics of the Local Economy in the Danube Delta 349

2000

13

13

13

13

13

13

13

13

13

13

13

13

13

13

11

13

13

NACE codes

93

61

74

05

25

45

62

66

69

70

71

73

77

80

81

90

95

Table 4 (continued)

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

12

2001

14

14

14

14

14

14

14

14

14

14

14

14

14

14

14

14

14

2002

14

15

15

15

15

15

15

15

15

15

15

15

15

15

15

15

15

2003

35

35

32

34

33

31

30

26

29

28

27

24

17

16

32

26

36

2004

12

20

12

20

20

20

20

12

12

20

20

20

20

20

20

20

20

2005

20

20

12

20

20

20

20

15

12

20

20

20

20

20

20

12

20

2006

21

21

15

21

21

21

21

19

15

21

21

21

21

21

21

13

21

2007

22

22

15

22

22

22

22

18

18

22

22

22

22

22

22

15

22

2008

23

23

18

23

23

23

23

20

20

23

23

23

23

23

23

18

23

2009

26

26

20

26

26

26

26

26

22

26

26

22

26

26

26

20

26

2010

25

25

20

25

25

25

25

25

22

25

25

25

25

25

25

17

25

2011

23

23

16

23

23

23

23

23

23

23

23

23

23

23

23

20

23

2012

24

24

20

24

24

24

24

18

24

20

24

24

24

24

24

24

24

2013

25

25

25

25

25

25

20

19

25

20

25

25

25

25

25

25

25

2014

22

22

22

22

22

22

22

18

22

22

22

22

22

22

22

22

22

2015

24

24

24

24

24

24

24

24

24

24

22

24

24

24

24

24

21

2016

23

23

23

23

23

23

23

23

23

23

22

23

23

23

23

23

23

2017

25

25

25

25

25

25

25

25

25

25

25

25

25

25

23

23

20

2018

350 D. Peptenatu et al.

The Structural Dynamics of the Local Economy in the Danube Delta

351

Code 47—Retail trade, except of motor vehicles and motorcycles, Wholesale and Retail Trade; Repair of Motor Vehicles and Motorcycles, presents as main activities: 4711 (Retail sale in non-specialized stores with food, beverages or tobacco predominating—174 employees), 4719 (Other retail sale in non-specialized stores—9 employees), 4723 (Retail sale of fish, crustaceans and molluscs in specialized stores—6 employees), 4751 (Retail sale of textiles in specialized stores—2 employees), 4752 (Retail sale of hardware, paints and glass in specialized stores— 3 employees) and 4778 (Other retail sale of new goods in specialized stores—10 employees). On the second position is the code 55—Accommodation, Accommodation and Food Service Activities, has as main activities: 5510—Hotels and similar accommodation with a number of 8 employees, 5520—Holiday and other short-stay accommodation with 58 employees, 5530—Camping grounds, recreational vehicle parks and trailer parks with 2 employees and 5590—Other accommodation with 16 employees. At the level of code 86—Human health activities, with a number of 0 employees in 2000, reaching a total of 45 employees in 2018, included in the field of activity Human Health and Social Work Activities are highlighted the activities: 8621 (General medical practice activities—31 employees) and 8622 (Specialist medical practice activities—14 employees). Code 79—Travel agency, tour operator and other reservation service and related activities, found on the fourth position, with a number of 13 employees in 2000, reaching a total of 43 employees in 2018, included in the field of activity Administrative and Support Service Activities, has as main activities: Travel agency activities (7911) with a number of 10 employees, Tour operator activities (7912) with 30 employees and Other reservation service and related activities (7990) with 3 employees. Code 03—Fishing and aquaculture, with a number of 214 employees in 2000, but with a negative trend, reaching a total of 33 employees in 2018, included in the field of activity Agriculture Forestry and Fishing, has as activities—0312—Freshwater fishing (with a number of 7 employees) and 0322—Freshwater aquaculture (with a number of 26 employees). The codes record the lowest values: 77—Rental and leasing activities, 80—Security and investigation activities, 81—Services to buildings and landscape activities, 90—Creative, arts and entertainment activities and 95—Other personal service activities. The matrix of rank dynamics by the number of employees shows the same oscillating evolution, resulting from the lack of coherence in the integrated development of the local economy (Tables 4 and 5). At the level of the administrative-territorial units located partially on the territory of the Danube Delta, the most significant values of the number of employees (Table 5) are registered by the codes: 30—Manufacture of other transport equipment, 47—Retail trade, except of motor vehicles and motorcycles, 01—Crop and animal production, hunting and related service activities, 46—Wholesale trade, except of motor vehicles and motorcycles and 41—Construction of buildings.

2000

2

3

7

10

5

1

15

17

6

4

14

16

12

18

62

56

13

26

30

19

35

NACE codes

30

47

01

46

41

14

49

56

10

24

55

25

43

45

36

81

52

38

71

96

86

33

20

30

29

12

55

61

17

11

18

13

5

4

16

14

3

6

9

8

1

2

2001

34

19

29

29

15

54

65

21

11

18

16

4

5

17

14

1

6

10

7

2

3

2002

30

21

29

28

15

59

67

23

11

16

17

7

5

18

12

1

4

10

6

2

3

2003

30

22

28

29

15

58

24

20

10

14

16

3

6

17

13

1

5

8

7

2

4

2004

31

21

29

30

16

55

26

22

11

10

14

4

5

15

12

1

6

8

7

2

3

2005

29

20

25

31

15

51

26

19

11

9

14

5

4

13

10

2

6

7

8

1

3

2006

26

18

21

31

15

47

24

19

10

6

12

8

5

14

11

3

4

9

7

2

1

2007

24

19

20

30

17

44

23

18

9

4

12

11

5

13

10

6

3

7

8

1

2

2008

24

19

17

33

21

40

22

16

11

4

12

9

3

13

10

6

5

7

8

1

2

2009

24

19

15

31

16

40

18

17

11

6

13

8

3

12

10

5

4

9

7

1

2

2010

22

21

20

27

14

38

19

16

11

8

13

7

5

12

10

6

3

9

4

1

2

2011

22

21

20

25

14

34

16

15

13

6

12

10

7

11

9

5

3

8

4

1

2

2012

21

18

19

27

15

33

16

14

13

7

12

9

6

11

10

5

4

8

3

2

1

2013

24

19

17

25

18

35

15

13

14

7

11

9

5

12

10

3

6

8

3

2

1

2014

21

18

17

26

19

28

14

13

16

6

11

9

8

12

10

4

5

7

3

2

1

2015

22

19

20

28

18

21

15

13

14

6

12

10

7

11

9

8

4

5

3

1

2

2016

20

19

21

23

18

16

14

15

13

9

11

10

7

12

8

5

4

6

3

2

1

21

19

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

2018

(continued)

2017

Table 5 Trend matrix of the 2-digit NACE codes for the number of employees from the administrative-territorial units whose territory is partially in the Danube Delta for 2000–2018

352 D. Peptenatu et al.

2000

11

9

20

62

54

22

62

24

34

21

62

25

51

8

47

56

40

28

62

33

36

NACE codes

23

03

31

80

35

50

39

02

85

42

72

68

69

08

70

92

74

79

53

95

22

Table 5 (continued)

38

35

61

32

49

61

45

7

52

27

61

21

36

24

61

22

60

34

19

15

10

2001

23

35

65

33

53

60

51

8

54

31

65

9

36

26

65

25

61

37

20

12

13

2002

26

39

63

32

49

58

47

14

48

30

67

8

37

22

67

27

57

36

19

9

13

2003

42

37

66

31

53

62

43

12

45

32

69

11

38

23

71

26

55

35

19

9

18

2004

42

37

67

32

56

59

42

13

42

33

68

18

39

20

72

25

34

24

19

9

17

2005

40

36

66

33

57

56

48

12

44

27

68

23

37

21

72

24

32

30

18

16

17

2006

41

38

66

34

58

55

50

13

44

28

70

22

39

25

30

23

33

29

20

16

17

2007

37

35

63

34

50

54

41

14

43

29

70

25

38

22

32

27

33

26

21

15

16

2008

38

37

62

34

53

49

36

14

39

30

73

27

35

20

32

28

29

26

23

15

25

2009

44

38

63

34

52

51

35

21

39

31

65

26

35

20

29

27

30

25

23

14

22

2010

41

41

58

32

47

43

35

25

44

31

63

17

37

23

30

28

29

24

26

15

18

2011

41

38

57

36

46

44

32

23

40

30

68

18

37

27

30

28

29

17

26

19

24

2012

46

43

58

39

43

37

36

31

42

22

34

25

35

23

32

30

29

24

26

17

20

2013

51

44

56

43

42

38

40

36

46

23

32

26

34

27

31

30

27

16

22

21

20

2014

47

45

54

43

38

40

37

35

44

31

32

24

34

27

30

29

25

15

22

23

20

2015

47

45

48

44

36

37

35

34

42

32

17

26

33

29

31

30

27

16

25

23

24

2016

45

41

48

41

37

40

34

36

35

33

27

30

32

28

31

29

26

17

25

22

23

42

40

40

38

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

2018

(continued)

2017

The Structural Dynamics of the Local Economy in the Danube Delta 353

2000

23

59

47

46

62

42

38

31

40

39

47

29

53

61

37

42

50

62

32

62

45

NACE codes

16

93

28

33

66

82

75

32

18

64

78

11

73

77

61

20

62

19

13

09

58

Table 5 (continued)

46

61

25

61

50

43

40

61

53

28

55

39

41

31

42

43

61

46

51

54

23

2001

41

65

27

61

48

45

39

61

46

28

51

50

40

32

42

43

65

48

38

59

24

2002

35

51

25

67

45

40

41

63

54

33

50

59

42

34

44

46

67

54

38

54

24

2003

39

54

27

59

48

51

40

64

52

33

50

41

47

35

45

48

64

56

34

56

25

2004

49

56

27

61

42

53

40

64

52

36

47

41

46

38

50

51

65

53

35

58

28

2005

53

59

46

58

49

46

38

63

55

35

44

42

54

39

50

41

61

43

34

61

27

2006

57

59

56

63

46

52

37

53

53

40

48

45

51

42

49

43

64

35

36

60

32

2007

53

59

56

60

46

52

36

55

51

40

48

61

58

45

42

47

56

39

49

62

31

2008

60

59

54

61

43

51

43

56

58

41

42

48

68

46

46

45

56

50

52

54

31

2009

56

57

52

58

37

52

48

41

58

43

41

45

62

50

47

46

58

49

55

61

33

2010

57

59

50

61

36

53

47

53

59

34

40

52

64

46

49

45

53

39

51

56

33

2011

52

59

61

60

39

54

49

50

54

33

42

50

61

48

47

43

52

45

58

56

35

2012

50

61

64

59

45

57

53

49

59

40

28

41

62

46

54

48

55

51

51

55

37

2013

57

62

65

60

45

59

58

50

60

41

29

37

63

48

53

47

54

49

52

55

39

2014

53

66

63

62

42

61

50

33

60

59

36

39

56

46

58

49

51

48

56

51

41

2015

50

64

63

61

43

60

51

41

55

58

39

38

58

56

52

52

48

46

57

54

40

2016

60

64

63

61

38

58

54

58

56

62

52

55

57

44

52

51

49

45

50

47

43

62

62

61

60

58

58

57

56

54

54

53

52

51

50

49

48

46

46

45

43

43

2018

(continued)

2017

354 D. Peptenatu et al.

2000

56

51

44

54

62

62

62

62

26

59

62

62

62

62

62

NACE codes

63

26

17

60

59

90

91

87

15

27

29

37

84

88

94

Table 5 (continued)

61

61

61

61

61

61

26

61

61

55

61

58

46

58

37

2001

65

65

65

65

65

61

22

65

65

58

65

56

47

57

44

2002

67

67

67

67

67

63

20

67

67

62

63

52

52

61

43

2003

71

71

71

71

71

69

20

71

71

66

68

59

59

63

44

2004

72

72

72

71

72

68

23

72

72

65

68

61

60

63

48

2005

72

72

72

70

72

68

22

72

72

70

67

64

60

65

52

2006

73

73

73

71

73

69

27

73

71

73

68

60

65

67

60

2007

73

73

73

70

73

69

28

73

72

73

65

64

65

68

67

2008

69

73

73

69

73

67

18

73

69

73

63

65

64

66

69

2009

71

69

73

73

73

67

28

73

71

73

69

65

64

67

73

2010

72

69

72

72

72

67

65

72

69

72

69

67

62

66

72

2011

73

73

73

73

73

68

64

73

64

71

70

66

61

66

71

2012

74

74

74

74

74

69

67

69

65

72

72

65

62

67

69

2013

74

74

74

74

74

68

33

71

66

71

71

70

63

67

68

2014

73

73

73

73

73

69

55

71

70

71

73

68

67

64

64

2015

73

73

73

73

73

68

69

72

71

70

73

67

65

65

62

2016

74

74

74

74

74

68

39

72

71

69

72

69

66

66

64

2017

72

72

72

72

72

72

72

71

68

68

68

66

66

65

64

2018

The Structural Dynamics of the Local Economy in the Danube Delta 355

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D. Peptenatu et al.

Code 30—Manufacture of other transport equipment, with a number of 3,229 employees in 2000, reaching a total of 3,995 employees in 2018, included in the field of activity Manufacturing, presents as main activities in which employees are concentrated (at the level of 4-digit NACE code): Building of ships and floating structures—code 3011 (with 3,985 employees), Building of pleasure and sporting boats—code 3012 (with 9 employees) and Manufacture of air and spacecraft and related machinery—code 3030 (with 1 employee). At the level of code 47—Retail trade, except for motor vehicles and motorcycles, with a number of 2,730 employees in 2000, reaching a total of 3,236 employees in 2018, included in the field of activity Wholesale and Retail Trade; Repair of Motor Vehicles and Motorcycles, economic activities with a large number of employees are: 4711—Retail sale in non-specialized stores with food, beverages or tobacco predominating (1,360 employees), 4773—Dispensing chemist in specialized stores (630 employees), 4719—Other retail sale in non-specialized stores (524 employees), 4730—Retail sale of automotive fuel in specialized stores (129 employees) and 4729—Other retail sale of food in specialized stores (108 employees). Code 01—Crop and animal production, hunting and related service activities, with a number of 1,197 employees in 2000, totaling a number of 1,702 employees in 2018, included in the field of activity Agriculture Forestry and Fishing, has as main activities, with a significant number of employees: 0111 (Growing of cereals (except rice), leguminous crops and oil seeds—1,360 employees), 0121 (Growing of grapes—96 employees), 0146 (Raising of swine/pigs—82 employees), 0141 (Raising of dairy cattle—45 employees), 0150 (Mixed farming—45 employees), 0113 (Growing of vegetables and melons, roots and tubers—29 employees) and 0161 (Support activities for crop production—24 employees). The lowest values are recorded by: 0124 (Growing of pome fruits and stone fruits—11 employees), 0119 (Growing of other non-perennial crops -6 employees), 0142 (Raising of other cattle and buffaloes—2 employees) s, i 0149 (Raising of other animals—2 employees). With a number of 608 employees in 2000, totaling 1,162 employees in 2018, code 46—Wholesale trade, except of motor vehicles and motorcycles, included in the field of activity Wholesale and Retail Trade; Repair of Motor Vehicles and Motorcycles, includes as main activities: 4632 (Wholesale of meat and meat products—165 employees), 4639 (Non-specialized wholesale of food, beverages and tobacco— 172 employees), 4673 (Wholesale of wood, construction materials and sanitary equipment—140 employees), 4674 (Wholesale of hardware, plumbing and heating equipment and supplies—101 employees) and 4690 (Non-specialized wholesale trade—237 employees). Code 41—Construction of buildings, with a number of 1,427 employees in 2000, reaching a total of 1,034 employees in 2018, included in the field of activity Construction, includes as activities: 4110—Development of building projects—58 employees and 4120—Construction of residential and non-residential buildings— 976 employees.

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5 Conclusions The analysis of the indicators relevant for the local economy in the study area highlighted the particular response of this geographical area to the context given by the national economy and the policies specific to the researched area. The twoway research approach (territorial administrative units located entirely and partially in the Danube Delta) highlighted the role of geographical isolation in the evolution of economic indicators, as well as the complexity of the local economies with different dynamics, clearly superior to the administrative units that have the partial administrative territory in the Danube Delta. Thus, the development of the local economy is dependent on the development of modern road axes, which would link the main development pole Tulcea to the Sulina s, i Chilia Veche, thus, the premises for transforming the two localities into growth centers indispensable for a sustainable economic development would be created. Also, the modernization of the TulceaDunav˘at, ul de Jos Road axis and the connection to the national and European road corridors, will contribute to attracting investments indispensable for the sustainable capitalization of the resources from the Danube Delta. Being one of the most important tourist regions in Romania, the development of tourism in the Danube Delta is one of the structural interventions that can contribute to the economic development of local economies, but it is the activity that cannot give economic sustainability, requiring complementary activities, encouraged by policies at the level of growth centers. Increasing the complexity of the economic profile of the localities in the Danube Delta must be one of the objectives of territorial management, the current situation being generating major imbalances, the most important being the migration of the active population to polarization centers. The development of the Danube Delta through the contribution of tourism must be achieved by establishing a balance between generating revenues from local resources and environmental protection, an objective that can be achieved through a territorial planning policy adapted to the specificities of this geographical area. The sustainable economic development of the Danube Delta is conditioned by the elaboration of an economic and social development strategy, which should include both the strategic objectives and the action plan. The major components to be addressed by this strategic document are: the development of road infrastructure and its connection with the national road network, establishing the status of growth center for the localities in the Danube Delta that have development potential, establishing special status for job-creating investments for the local population, encouraging the widespread use of green energy. The realization of the strategic instrument must be based on an objective diagnosis of the territorial system based on the numerous studies aimed at the Danube Delta [16, 50–60]. Acknowledgements The research was supported by a grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI, project number PN-III-P4-ID-PCE-2020-1076, within PNCDI III and two grants of the University of Bucharest, Romania, project number 10680 UB and 10681 UB.

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The Role of Tourism Activities in the Integrated Economic Development of the Danube Delta Radu-Daniel Pintilii, Andreea Karina Gruia, Alexandra Grecu, Oana Cret, u, and Donatella Carboni

Abbreviations DDBR: GDP: MaB: MAP: NACE: PAs: UNESCO: WTTC:

The Danube Delta Biosphere Reserve Gross Domestic Product Man and the Biosphere Madrid Action Plan Classification of Activities from the National Economy protected natural areas United Nations United Nations Educational, Scientific and Cultural Organization World Travel and Tourism Council

R.-D. Pintilii (B) · A. K. Gruia · A. Grecu · O. Cret, u Research Center for Integrated Analysis and Territorial Management, University of Bucharest, 030018 Bucharest, Romania e-mail: [email protected] A. K. Gruia e-mail: [email protected] A. Grecu e-mail: [email protected] O. Cret, u e-mail: [email protected] A. K. Gruia · A. Grecu Faculty of Business and Administration, University of Bucharest, 030018 Bucharest, Romania D. Carboni Department of Humanities and Social Sciences, University of Sassari, 07100 Sassari, Italy e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_13

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1 Introduction Tourism sector is significant from the economic point of view for indicating the development level of one country, because it generates direct and/or indirect many other opportunities and benefits both for tourists and resident people, too [1]. Tourism development could be an essential tool for promoting the economic growth [2] of a local community, being an important source of income, increasing the Gross Domestic Product (GDP) [3]. The World Travel and Tourism Council (WTTC) 2019 report, analyzing travel and tourism impact, shows a 10.4% of global GDP share of tourism, and 319 million jobs globally (10% of the total employment) [4]. It is a very dynamic and adaptive economic sector that implies the actors’ good skills to face a continuous change that this sector occurs. The tourism economic development is also increasing due to the quality of resources and environment [5] and sustainable tourism development could be considered as an alternative way to poverty alleviation [6–11]. For the countries in transition, tourism could represent a good strategy for development, useful to accelerate the convergence with the countries for the West [12–15]. To answer the following question “How could tourism determine the economic growth in the local economies?”, the tourist arrivals in one destination could be reflected in the economic growth in two possible ways: one way consist in the money spent by tourists on basic services (transportation, lodging, meals, attractions visiting, shopping, souvenirs, and entertainment), as a direct spendings that goes directly to companies (investments, profits), households (wages, tips, services), and government (fees, taxes, goods, and services). The second way to answer the question is by the indirect effects on the GDP through productivity spillovers. A good example is when the companies dealing with the international hospitality bring knowledge, high skilled staff, and new ideas in a destination. Also, they could influence the local entrepreneurs by implementing and using the same comparable standards and quality for goods and services they offer (as a sign of good practices) [15–19]. Tourism sustainability represents a key factor for future development nowadays, and it has been involved in long debates by many policymakers and practitioners [20–24]. During the last two decades, the policy and especially the practical initiatives in the field of tourism have proliferated globally, and many actors acknowledged its crucial role in sustainable development [25]. Nowadays, sustainability is the word well describing the tourism sector. It is also a paradigm that traces the future for this sector, which manifests itself in various other forms: ecotourism, rural tourism, nature-based tourism, heritage tourism, community tourism, creative and civic tourism [26–29]. Tourism is also a growing economic sector, that use natural environments, which has become important to consider in defining the exploitation and the management of protected natural areas (PAs). The interaction between natural environments and the human activities are in continuous change and evolution under the pressure of various challenges, including tourism development [30, 31]. The PAs of a territory are also considered a tool for the environmental policy among other tools and, by a proper exploitation, for example by sustainable tourism activities, could represent a resource with significant added value for the European

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Regions. However, the unproper operation of PAs, could have a negative impact on the natural environment and that’s why to adopt sustainable tourism policies it is crucial to obtain appropriate sustainable development [32–34]. The general purpose is represented by the protection of those vulnerable areas and especially of their resources, that promote a sustainable tourism, through coherent sustainable strategies [35]. Such areas could be pioneer demonstration areas on the one hand for the economic and social development, and on the other for the ecological environmental protection and technological innovation. They could provide some new ideas for obtaining some benefits (economic, social, and environmental), and for achieving green and balanced development [36]. In the last three decades, PAs are shaping the settings for the sustainable tourism development. They could offer many recreation and learning opportunities and contribute to human well-being [37]. In terms of community development, many areas on Earth depend on protected areas (PAs), viewing their role as important natural resources [38, 39]. The concept of livelihood implies to those capabilities, assets, and activities required to make a living [40]. The rural communities’ point of view, they are strongly influenced by the coherent traditional livelihood strategies such as agriculture, forestry, fishing, livestock rearing, and handicrafts [41, 42]. The Biosphere reserve represents a United Nations (UN) designation that demand a region should follow the principles of sustainable development [43]. In 1974, UNESCO initiated the biosphere reserves by its program Man and the Biosphere (MaB), as a concept, but the first generation of Biosphere Reserves were inaugurated two years later, in 1976. The second one was designated in 1984. Starting with 1995, the Seville Strategy was adopted by UNESCO, as a statutory framework for future biosphere reserve developments. In 2008, The Madrid Action Plan (MAP), another document built on the 1995 Seville Strategy, shows the how biospheres can effectively respond to and help address global issues and problems that have emerged or increased since 1995 [43–46]. The UNESCO Report (2008) underlined that these major challenges have a multiplier effect by contributing to increase poverty and inequality, to accelerate climate change, to determine a rapid loss of biological and cultural diversity and to accelerate the process of urbanization, all these with major implications on environmental change [47]. Tourism has a bivalent structure and is mostly builds on the divisions: nature—culture, work—play, housing area— industrial area—recreational area etc. [48, 49].

2 Methodology 2.1 Study Area The study area (Fig. 1) is represented by the eight territorial administrative units (TAUs) situated entirely in the Danube Delta and other 21 TAUs situated partially on that territory. The Danube Delta Biosphere Reserve (DDBR) is an ecosystem of

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Fig. 1 Localization of administrative-territorial units from the Danube Delta (Data source ©OpenStreetMap contributors)

water and land belonging to Romania and Ukraine countries. This territory is made up of water channels, lakes, and small islands at the last part of the Danube. This ecosystem is the largest European wetland and reed, an area of birdlife (for over 300 bird species), most of them using this area for stopover and breeding. About 90 fish species are present in the water, including the one of the most valuable populations of fish—the sturgeon (Acipenser), and other mammals as the wildcat (Felis silvestris), the European mink (Mustela lutreola), the freshwater otter (Lutra lutra) and the monk seal (Monachus monachus), this latter, as the globally threatened one [49]. As a cultural space, important for the tourism activities the Danube Delta is also a mixture of people (Bulgarian, Gagauz, Lipovan, Moldovan, Russian, Turkish and Ukrainian people), spread all over the area in their small and coquettish villages. Among the main economic branch of activities in the area are fishing, hunting, reed harvesting, livestock raising and subsistence agriculture, as well as tourism activities could be highlighted [50].

2.2 Data Analysis An economic database has been created at the level of administrative-territorial unit, at the level of 4-digit NACE code (Table 1), highlighting the main economic indicators important for the analysis of the Tourism field—number of companies and of employees, turnover, and profit, according to the Classification of Activities from the National Economy (NACE codes). The analysis period for the economic indicators is 2000–2018.

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Table 1 Classification of NACE codes belonging to the field of Tourism NACE codes

Activities

Field of activity according to NACE

5510

Hotels and similar accommodation

5520

Holiday and other short-stay accommodation

ACCOMMODATION AND FOOD SERVICE ACTIVITIES

5530

Camping grounds, recreational vehicle parks and trailer parks

5590

Other accommodation

7911

Travel agency activities

7912

Tour operator activities

7990

Other reservation service and related activities

ADMINISTRATIVE AND SUPPORT SERVICE ACTIVITIES

Graphical models show the evolution of total value and the share of values in the field of Tourism in the total economy both for the administrative-territorial units whose territory is entirely in the Danube Delta Biosphere Reservation and the administrative-territorial units located partially on the territory of the DDBR for number of companies and employees, the value of turnover and profit. The data used for the analyzes performed are part of the UB 1365 Project “Spatial projection of economic pressure on the forest ecosystem”. The economic indicators turnover and profit values are expressed in the National currency unit (Romanian leu(i); 1 leu = 0,20 euro).

3 Results 3.1 Indicators for the Accommodation 3.1.1

Tourism Establishment Units

From the point of view of dimension and quality of services in a territory, the accommodation facilities play an important role in tourism promotion and development. They must be drawn in the context of the recent trends of the tourism market. As an objective diagnosis, in the newest territory of the Danube Delta, there are over 300 accommodation units. If until 2009 the number was very low (under 50 units in the territory situated entirely in the area, and 100 units in the territory partially in it, after that it easily increased. In the last two years we assist to a double number (over 100 and over 200), especially in the municipalities partially situated in the Danube Delta (Fig. 2).

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350 300

NUMBER

250

Establishments of touristic reception with functions of tourists accommodation (entirely in the Danube Delta) Establishments of touristic reception with functions of tourists accommodation (partially on the territory of the Danube Delta) Establishments of touristic reception with functions of tourists accommodation (total number) Linear (Establishments of touristic reception with functions of tourists accommodation (entirely in the Danube Delta)) Linear (Establishments of touristic reception with functions of tourists accommodation (partially on the territory of the Danube Delta)) Linear (Establishments of touristic reception with functions of tourists accommodation (total number))

200 150 100 50 0

Fig. 2 Tourism accommodation (no. of units) (Data source National Institute of Statistics)

The total number of the accommodation units follows the same evolution, an easily upward evolution until the Global Economic Crisis (2007–2008), then another decrease (2010–2011), a relative stabilization until 2017, and a spectacular increase for the last two years, for both categories of municipalities. The linear trends are positive for the total accommodation units and for those situated partially on the territory and constant (no positive and negative direction) for those situated entirely in the Danube Delta.

3.1.2

The Accommodation Capacity, By Type

Regarding the accommodation number of places by type, in that territory most of it Biosphere reserve, the possibilities of construction and the legislation restriction give the possibility for a large number of places in the agrotourism pensions, if we consider the large consume of local gastronomy in the territory. So, in the Fig. 3, the large number of places is for the structures of accommodation on short term, and for agrotourism pensions and other such units (hotels, tourism villas, campgrounds, tourism stops, etc.), the number of places increase for the last years. One of them constantly increases (number of places in hotels and agrotourism pensions). For the others the increase trend is seen after a big fall (hostels, tourist villas, campgrounds and tourist stops). Other complementary accommodation units are specific for this territory and in the last period, the number of places increases too (bungalows, accommodation on river and sea vessels).

The Role of Tourism Activities in the Integrated Economic … Tourist villas (total number)

Hotels (total number)

Tourist villas (entirely in the Danube Delta)

Hotels (entirely in the Danube Delta) number

Tourist villas (partially on the territory of the Danube Delta)

Hotels (partially on the territory of the Danube Delta)

2,500

number

Linear (Hotels (entirely in the Danube Delta))

Linear (Tourist villas (entirely in the Danube Delta))

1,400

Linear (Hotels (partially on the territory of the Danube Delta))

2,000

Linear (Tourist villas (partially on the territory of the Danube Delta))

1,200

1,246

1,000

1,500 2,052

1,728

1,882

1,839

1,836

1,843

1,796

1,795

1,589

1,571

1,485

1,210

1,171

1,051

1,036

900

992

938

788

500

1,066

800

1,000

581

600

452

200

436

516 516

492 492 492 492

64

64

64

96

Bungalows (total number)

Tourist chalets (total number)

Bungalows (entirely in the Danube Delta)

Tourist chalets (entirely in the Danube Delta)

Bungalows(partially on the territory of the Danube Delta)

Tourist chalets (partially on the territory of the Danube Delta)

120

Linear (Tourist chalets (entirely in the Danube Delta))

100

Linear (Tourist chalets (partially on the territory of the Danube Delta))

98

number

50

50

Linear (Bungalows (entirely in the Danube Delta))

500

300

50

48

48

48

48

48

48

188

200

40 20

20

8

8

8

8

8

20

8 0

0

106

100

76

90 20

600

74

400

50 20

29

20

29

29

29

29

29

29

29

32

32

134 0

Camps for pupils and preschoolers (entirely in the Danube Delta)

855

800

Camps for pupils and preschoolers (partially on the territory of the Danube Delta) Linear (Camps for pupils and preschoolers (entirely in the Danube Delta)) number

855

Linear (Camps for pupils and preschoolers (par tially on the territory of the Danube Delta))

1,000 800

600

793

725 717 717

600

400

632

549

620

558

400 0

40

52

62

94

110

95

88

103 103 124 124 116

170 154

300

Agrotourism pensions (total number) Agrotourism pensions (entirely in the Danube Delta)

Tourist pensions (partially on the territory of the Danube Delta) Linear (Tourist pensions (entirely in the Danube Delta)) Linear (Tourist pensions (partially on the territory of the Danube Delta))

500

203

173

152 150

1,000

85

500

0

0

Accommodation on river and sea vessels (total number)

500

64

64

153

285 223 366 360 253

462

588 354

208

483 505 395 358 271

Apartment hotels (partially on the territory of the Danube Delta) Inns and motels (partially on the territory of the Danube Delta)

Accommodation on river and sea vessels (par tially on the territory of the Danube Delta)

600

0

Hostels (entirely in the Danube Delta)

Accommodation on river and sea vessels (entirely in the Danube Delta)

number

2,631 2,553

2,000 1,500

193

175 161

81

Linear (Agrotourism pensions (partially on the territory of the Danube Delta))

2,500

256 250 237 237 242

124 127 69

100

Linear (Agrotourism pensions (entirely in the Danube Delta))

3,000

540

313

300

Agrotourism pensions (partially on the territory of the Danube Delta)

number

400

200

0

0

0

Tourist pensions (entirely in the Danube Delta)

600

249 249 210 200 200 214 214

180

170

200

Tourist pensions (total number)

number

674

322

310

300 300 300

Camps for pupils and preschoolers (total number)

Linear (Tourist stops (partially on the territory of the Danube Delta))

0

794

730 730

Tourist stops (entirely in the Danube Delta)

1,000

0

0

430

Tourist stops (total number)

Linear (Tourist stops (entirely in the Danube Delta))

0

0

0

number

0

730 730 730 730

454 454

Tourist stops (partially on the territory of the Danube Delta)

0

0

200

0

200

0

956 810

0

0

Linear (Campgrounds (partially on the territory of the Danube Delta))

800

109

0

0

Linear (Campgrounds (entirely in the Danube Delta))

1,000

156

0

0

Campgrounds (partially on the territory of the Danube Delta)

1,200

Linear (Holiday villages (partially on the territory of the Danube Delta))

50

0

Campgrounds (entirely in the Danube Delta) number

Linear (Holiday villages (entirely in the Danube Delta))

100

20

Campgrounds (total number)

Holiday villages (partially on the territory of the Danube Delta)

150

78

0

0

Holiday villages (entirely in the Danube Delta)

200

78

76

Holiday villages (total number)

number

452 436

Linear (Bungalows(partially on the territory of the Danube Delta))

400

74

80

0

570 538 396

176

0

number

Linear (Accommodation on river and sea vessels (entirely in the Danube Delta))

number

Motels (partially on the territory of the Danube Delta)

Linear (Accommodation on river and sea vessels (partially on the territory of the Danube Delta))

500

Inns (partially on the territory of the Danube Delta)

506

400

400

Tourist houses (partially on the territory of the Danube Delta)

460

300

300

200

180

200 66

100 0

516 558

400

0

60

369

0

0

10

96

99

117

121 140 72

46

48

30

98

140 140 140

100 0

Fig. 3 Accommodation capacity by type (number of places) (Data source National Institute of Statistics)

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3.2 Indicators for the Tourism Activity 3.2.1

Tourist Arrivals

To characterize the tourism activity of a territory, the attractiveness and the dimension travel in that area, the tourist arrivals act as an important indicator. The number of the tourist arrivals and overnight stays is very important as the popularity of the area is as well as a singer’s popularity. The more fans for a singer are, the more popular it is. For tourism area is the same, the more are the number of visitors (arrivals) the more important that area is. The linear trend for the tourist arrivals in the Danube Delta (Fig. 4), both for localities entirely and partially on the territory, is constantly increasing. This means that this tourism destination has a big demand for spending free time for the national tourists and the foreign ones. The scale of evolution of tourist arrivals for the localities situated entirely in the Danube Delta is lower than the other, due to the direct or direct restrictions for anthropogenic activities in the core space, directly imposed by the accessibility or characteristics of a biosphere reserve, and indirect imposed by the level of prices. Although, the indicators increase, most tourists prefer the localities situated partially in the area, so the number of arrivals is higher (up to 140.000 arrivals), as for the other, only up to 40.000 arrivals. For both the destinations, the evolution is in the same trend, but for the last two years the growth is spectacular, the Danube Delta being more preferred by the Romanian tourists (Fig. 4). Arrivals of tourists accommodated in the structure of tourists reception (entirely in the Danube Delta)

number 200,000

Arrivals of tourists accommodated in the structure of tourists reception (partially on the territory of the Danube Delta) Arrivals of tourists accommodated in the structure of tourists reception (total number)

180,000

Linear (Arrivals of tourists accommodated in the structure of tourists reception (entirely in the Danube Delta)) Linear (Arrivals of tourists accommodated in the structure of tourists reception (partially on the territory of the Danube Delta)) Linear (Arrivals of tourists accommodated in the structure of tourists reception (total number))

160,000 140,000 120,000 100,000 80,000 60,000 40,000 20,000

2018

Fig. 4 Tourist arrivals in the Danube Delta (Data source National Institute of Statistics)

2019

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2006

2007

2005

2004

2003

2002

2001

0

The Role of Tourism Activities in the Integrated Economic …

371

Touristic overnight stays (total number) Touristic overnight stays (entirely in the Danube Delta)

number

500,000

Touristic overnight stays (partially on the territory of the Danube Delta) Linear (Touristic overnight stays (entirely in the Danube Delta))

400,000

Linear (Touristic overnight stays (partially on the territory of the Danube Delta))

300,000 200,000 100,000 0

Fig. 5 Tourist overnight stays (Data source National Institute of Statistics)

3.2.2

The Tourist Overnight Stays

The tourist overnight stays (Fig. 5) present the same evolution, a moderate evolution with high and low variations, and big increasing values for the last two years of the period (2018 and 2019). If for the territory entirely in the Danube Delta, the values have no spectacular differences, the most dynamic is for those that are partially in the Delta. This fact is caused by the traditional arrivals (tourists that each year visit the core of the Danube Delta), and the fluctuation being induced by the occasionally tourists (visitors) of the Delta.

3.2.3

The Average Length of Stay at Tourist Accommodation

One of the most important indicators for the tourism activity of an area is the Average length of stay at tourist accommodation (Fig. 6), that reflects the attractiveness for that destination. In the figure below, for the period 2001–2019, a general downward trend could be observed for the territorial administrative units situated entirely in the Danube Delta. In the area situated entirely in the Danube Delta, the values decrease from 5 days (reflecting an average about one week per stay), to values close to 3 in the last three years (that means a period of stay for a weekend). For these municipalities, the highest average length of stay is 5,29 (2002) and the minimum is 2,12 (2010). For the municipalities partially situated in the Danube Delta, the situation is a little bit different, all the values being considerably lower than in the core of the Delta. The highest value is recorded in 2006 (2,40 days), one year before the Global Economic Crisis. A close value could be met in 2013 (2,27 days). The minimum value for these localities is 1,40 (2012). No direction of evolution could be observed in the linear trend of these values.

372

R.-D. Pintilii et al. Average duration of the touristic stay (entirely in the Danube Delta) Average duration of the touristic stay (partially on the territory of the Danube Delta) Average duration of the touristic stay (total number) Linear (Average duration of the touristic stay (entirely in the Danube Delta)) Linear (Average duration of the touristic stay (partially on the territory of the Danube Delta))

days

6.00

4.52

2.80 2.09

2.79 2.09

1.85

1.83

1.69

1.97

2.67

3.14

3.97 3.00 2.27

2.39 1.40

2.25 1.48

1.48

1.66

2.12

2.14

2.38 1.69

1.87

1.93

1.71

1.87

2.03

1.00

2.06

2.00

2.40

2.68

3.00

2.82

3.72

4.13

4.49

4.67

4.00

5.29

5.00

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

0.00

Fig. 6 Evolution of the average duration of the tourist stay in the administrative-territorial units from Danube Delta (Data source National Institute of Statistics)

3.2.4

The Occupancy Rate

Another important indicator for tourism activity is the Occupancy rate (Fig. 7), which shows how efficient tourism activity is in the area. In the figure below, the occupancy rate for the localities situated entirely inside the Danube Delta, for the period 2001– 2019 an oscillating evolution could be observed. For the last 10 years the indicator recorded highest interval values, 2019 being the peak (50,65%). The minimum value could be found for 2004 (7,13%) and the linear marks an upward trend. Until the economic crisis, the evolution knew the lowest values, this year, a change could be observed in the evolution of the indicator.

35.12

16.37

12.64

7.13

12.64

10.59

14.72

25.45

23.01

19.04

21.02

20.80

36.99

37.81

25.09

31.37

17.86

34.36

50.65

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

18.16

20.35

20.58

22.39

30.60

33.05 20.24

19.12

22.42 15.69

14.72

10.00

2001

20.00

20.11

27.76

23.06

22.55

30.00

29.66

40.00

34.66

50.00

30.63

60.00

31.11

Touristic occupancy rate (entirely in the Danube Delta) Touristic occupancy rate (partially on the territory of the Danube Delta) Touristic occupancy rate (total number) Linear (Touristic occupancy rate (entirely in the Danube Delta)) Linear (Touristic occupancy rate (partially on the territory of the Danube Delta))

%

0.00

Fig. 7 Evolution of the occupancy rate in the administrative-territorial units from Danube Delta (Data source National Institute of Statistics)

The Role of Tourism Activities in the Integrated Economic … Code 5510 (partially on the territory of the Danube Delta)

Code 5510 (entirely in the Danube Delta)

Code 5530 (partially on the territory of the Danube Delta)

Code 5590 (entirely in the Danube Delta)

Code 5590 (partially on the territory of the Danube Delta)

79 68

62 62

28 28 29 25 27

19

109

32

44 41 42 40 42 38 40 36

84

64 53

50

47 45

41

39 21

21

22

20

23 23

24

27

25

25 25

26 24

23

52 54 52 50 48 50 48 48 48

43

25

18

19 19

19 17

13

18

17

2017

2015

2013

2011

2009

2007

2005

2003

2001

2018

2016

2014

2012

16 14

8

8 5

5 0

0

1

1

1

1

1

1

1

1

1

2

2

3

2

1

2

4 2

5 2

6 2

5 3

3

3

3

3

3

3

3

3

5

6

6

6

6

3 1

1

1

1

1

2

2

2

2

2

2

3

3

3

3

3

2

4

4

4

4

4

4

4

3

3

3

3

3

3

3

5

5

2

3 2

2

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

0

16

12 10

10

0

2010

21 21

20 18

15

10

2008

Code 7911 (partially on the territory of the Danube Delta) Code 7912 (partially on the territory of the Danube Delta) Code 7990 (partially on the territory of the Danube Delta)

25

17

15

2006

2004

2002

2000

2017

2015

2013

2011

2009

2007

2005

2003

2001

2018

2016

2014

2012

2010

2008

2006

2004

2002

Code 7911 (entirely in the Danube Delta) Code 7912 (entirely in the Danube Delta) Code 7990 (entirely in the Danube Delta)

25

0

45

32

28

18 16 16 15 16 14 15 16 16 12 14 14 15 16 13 15 11 31 10 10 12 8 6 6 6 7 7 7 6 28 6 5 7 5 5 5 5 5 4 5 5 5 4 5 5 6 6 6 6 6 5 3 24 2 2 3 2 3 2 2 2 2 3 2 2 2 2 3 3 3 4 19 21 21 21 11 16 18 18 2 3 5 5 6 9 8 10

13

30

number of employees

Code 5520 (partially on the territory of the Danube Delta)

Code 5530 (entirely in the Danube Delta) 107

2000

number of companies

Code 5520 (entirely in the Danube Delta)

120 110 100 90 80 70 60 50 40 30 20 10 0

373

Fig. 8 Evolution of the total number of companies from Tourism for the administrative-territorial units whose territory is entirely, and the administrative-territorial units located partially on the territory of in the Danube Delta (Data source UB 1365)

The situation is a little bit different for the localities partially on the territory of the Danube Delta, the linear records no direction of evolution, but regarding the values of the indicator, they are higher as in the previous case, for the first part of the interval (2001–2008), with over 30% (34,66% in 2008) and lower for 2009–20,012 (about 20%—22,42% for 2009). For the 2013 and the last two years of the interval (2018 and 2019) the values are like the first part of the interval (30,60%—2018 and 35,12%—2019). In the Fig. 8, the NACE codes 5510 to 5590 are associated to the accommodation facilities and regarding the number of companies in the localities situated entirely and partially to the Danube Delta, the evolutions show an upward trend. If for the most kind of facilities the evolution is a moderate one, the most spectacular they are for the holiday and short period (5520). For 5510 NACE code and for the localities partially situated on the territory of the Danube Delta, the values increase from 13 companies in 2000 to 45 companies in 2018, after a break in 2012 from 44 companies to 38 in the next year. Moderate values there are for those localities that are entirely in the Danube Delta. After some oscillations, the values increase from 2 (2000) to 5 (2018). A spectacular increasing could be noticed for the 5520 NACE code (Accommodation facilities for holidays and short periods), especially for the localities partially in the Danube Delta. Although both kind of them (entirely and partially in the Danube Delta), the values start from 2 companies for this NACE code in 2000, for 2004 a disrupter in the evolution appears. The values suddenly increase with great values for the localities partially in the Danube Delta, reaching 109 companies; in comparison with the others, where the maximum value is 31 (2018). Lower values are registered for the companies belonging to the 5530 NACE code (Caravan parks, campsites,

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and camps). These values could be explained due to the lack of accessibility, in that territory. A moderate evolution is for the NACE code 5590 (Other accommodation services), after a maximum of 53 companies in 2008 (partially) and 16 companies in 2010 (entirely). Another big difference in evolution is for the 7911 NACE code (Activities of travel agencies), meaning that for a Biosphere reserve, all the tourism activities should be organized. The municipalities situated entirely in the Danube Delta benefits from the large number of such companies. There is an oscillatory evolution from 1 to 2 companies for the others. A moderate evolution is for 7912 NACE code (Tour operator activities) who effectively organize the tours in Danube Delta territory (from 2 to 6 in the entirely territory and 4 to 16 in the partially territory). No big differences are observed for the 7990 NACE code (Other reservation services and tourist assistance), the values oscillate from 1 company (2000) to 2 companies (2018) for both situations. Especially important is the share of the number of companies from tourism in the total number of companies (Fig. 9) where, excerpt 5530 and 7790 NACE codes where the linear trend is decreasing, all other NACE codes register spectacular growths for the linear trends. The most spectaculars growths are for 5510, 5520, 5590 and 7991 NACE codes. Big differences between the values for the municipalities entirely and partially situated in the Danube Delta are for the NACE code 5510, 5520, 5530, 5590, 7912 and 7990. The values for the NACE code 7911 the values intersect themselves in different years of the period. Important variations are for the evolutions of the turnover from tourism activities values (Fig. 10), the 5510 NACE code knows a big growth, from under 10.000.000 lei in 2000 to over 70.000.000 lei in 2018. The same situation is for the 7911 NACE code, but the situation is moderate for the 7912 NACE code. There are the other NACE codes to the opposite sides, where the values do not exceed 25.000.000 lei. For the share of turnover in Tourism in total economy (Fig. 11) for all the administrative-territorial units (entirely and partially on the territory of DDBR), excerpt 5590 NACE code, where the linear trend decreases, all others are situated on a positive trend. Some of the economic activities register big growths in the first quartile in the interval (5590), this one drawing a decreasing till the rest of the years. Others, know different situations: big values for the middle of the period (5510) some at the end of the period (7911) and other for the entire interval (7912). Being a region, characterized by a strong seasonality of the tourism activities (Fig. 12), the evolution of the number of employees is different from an economic activity to another. Remarkably interesting is that, with one exception (5510 NACE code), no high values could be observed in the rest of them. The 7911 NACE code register a big decreasing, from over 100 employees in 2005 to under 40 at the end of the period. For the rest of the NACE codes, the number of the employees are under 100. This kind of activities implies a lot of part time jobs, that is why the oscillatory evolution could be explained for some codes. The evolution of the share of number of employees in Tourism activities in total economy (Fig. 13) for the administrative-territorial units whose territory is entirely, and the administrative-territorial units located partially on the territory of in the

The Role of Tourism Activities in the Integrated Economic …

375

Fig. 9 Evolution of the share of number of companies in Tourism in total economy for the administrative-territorial units whose territory is entirely, and the administrative-territorial units located partially on the territory of in the Danube Delta (Data source UB 1365)

DDBR, the figure related shows no important values (up to 10%). That could be explained by the incipient activity of tourism among the localities of the Danube Delta. Or, another explanation is the belonging of the employees to the other companies, eventually located outside the area (having their headquarter in Bucharest or other big city of Romania), who could relocate their employees, according to their seasonal needs. The graphs reflecting the evolution of the total profit from tourism illustrate that the most profitable are the 5510, 7911 and 7912 NACE codes, all of them for the administrative-territorial units located partially on the territory of in the DDBR (Fig. 14). They reach high values up to 12.000.000 lei (in 2017 for 5510 NACE

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R.-D. Pintilii et al. Code 5510 (entirely in the Danube Delta)

Code 5510 (partially on the territory of the Danube Delta)

Code 5520 (entirely in the Danube Delta)

Code 5520 (partially on the territory of the Danube Delta)

Code 5530 (entirely in the Danube Delta)

Code 5530 (partially on the territory of the Danube Delta)

Code 5590 (entirely in the Danube Delta)

Code 5590 (partially on the territory of the Danube Delta)

8,00,00,000 lei 7,00,00,000 lei 6,00,00,000 lei 5,00,00,000 lei 4,00,00,000 lei 3,00,00,000 lei 2,00,00,000 lei

Code 7911 (partially on the territory of the Danube Delta)

Code 7912 (entirely in the Danube Delta)

Code 7912 (partially on the territory of the Danube Delta)

Code 7990 (entirely in the Danube Delta)

Code 7990 (partially on the territory of the Danube Delta)

2017

2013

2015

2011

2007

Code 7911 (entirely in the Danube Delta)

2009

2003

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2005

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2014

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2002

0 lei

2000

1,00,00,000 lei

80,00,000 lei 70,00,000 lei 60,00,000 lei 50,00,000 lei 40,00,000 lei 30,00,000 lei 20,00,000 lei 0 lei

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

10,00,000 lei

Fig. 10 Evolution of the total turnover from Tourism for the administrative-territorial units whose territory is entirely, and the administrative-territorial units located partially on the territory of in the Danube Delta Biosphere Reservation (Data source UB 1365)

code-corresponding to hotels and other accommodation facilities) and 1.200.000 lei for the other two NACE codes (7911 and 7912), reflecting the activity of the tour operators and travel agencies. The values for evolution of the share of profits in the economy are higher for the same NACE codes categories, showing that the importance of tourism activities in the Danube Delta is higher, especially in the summer season. With values up to 20% is 5590 (other accommodation services), 5520 (accommodation facilities for holidays and short term). They are the most profitable activities for a territory with a very specific kind of tourism in a specific period of the year. The most dynamic evolutions are for the localities situated entirely in the territory (Fig. 15).

4 Conclusions Tourism is the most important component of the economy of the territorial systems of the Danube Delta, being the preeminent element for a sustainable development of the local economy. The sustainable use of the natural and anthropic heritage, of world importance, is the main objective of the territorial management strategies. Supporting economic activities in the Danube Delta through structurally provided fiscal facilities is an important direction of action. Thus, there is a need to develop tourism infrastructures adapted to the local specific (to meet quality and sustainability standards, economically viable) in geographical areas concentrated in growth centers

The Role of Tourism Activities in the Integrated Economic … 7.00 6.00

Code 5510 (entirely in the Danube Delta)

7.00

Code 5520 (entirely in the Danube Delta)

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and based on well-founded strategies on the administrative territory of other administrative units. The infrastructures to be supported are: accommodation and catering units, tourist information centers, light physical infrastructures for bird watching activities (birdwatching), infrastructures for micromobility, other leisure activities. The tourism development of the Danube Delta must take into account the principle of integration, so the visitor centers (mentioned in the tourism development strategy) must be integrated into a unitary system of interpretation of nature and anthropic resources.

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Regarding the organization of tourism, it is recommended to introduce a sustainability tax for each tourist entering the Danube Delta, the revenues obtained by supporting the management system to ensure compliance with the specific rules of a fragile ecosystem. The control of the tourist flows that enter the Danube Delta is absolutely necessary for the optimization of the taxation of the revenues obtained from tourism. Support services for the development of tourism in the Danube Delta is a weak point, future actions must include concrete steps for the development of health services, safety and security of tourists, which must rise to international standards to help increase the competitiveness of the local economy. The detailed analyzes on tourism in the Danube Delta highlighted the rethinking of the transport system, the geographical isolation being the main cause of the economic decline. Reconsidering the road transport system (with environmentally friendly transport units), and mobility in general, is an indispensable direction for the sustainable development of the Danube Delta. Thus, in the development strategy, the growth poles of Chilia Veche and Sulina must be supported, which, connected by road, would give a major impetus to the development of the studied area. Water transport is dominated today, but high costs and high pollution make it restrictive for sustainable development. The lack of manpower and skilled labor forces to attract young people to the Danube Delta and to improve the capacity and skills of tourism staff. Also, the

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Fig. 13 Evolution of the share of number of employees in Tourism in total economy for the administrative-territorial units whose territory is entirely, and the administrative-territorial units located partially on the territory of in the Danube Delta (Data source UB 1365)

development of tourism is conditioned by the generation of chains of economic activities that capitalize on the economic resources of this geographical area in close connection with tourism activities. The sustainable development of the Danube Delta is determined by the realization of a territorial management system based on consulting local actors and reconsidering them in the decision-making process, rethinking mobility and developing tourism to international standards. The results achieved can be complemented in the future by structural approaches that provide a better understanding of the pressure of economic activity on the ecosystem. Thus, new methodologies are needed to provide information on the development of indicators relevant to the sustainability of the ecosystem. In this respect, imaging analysis can make a significant contribution [51–54].

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Fig. 14 Evolution of the total profit from Tourism for the administrative-territorial units whose territory is entirely and the administrative-territorial units located partially on the territory of in the Danube Delta (Data source UB 1365)

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Fig. 15 Evolution of the share of profit in Tourism in total economy for the administrative-territorial units whose territory is entirely, and the administrative-territorial units located partially on the territory of in the Danube Delta (Data source UB 1365)

Acknowledgements The research was supported by a grant of the Romanian Ministry of Education and Research, CNCS—UEFISCDI, project number PN-III-P4-ID-PCE-2020-1076, within PNCDI III and two grants of the University of Bucharest, Romania, project number 10680 UB and 10681 UB.

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Danube Delta Integrated Sustainable Development Strategy Daniel Constantin Diaconu, Mihnea Cristian Popa, Daniel Peptenatu, and Abdelazim M. Negm

1 Introduction Territorial cooperation and technology flow, assets, and capital are critical aspects of the development process and essential factors supporting sustainable development. Sustainable development goals are global goals for environmental protection and human development by 2030 [1]. Eradicating all forms and dimensions of poverty and the sustainability of resources is the biggest global challenge and an indispensable requirement for sustainable development, given that poverty is a multidimensional problem that transcends borders. Globally, over 800 million people still live on less than $ 1.25 a day [2]. Mordvinov et al. (2021) present specific proposals for improving the institutional, functional, organizational, and financial foundations of state influence on

D. C. Diaconu (B) Faculty of Geography, Department of Meteorology and Hydrology, University of Bucharest, Bucharest, Romania e-mail: [email protected] D. C. Diaconu · M. C. Popa · D. Peptenatu Research Center for Integrated Analysis and Territorial Management, 030018 Bucharest, Romania e-mail: [email protected] D. Peptenatu e-mail: [email protected] M. C. Popa Simion Mehedini-Nature and Sustainable Development Doctoral School, University of Bucharest, Bucharest, Romania A. M. Negm Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 A. M. Negm and D. C. Diaconu (eds.), The Danube River Delta, Earth and Environmental Sciences Library, https://doi.org/10.1007/978-3-031-03983-6_14

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social processes in the regions, affirming the need for state institutions to support disadvantaged areas [3]. The Romanian deltaic space has been in the attention of the central authorities over time. The investments made are different in value and territory depending on local and European public policies. Thus, the concept of Integrated Territorial Investment (ITI) was introduced as the primary vector for implementing territorial development at subregional, regional, national, or cross-border levels [4–6]. The improvement of infrastructure elements, supported by laws adaptive to the development stage and a healthy political framework, form the backbone of human settlements. Aspects of forecasting and risk reduction, of whatever nature (economic, social, demographic, environmental), reduce the probability of occurrence of the phenomenon or its impact. Thus, the spatial planning activity, also known as urbanism, develops land use planning to shape the space, distribution, and interconnection of land use and economic activities (Figs. 1 and 2) [7, 8]. All these strategies are developed and refined with the involvement of citizens to legitimize public policies. However, participation rhetoric does not necessarily imply truly democratic situations of citizen involvement. The validation of the implemented policies can be done by boiled methods to confirm the effectiveness of the adopted measures. Kataeva et al. (2019) analyze the aspects of territorial marketing and their influence on the spatial development of the territory and the financial components of this issue [9]. They concluded that the financing of the spatial development of the region is

Fig. 1 Road network (Data source © OpenStreetMap contributors)

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done mainly using federal and regional budgetary funds in the development strategy. Using the methods of logical, abstract judgments and expert evaluations, a process of strategic positioning of the territory was developed, with the indication of specific techniques for each stage, based on existing resources and its development prospects by attracting additional funds.

2 Study Area The Danube Delta is a formation resulting from the interaction of the main factors that govern the coastal areas, respectively, the variation of sea level, currents, tides, and waves, and the flow of water and alluvium transported in the area by the Danube. These conditions are also associated with the submerged, coastal, and marine relief configuration. Danube (Donau, Dunaj, Dunav, Dunarea, Duna) river springs from under the Kandel peak (1241 m), in the Black Forest Mountains, Germany. The two small rivers Brigach and Breg join in the park of Fürstenberg Castle, in Donaueschingen. The Danube flows southeast for about 2860 km and empties into the Black Sea, the only European river flowing west to east. The Danube flows through 10 countries (Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria,

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Moldova, Ukraine), has tributaries from seven other countries, and passes through four state capitals: Vienna, Bratislava, Budapest, and Belgrade. On the territory of Romania, the lower course of the Danube has 1075 km and flows between the towns of Bazias and Sulina, also representing the border with Serbia (235.5 km), Bulgaria (469.5 km), the Republic of Moldova (0.6 km) and Ukraine (53.9 km), collecting most of the rivers in Romania except those in Dobrogea. Morphologically, the Danube Delta is a flat region (plain alluvial) with a slight slope from west to east (0.006%) which is more pronounced in the field of Chile, a witness of erosion in the Bugeac Plain (southern Bessarabia), the Stipoc continental ridge and the Letea and Caraorman marine ridges. With the “0” level of the Black Sea, in the territory of the Danube Delta, 20.5% is below this altitudinal landmark and 79.5% above it. The most significant extensions are the surfaces located between 0 and 1 m. The highest “heights” are found on the sea ridges (Letea 12.4 m, Caraorman 7.0 m), and the greatest depths are located on the branches of the Danube (−39.0 m on the Chilia branch, −34.0 m on the Tulcea branch, −26.0 m on the Sfantu Gheorghe (Saint George) branch, −18.0 m on the Sulina channel). Within the lake units, the depth does not exceed 3.0 m, except for Lake Belciug, which has 7.0 m. The average altitude of the Delta is + 0.52 m. Due to the configuration of the terrain and the presence of the three branches of the Danube, the morphohydrographic units in the continental area are grouped into three large deltaic units: Letea, Caraorman, and Dranov [10]. The Letea unit is located between the branches of Chilia, Tulcea, and Sulina and the seashore, covering an area of about 157,000 ha (44.9% of the delta area). The unit is characterized by hypsometric and genetic diversity (remnants of the Chel and Stipoc predeltaic land, marine (Letea) and fluvial ridges, intensely alluvial depression areas (Sireasa), a vast lake depression (Mati¸ta—Trei Iezere—Merhei) but also by anthropogenic pressure. Approximately 42.8% of its surface is removed from the natural regime by agriculture (Sireasa, Pardina, Babina, Cernovca), forestry (P˘ap˘adia), and fish (Chilia Veche, Maliuc, Stipoc, Obretin, Popina). Between the branches of the Danube and the inland aquatic spaces, it is made through the network of backwaters and channels that feed over 200 lakes of fish interest, located in two large lake complexes: Sireasa—Sontea—Furtuna ¸ and Mati¸ta—Merhei. Fluvial and in the fluvio-maritim, with an area of about 101,300 ha (28.4% of the delta area). In hypsometric and genetic diversity, including marine ridges (Caraorman, S˘ar˘aturile), old river ridges (Rusca, B˘alteni) and lake depression areas (Gorgova-Isac-Uzlina, Ro¸su-Puiu), less evolved. The sites managed by embankment for various economic purposes are less extensive here (13.2%) and include fish (Rusca, Litcov, Murighiol), agricultural (Carasuhat), and forest (Rusca, Murighiol, Carasuhat). After the embankment works and the arrangement of their premises, the Litcov canal and the Ceamurlia backwater were blocked, and the flow of water on the Gorgova canal was limited (since 1990, the Litcov canal was reopened as part of an ecological reconstruction action). In 1982, a new channel was opened (Cri¸san-Caraorman) to exploit the sands from the Caraorman ridge. Having a large flow section, the channel takes over from the Sulina branch between 5–200.0 m3 /s and modifies the water circulation regime in

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the Ro¸su—Lumina—Puiu lake complex with negative consequences in the ecological balance of this unit. In recent years, several channels have been opened, or breaches have been made in the dams of the premises to facilitate the natural access of water in the aquatic complexes (Filat, with a flow of about 30 m3 /s between Litcov and St. Gheorghe, Uzlina between Sf. Gheorghe and the Gorgova complex— Uzlina, Ivancea, the connection channel between Puiu Lake and Erenciuc Lake). In the period 1985–1990, the Sulina—Sf. Gheorghe coastal dam and the accompanying canal were built on the same route to defend the coastal cordon against erosion and water drainage from the Ro¸su—Puiu lake complex to the Sulina and Sf. Gheorghe branche. A spillway was built along the entire length of the dam, near the Ro¸sule¸t backwater, at a reasonably high elevation (+1.30 m), which leads to the storage of a larger volume of water in the complex and the raising of the level of lakes and groundwater in Caraorman ridge with negative consequences on the Caraorman forest (area with complete protection regime) and the locality of the same name. The Dranov unit is the space between the St. Gheorghe channel and Razim lake, with a total area of over 85,000 ha (24.1% of the delta area) and is characterized by the presence of about one-third of the entire surface of a depression area in the part west, with elevations below sea level and a complex of ridges (Crasnicol—Peri¸sor), in the eastern part with altitudes up to 1.50 m. The unit is poorly drained through the network of natural backwaters; there are only 90 small lakes, except Lake Dranov, the largest lake in the Danube Delta (2,170 ha). The degree of arrangement of the unit is relatively high (26.2%) through the agricultural agreement Murighiol-Dunav˘a¸t and the fish arrangements Dranov, Dunav˘a¸t, Holbina, Peri¸sor, Peritea¸sca, Iazurile—Calica, Sarinasuf. Due to the poor water circulation, the processes of biological accumulation in a hydrological regime characteristic of swamp predominated here. Under natural conditions, the seasonal hydrological exchanges between the Sf. Gheorghe branch and the Dranov lake were made through the Cerne¸t and Dunav˘a¸t backwaters. For these reasons and to reactivate the fishing potential of the Razim-Sinoie lake complex, between 1904 and 1906, the Dunav˘a¸t channel (originally called Carol) was dug, and in 1914 the Dranov channel (originally called Ferdinand). Later, other channels were dug for a similar purpose (Crasnicol, between 1933–1935, Lipovenilor, built after 1950, Palade) [11]. The main morphohydrographic units have characteristics specific to deltaic units. The pre-Delta territories are the areas incorporated in the surface of the Delta, which belonged to the Bugeac Plain located north of the Chilia channel and from which they were separated by river erosion. This category includes the Chilia Field and the central part of the Stipoc ridge. They consist of loessoid deposits, differing wildly from neighboring subunits. In the case of the Stipoc ridge, in this situation is found only the central-eastern part where the altitudes are higher (over 2.0 m), the extremities (the westernmost and easternmost) are made up of river deposits. The altitude gradually decreases from north to south and northwest to southeast on the Chilean Field. In the same sense, the loessoid deposits are easily covered by fluvial deposits, and as such, the landscape changes from the appearance of an actual plain to the north to the deltaic one in the south.

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The surface of the pre-Delta territories is estimated at 8,200 ha (2.4% of the Delta area). River ridges result from depositing alluvium in the process of flooding by flooding. They are best individualized along the primary branches on both banks (Chilia, Tulcea, St. Gheorghe, and Sulina), with heights varying along with them, decreasing from upstream to downstream. Apart from the river ridges along the channels, relief forms along the more essential ravines in the Delta. Through the construction of channels and the creation of platforms for the storage of reeds (during the reed capitalization of the Delta), the anthropic ridges were sometimes higher than the natural ones, although narrower. The surface of the river ridges is estimated at 50,250 ha (about 15% of the territory of the Danube Delta). Marine ridges are formed by a marine (determined) and fluvial (subordinate) processes. They are arranged perpendicular to the direction of the main branches of the Danube, constituting morphological dams in the deltaic perimeter. The most significant sea ridges make up the so-called original cordon (Letea, Caraorman, and Crasnicol) which formed around 10,000–11,000 BC, barring the deltaic gulf and forming today’s river delta. This initial cordon is also the boundary between the two compartments—the river delta and the river-sea Delta. The Letea and Caraorman ridges, made up mostly of sandy deposits, represent the resulting wind relief and the vegetal, grassy, and forestry associations on them. The third complex of sea ridges is S˘ar˘aturile, which occupies an intermediate position between those in the original cordon and the coastal cordons themselves by being supported on the shore with the tip (the narrower part) develops in the form of a shingle inwards. The alignments of the Sacalin Island, which still represent a double shore for a short period (years and decades), also fall into the same category. The surface of the sea ridges is estimated at 34,900 ha (10.5% of the surface of the Delta). The hydrographic network is one of the determining subsystems in the deltaic system’s appearance, evolution, and functioning. The main channels of the Danube and the ravines between these branches have evolved depending on the neotectonic factors and the intensity of the clogging process. The process of self-regulation of the hydrographic subsystem in natural conditions started with the first works of correction of the Sulina branch continued with channels built for fishing, reed, and agricultural purposes. Subsequently, numerous enclosures were built for reed farming, fish farming, agriculture, and forestry, requiring the construction of water connections and drainage inside them. Under these conditions, the network of channels became much more complex, and many ravines that had a specific role in the functioning of the deltaic system were annihilated—the Sulina and Sf. Gheorghe branches also underwent significant changes. The Sulina channel was shortened, in the period 1862–1902, from 91.9 km to 63.75 km and deepened as a result of creating a maritime waterway. The increase of the transited flows of water generated an erosion of the bed of the riverbed, thus increasing its depth. The Sf. Gheorghe branch was shortened, between 1985 and 1990, from 120 to 70 km, by cutting the meanders between Km 17 and 85. The Chilia branch increased from 113 km (1870) to 120 km (1985) by advancing the Delta of the same name from its mouth into the Black Sea. The total length of the natural and partially modified backwaters is

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about 1,742 km, and the channels are 1,753 km. Among the natural backwaters, backwaters with a total length of 285 km remained in operation, some remaining in the dammed enclosures (agricultural facilities Pardina, Sireasa, Murighiol-Dunav˘a¸t, etc.). The current network of channels dated mainly to the seventh decade when the issue of reed exploitation through landscaped enclosures was raised. Together with the natural backwaters, these channels represented the most efficient inland hydrographic network in 1960–1970 in water circulation and naval transport. Subsequently, by changing the direction of capitalization of some natural resources, many of the channels were abandoned, invaded by vegetation, clogged with alluvium. Between 1991–1994, the dam and the accompanying channel were built between Sulina and Sf. Gheorghe with some negative ecological consequences. The lakes constitute an important morpho-hydrographic category in the whole Danube Delta [12]. Even if through the works of arrangement of numerous precincts, many lakes and even lake complexes have been completely drained (agricultural arrangements Pardina, Sireasa) or partially. The inventory of lakes made before 1960 resulted in some 668 lakes totaling 31,262 ha (9.28% of the Danube Delta area). Following the drainage of the lakes from the most significant agricultural developments in the Danube Delta, Sireasa, and Pardina, their total number decreased to 479 (lakes larger than 1 ha), and the entire area reached 25,666 ha (7.82% from the delta surface) [13, 14]. The marshy lands are located between -0.5 and + 1.0 m altitude, and they occupy the areas around the lakes and the lake complexes from the depression areas. They are covered by water, depending on the level of the Danube and the marshy vegetation. Many of these lands were drained by the damming and the realization of agricultural and forestry arrangements. In fisheries, this morpho-hydrographic category has remained but is subject to the directed hydrological regime. The surface covered with aquatic vegetation is estimated at 143,500 ha (43% of the surface of the Delta). The Razim-Sinoie lake complex, with a total area of about 103,000 ha, consists mainly of lakes, sea ridges, and several higher relief formations that are evidence of erosion. The lakes occupy about 85% of the complex (86,300 ha) and are of lagoon type (Razim, 41,500 ha, Sinoie, 17,150 ha, Golovi¸ta, 11,870 ha, Zmeica, 5460 ha, Nunta¸si, 1,050 ha and Istria, 560 ha), limanic-type (Babadag, 2,370 ha, with T˘auc extensions, 180 ha, and Topraichioi, 50 ha, Agighiol, 490 ha, all transformed into fishing facilities) and lakes between the ridges (Leahova-Co¸sna-Peritea¸sca, 3,550 ha or those on the Chituc ridge, Edighiolurile, 1,070 ha) [15]. With a total area of 140,492 ha, the coastal maritime area stretches for 166 km, from the mouth of the Chilia channel in the north to Cape Midia in the south and has the appearance of a submerged plain with very few morphological irregularities. The continental shelf (width) has a width that decreases from north (170 km) to south (130 km). The value of the slope increases from the north (1°) to the south (2°) considered on the profiles oriented from west to east from the shore to the continental slope. The uniformity of the continental shelf relief is due to reduced Pleistocene modeling and intense sedimentation due to alluvium discharged by rivers northwest of the Black Sea and those brought by the Danube, and to a lesser extent to material

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from coastal area abrasion. Considering morphometric, morphological, sedimentary, and even biological criteria, the continental shelf (shelf, also called continental margin) can be divided, in the Romanian sector, into three compartments: internal shelf, medium shelf, and external shelf [11, 16–20]. The inland shelf runs from the seashore to the isobath of about 40–50 m and is the area on which the boundary of the Reserve stretches (isobath 20 m). The site is characterized by a plain of abrasion and accumulation resulting from variations in sea level during the Quaternary period, overlapped by landforms resulting from the subsequent deposition of fluvial sediments. This submerged space represents the field of action of the modeling factors, namely the waves and sea currents that process and transport the alluvial material. From a sedimentological and textural point of view, the sandy fraction predominates on the internal ridge, gradually passing towards the transition ridge in favor of silt [21]. The median shelf runs between the 40, 50, and 70 m isobaths, and the outer shelf runs between the 70 m and 130 m isobaths (according to other authors, 200 m). According to the 2011 census, the study area population was 183,822, 170,345 in Tulcea County, and 13,477 in Constant, a County. The number of inhabitants in Tulcea County decreased from 256,492 in 2002 to 201,462 in 2011, representing 21.5%. The study area’s population went from 219,227 to 183,822 inhabitants in the same period, losing about 16.3% of its population. As a benchmark, using the same data and for the same analysis period, Romania lost 11.05% of the population.

3 Methods The study results from the analysis of strategic documents developed by European, national, regional, county, and local authorities highlighted the opportunities and constraints for the development of the Danube Delta. At the European level, the Advisory Committee on Territorial Cohesion has developed a strategic framework that ensures better coherence of investment at the European level, called Integrated Territorial Investment (ITI). The consultation paper involves integrating development strategies from the European level to the local level, thus ensuring a common front in achieving the development objectives at the European level. According to the Advisory Committee, “In addition to investments that support a development strategy through an ITI, additional actions targeted at the same area may be funded through the priority axes of an operational program or operational programs that do not participate in ITI funding - however, recommends that sectoral investments be linked to and aligned with integrated territorial development strategies” [22]. The analysis aimed at extracting relevant information for the study area from the National Strategy for Sustainable Development, a strategic document by which Romania expressed its support for the 17 Sustainable Development Goals (SDGs) of the 2030 Agenda, adopted by the UN General Assembly Resolution A/RES/70/1. The central elements of the strategy are innovation, resilience, and confidence that “the

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state serves the needs of every citizen, in a fair, efficient way and a clean, balanced and integrated environment” [23–25]. Another analysis reporting document was Romania’s Territorial Development Strategy (Polycentric Romania 2035, Cohesion and Territorial Competitiveness, Development and Equal Opportunities for People) is, a strategic tool that sets Romania’s long-term development goals. Does the strategic planning tool provide answers to some questions [26]? • What are the measures and projects that contribute to increasing the capacity of the national territory to generate economic growth and, implicitly, to maintain and attract an innovative workforce? • Which areas at the territory level require specific interventions for capitalizing or protecting the natural and built capital? • How to ensure the balance between economic, environmental, and cultural policies to coherently plan the development process and preserve the identity of the national territory? The National Recovery and Resilience Program (PNRR) is the tool used by the EU Member States to overcome the supra systemic crisis caused by the COVID19 pandemic. This funding mechanism provides the Member States with a very good context for securing the financing of development projects and ensuring the complexity of territorial systems to deal with future crises. The Regional Operational Program South-East Development Region (ROP SE 2021–2027) aims to ensure the coherence of Romania’s strategic approach to regional development, linking regional priorities to national and European ones. The main objective of this regional intervention tool is to increase the economic competitiveness and improve the living conditions of local and regional communities by supporting the development of the business environment, infrastructure conditions, and services, which will ensure the sustainable development of the region, able to manage efficient resources, to capitalize on its potential for innovation and assimilation of technological progress. The contextualization of the research at the county level was achieved through the analysis of the Sustainable Development Strategy of Tulcea County 2021–2027, which in this reference interval proposes the following strategic objectives [27]: • Increasing the competitiveness and economic attractiveness of Tulcea County, both for current investors and for potential investors to develop innovative and value-added activities; • Creating a good quality transport and municipal infrastructure to increase the accessibility of the county and provide quality public services; • Ensuring adequate, coherent, and sustainable management of natural resources and natural and anthropic risks in Tulcea County; • Capitalizing on the special agricultural and fishing potential of the area by providing the infrastructure and the means to generate added value; • Increasing the quality of life of citizens and equal access to public services by providing educational services;

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• Sustainable, sustainable, and environmentally responsible development of county tourism, by capitalizing on all-natural and anthropic resources and practicing and promoting all possible types of tourism; • Ensuring good governance and strengthening the territorial cooperation relations of Tulcea County. Particular attention was paid to the Integrated Strategy for Sustainable Development of the Danube Delta approved by Government Decision no. 602/2016 [28]. The document aims at the sustainable development of the Danube Delta through a balance between the protection of natural heritage and socio-economic development, with the local population as a partner active in implementing the strategy [29].

4 Results According to the document Integrated Territorial Investments (ITI), the territorial development of geographical areas with a high specificity requires achieving a strategic framework with integrated development objectives and a coherent action plan with well-established budgets and implementation schedules. According to this document, the pillars established as development landmarks were: Pillar I: Protection of the environment and natural resources. The main comparative advantage of this region is the richness and diversity of the environment. Even if it imposes constraints on certain economic activities (which are not promoted in or near the Danube Delta Biosphere Reserve), this space offers significant opportunities to bring prosperity to the region, if adequately exploited, by generating as much income as possible. Possible on the responsible use of living natural resources and the preservation of specific cultural traditions. After a consistent period of transformation and exploitation as an agricultural area of the Danube Delta, the concept of re-naturalizing the area appeared. Even if the first measures consisted only in making some gaps in the dams of the agricultural enclosures, the natural ecological reconstruction could be observed. Subsequently, it was found that only the legislative measures adopted, and the natural re-natural capacity of the deltaic area are not sufficient. In the long run, sustainability will depend on local people who will play an active role as protectors and administrators of cultural and environmental assets in the Delta, in partnership with representatives of the Romanian state. The main challenges regarding the protection of the environment and biodiversity, which require better coordination between the different institutional actors with responsibilities in the field of their conservation, are: – the decline of some fish populations and the overall reduction of the diversity of the fishery resource (sturgeon, carp, pike, flax, crucian carp, etc.); – many buildings used as boarding houses or holiday homes in the Danube Delta do not have a building permit or are not authorized as dwellings. This is possible due to the lack of specific rules for the construction regime in this protected area;

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– insufficient and inefficient waste management; There is an increase in both the amount of waste generated by locals and tourists (especially the fact that the products used are predominantly outside the deltaic area), but especially the waste that reaches the Delta area and later in the Black Sea, through the Danube upstream; – the need for ecological reconstruction of areas used for agriculture, especially during the communist period. These consisted of the industrial exploitation of reeds, the construction of about 40,000 ha of fish farms (Popina, Chilia, Veche, Stipoc, Dunav˘at, , Holbina, Periteas, ca, Peris, or, Ceamurlia) and about 100,000 ha dammed for the organization of agricultural holdings, which have been largely abandoned for the past three decades. Pillar II: Improving the economy. The sustainable growth of the economic activity of this specific geographical area is the only possibility for its heritage to be preserved. The main comparative advantage of this region is the richness of the environment. Even if it imposes constraints on certain economic activities, it also offers significant opportunities to bring prosperity to the area, if adequately exploited, by generating income-based as much as possible on the responsible use of living natural resources and the preservation of local cultural traditions. Tourist activities adapted to the conditions of the reservation, sustainable exploitation of fish and reed resources, river transport activities, being the main income-generating activities. The economic activities carried out in this area have evolved with the national or European economic context. If, initially, the naval transport was the main activity generating essential benefits, it was also reported to the exploitation of other resources of the Delta. Industrial fishing, exploitation of raw materials for the paper or construction materials industry. Last but not least, agriculture was the predominant economic activity. Currently, the tourist activities register an increase of incomes, the investments being mainly private in this field. However, some weaknesses of the local tourism industry are identified as well: – significant problems in the area, which prevent some agencies from promoting Delta more, – such as poaching, waste, limited access, poor public service infrastructure, etc.; – tourism infrastructure and related services for underdeveloped visitors; – insufficient mobility between the localities in the center of the Delta; – lack of qualified staff in the hospitality industry; – last but not least, poor promotion, especially for foreign markets, lack of a tourism development strategy, and a brand manual. Agriculture and fish farming remained in the background, mainly due to declining fish stocks, rising fuel prices, poorly developed infrastructure (lack of irrigation/drainage systems), and a reduction in the workforce. One of the leading causes of the complex problems local agriculture faces is the lack of consolidated associative structures of farmers to compensate for the lack of financial, logistical, and technical resources, marketing and marketing, and reduced bargaining power. Large trade chains that bring goods from their countries of origin. No cluster structure

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has been developed in the agri-food sector, although both agriculture and the food industry provide over 50% of jobs in the area. Pillar III: Improving connectivity. An efficient transport system should primarily connect the Danube Delta area with the rest of Romania and neighboring countries. In this sense, it is a priority for the region to be connected to the corridor of the trans-European maritime networks TEN-T Rhine - the Danube by modernizing/rehabilitating the road Tulcea - Constant, a - Br˘aila - Galat, i, which is part of the central and global network of TEN-T. The region’s connection to the TEN-T network will increase the prospects for economic activity and open the way to southern Europe and Asia, namely Bulgaria, Turkey, Greece, and the Northeast, namely Ukraine, Moldova, Russia, Belarus. Modernizing these road routes is essential for proper traffic of goods and people and maritime transport. It would give more importance to the seaports of Constant, a, Br˘aila, Galat, i, Tulcea, and Sulina, which are part of the central and global network of ports. The development and modernization of the infrastructure of the “Danube Delta” Airport in Tulcea would facilitate the rapid movement of people and valuable or perishable goods and, thus, would lead to an increase in the traffic of goods and people to and from the study area. Tulcea Danube Delta Airport operates low-cost services, thus having high growth potential, especially the number of tourists coming to the area. The airport is classified under Code 3C and is intended for short and medium-haul courier services with a maximum of 48 CAN. The Danube Delta Airport has a 2,000 m long and 30 m wide concrete runway. It is necessary to develop the airport’s capacity by increasing the number of aircraft parking platforms, expanding the runway, developing the embarkation-disembarkation areas that will allow the operation of high-capacity transport aircraft. The modernization of the port of Tulcea (located between nautical miles (Mm) 34 - 42) is another direction in improving zonal connectivity. In the delta, port activities are also carried out in Sulina, Isaccea, M˘acin, Chilia Veche, Mahmudia, Smârdan, Hârs, ova and Gura Aman and Turcoaia, and the wharves from Cris, ani, Maliuc, Partizani, Gorgova and Babadag. However, Tulcea, Sulina, and the other ports inside the Delta require investments to transport goods and passengers to the current requirements. In general, investments are needed to increase the berthing function, the rehabilitation of the railways and roads that deserve the ports, the adaptation of the port infrastructure to the container transport—upgrading existing locations for small private and recreational vessels. At the same time, the maintenance of the Sulina Channel, which is maintained for maritime navigation, is a priority. This branch of the Danube takes up about 19% of the water volume. It has a length of 64 km, a maximum width of 250 m, a maximum depth of 18.0 m, and a minimum depth of 7.32 m. The rehabilitation of the banks is necessary to ensure navigation conditions and their protection against erosion.

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The level of performance of the road infrastructure must also be high to ensure the quality of travel and general transport. Disruption of traffic due to infrastructure degradation causes inconvenience, additional costs, and losses in terms of travel time and fuel consumption. Many of the roads located mainly in the localities inside the Delta do not have a road system; they are practically made of sand that cannot ensure smooth and safe traffic, especially during rainy periods. At the same time, the lack of road-related infrastructure, gutters for rainwater runoff, sidewalks for pedestrians, bike lanes make the current mobility a reduced one. Pillar IV: Providing public services. The physical and geographical conditions characteristic of the Delta makes the localities located at great distances one that generates an increased difficulty in ensuring the needs in terms of essential services. Water supply and sewerage, waste collection, access to quality education and health services, mobility during the cold season are not present in the whole area. Low population density and difficult territorial access make these services much more expensive than other parts of the country. At the same time, the lack of natural or human resources makes it challenging to develop this space. Given these restrictions, unconventional alternatives to service delivery need to be considered. For example, investments in improving network and information technology network connectivity can lead to distance learning and e-learning programs, legal and social assistance, and even medical services. Alternatives to providing preventive medical services, such as mobile medical units, are beneficial for medical services. However, the difficulty remains to ensure water supply, wastewater and waste collection, emergency medical services. Moreover, this area faces diffuse pollution generated by the site and the entire hydrographic area drained by the Danube River. The Commission Communication “EU Strategy for the Danube Region COM (2010) / 715” draws attention to the water needs of the Danube River, which are also relevant for the Danube Delta region. Nutrient pollution is caused by agriculture (both cultivated land—mineral fertilizers and animal manure—manure) and untreated water from factories and urban areas. This generates eutrophication and accelerates the growth of algae. Organic pollution is caused by pollution from point sources from the lack of domestic wastewater treatment in synthesis and industries and diffuse pollution from agricultural practices. Hazardous substances pollution: mainly caused by industrial waste, spills from mining operations, and accidental pollution. Hydro-morphological changes: caused by dams, dams, changes in the direction, and riverbed with effects on the rivers and the inhabitants of the area and the disconnection between the wetlands / adjacent floodplains. Saline intrusions: the high impact of saline intrusions and high sea level, specific to the deltaic space on inland waters. Risk of flooding: living in the floodplains of the Delta has always been a challenge and the optimal use of areas of natural expansion.

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Fig. 3 Natural parks and reservations, data source: © OpenStreetMap contributors, Ministry of Environment, Water and Forests

Ecosystem services: The Danube Delta has a high ecological value due to flora and fauna of the area (Fig. 3). The region is under the protection of Natura 2000 and RAMSAR. In addition to its environmental importance also has economic value (tourism, raw materials, fish farming, etc.) and heritage value. The Danube Delta has a sustainable system by self-sanitizing the water with the help of wetlands, breeding areas for birds and fish, etc. Water pollution and hydro-morphological changes harm the ecosystem (fauna, flora, sediment transport). Pillar V: Promoting efficiency, accessibility, and sustainability. The administrative policies applicable to this geographical area must be clearly defined and implemented uniformly and without syncope. Alternative solutions to local authorities (concessions, external institutions, etc.) are less accountable to the beneficiaries of these investments. Suppose neither households nor local authorities can support local services in the area. In that case, financial aid must be provided through specific subsidies from the central government, or services will need to be adjusted to a reasonable level. The capacity of local authorities and the capacity of all institutions to manage the type and level of projects needs to be strengthened. For example, the only Integrated Territorial Investment in the 2014–2020 programming period, according to the provisions of the Operational Programs, amounts to: e 1.114 billion of European funds, plus national funding [30].

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5 Conclusion The analysis of the integrated strategic development framework, as well as how it was implemented and is reflected in the action plan within the Integrated Strategy for Sustainable Development of the Danube Delta, leads to some conclusions: • The Danube Delta has been experiencing a sharp decline in population over the last 30 years. Development projects, which aimed to reduce this demographic decline, did not achieve their target, which shows errors in their substantiation. One of the most critical errors is underestimating the role of accessibility on the evolution of the number of inhabitants and the sustainable development of the local economies in the Danube Delta. Delaying the implementation of road accessibility projects to two important growth centers, Sulina and Chilia Veche, will lead to an increase in the depopulation process beyond the negative critical threshold. Demographic aging is a characteristic of all territorial systems in the Danube Delta, a process that will contribute to the demographic decline and the economic evolution of the studied area; • The delay in the implementation of the integrated development projects contributed to the accentuation of the migratory flows of the active population from the localities from the Danube Delta to the polarization centers Tulcea, Constant, a, Br˘aila, Galat, i, and Bucharest; • The depopulation of the localities in the Danube Delta has contributed over time to a decreasing capacity of the local economy to generate jobs, the accessibility component being defined in the evolution of this component of the territorial systems in the studied area; • The low number of project proposals for the development of the studied area results from a reduced institutional capacity to generate and implement projects. Thus, it is essential to adapt the administrative system to the needs of the citizens and the consistent possibilities of financing. There is also a need to implement a high-performance territorial management system based on the sustainable use of the vast resources available to the Danube Delta and the access of the population in this area to modern public services; • The inefficiency of the current management system requires a rethinking of the actors who must participate in the decision-making process, increasing the role of local communities being one of the necessary changes to increase the relevance of development strategies. • The National Recovery and Resilience Program (PNRR) was an excellent opportunity to fund significant projects for the development of the Danube Delta. Still, the number of projects proposed by the authorities is minimal and was not the result of stakeholder consultation, so the result was an inconsistent list of projects, many of which did not receive approval to be part of the final form of the PNRR. The results obtained can be supplemented in future research with information on the structural dynamics of territorial systems, information received through new working methodologies, fractal analysis being recommended to complete established

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methods, and which can permanently update the results that assist development decisions [13, 15, 24, 31–34].

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