Hydrography and Navigation on the Congo River: A Century of Visual History 3031410645, 9783031410642

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Paul Van Pul

Hydrography and Navigation on the Congo River A Century of Visual History

Hydrography and Navigation on the Congo River

A schematic overview of the different reaches of the Congo and Kasai rivers and their designations as used in this book

Paul Van Pul

Hydrography and Navigation on the Congo River A Century of Visual History

Paul Van Pul Saskatoon, SK, Canada

ISBN 978-3-031-41064-2 ISBN 978-3-031-41065-9 https://doi.org/10.1007/978-3-031-41065-9

(eBook)

© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 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. Cover illustration: An aerial view of the braided section of the Maritime Congo River, downstream from the city of Boma. It is an ever-changing landscape of erosion and accretion. (Source: J-J Peters Archive, Flanders Hydraulics, Antwerp) This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Paper in this product is recyclable.

Preface

The Congo River basin encompasses 4 million square kilometers [1,544,400 sq. mi], coming in second only to the Amazon River basin.1 Both regions harbor massive tropical forests, sometimes said to be the two lungs of our planet. While in recent decades the Amazon basin has been heavily exploited for its resources, the Congo basin is still mainly untouched and from a scientific point of view it is, to a large extend, unknown. Nevertheless, from the first half of the twentieth century, during Belgian colonial rule, a large body of scientific and applied science work exists. It appears that this research has largely been forgotten by the international community, in my opinion mainly since it was mostly written in French, and that the bulk of this research still resides in Belgian archives. With this book, I will try to lift one small corner of this impressive hidden collection of studies. In the first part of the book, I travel the thousands of kilometers of waterways of the High-Congo (in French Haut-Congo) that were once heavily used by indigenous travelers, European explorers and, still later, small, and large vessels, delivering passengers and goods throughout the Congo basin. The HighCongo is separated from the maritime section of the river by a massive and unique geographical feature: the unnavigable cataracts reach. In the second part of the book, I recall the early European forays into the maritime section of the Congo River, and in the third and last part, I concentrate on a century of hydrographic studies meant to better understand, interpret, and adapt the morphology of the maritime river with the aim to improve the navigability of the river so that Central Africa would retain direct access to the ocean and its worldwide trading partners. With this English-language story on a century of navigation and hydrography of the Congo River basin, I hope that future scientists, engineers, and many other interested people will get a taste of the immense potential that lies in the Democratic

1 For comparison, the Mississippi River basin comes in third place at 3.2 million km2 [1,245,000 sq. mi].

v

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Preface

Republic of the Congo, and that the basis for further nautical and hydrographic development is often hidden in Congolese or Belgian institutes. Today huge amounts of data can be collected through remote sensing, but to detect trends and try to predict future developments, one needs historic records for comparison. In the past century, most of the process of collecting data was slow and tedious work, often in a hazardous environment and under distressing climatological conditions. Saskatoon, SK, Canada

Paul Van Pul

About the Maps and Charts

All the maps and charts in this book have been drafted by the author himself. Since the end of the nineteenth century, thousands of maps of the Congo River have been drafted, some were sketches and some were incredibly detailed. Initially all were in black and white, except when they were hand-colored.2 Over the years, as techniques and instrumentation improved, their accuracy grew. The author’s aim was to produce a standard layout throughout the book, making it easier for the layperson and the expert alike to get a better grip on the essence of the drawings. For that reason, the choice of color for all the maps is identical. Green depicts the (dry) land areas as represented in the SVN map of the particular year. Islands are full green; the mainland is often a fading green. Sometimes, heavy vegetation is in a darker green. Historic trails are in a black dotted line, while modern day roadways, as a comparison with the past, are in red. Where they were available and could improve the visualization of the surroundings, contour lines have been included, with their elevation, but only in larger intervals, like every 50 m [164 ft] and only to give an impression of the lay of the land. Water, as can be expected, is in shades of blue: Atlantic Ocean, lakes, and rivers. Point features: Boulders emerging in the dry season are indicated by an asterisk. On the inland waterways, the author has often included a geographical coordinate point. This point is approximate and only as a general chart reference. Submerged rocks, a hazard to safe navigation, are indicated by a black cross in a white circle.

2

At Flanders Hydraulics in Antwerp, a (high resolution, digital) copy of most of these maps is archived. vii

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About the Maps and Charts

Linear features: Blue, dash-dotted lines are the current contours of a river, as opposed to the historic run of the river, while white dashed lines indicate the current shoreline as opposed to the historical shore. Country borders are in a dash-double-dotted magenta line on a white background. The navigation channel or fairway in the river is indicated by a magenta, dash-dotted line on a full-line, white background. As for the maps of the maritime section of the Congo River, the pattern is in general the same. However, since various depths needed to be represented, a few colors were added. The shoals and sandbars that surface in the low water season are yellow, while the riverbed up to 5.5 m depth (three fathoms) is of a salmon color.3 In later maps, based on metric measurements, cartographers replaced the 5.5 m [18 ft] contour with the 5 m [16.4 ft] contour. Light blue are the areas between 5.5 m (or 5 m) and 8 m and dark blue depicts the riverbed depth of at least 8 m. However, from 1954 on, with the growing size of vessels, the dark blue represents depths of over 10 m [33 ft]. As of then, lines of 8 m that might be important (i.e., indicating essential crossovers) are partially represented with a black line within the light blue. No cartographical distinction has been made between a tide or staff gauge, a marigraph or a limnimeter.

3

The local depths are referenced to the zero of the nearest limnimeter. As the surrounding terrain elevation increases, this zero has an increasing value in the national elevation map. So, while the terrain elevation might increase, the bathymetric measurements will always refer to the minimum local water level.

Acknowledgments

Without support from many, this work would not have been possible. In the first instance, I must thank Steven Cerpentier, Information Manager at Flanders Hydraulics in Antwerp, who provided me with tens of charts and hydraulic studies produced over the decades regarding the Congo River. I especially thank the Devroey family who allowed me free access to the archives of their grandfather, Chief-Engineer of the Colonies, Égide Devroey. His extensive body of articles, books, studies, and hundreds of photographs gave me a detailed look at the Congo River in the interbellum period. Evelyne Gilles and Anne Welschen at the Royal Museum of Central Africa in Tervuren provided me with pictures of early steamers on the HighCongo and access to the cartographic repository at the museum. Prof. W. Coudenys, expert on Russian emigration, introduced me to the surprisingly extensive Russian émigré society putting their technical skills to good use in the early years of the Belgian colonization of the Congo. Nautical journalist Georges Janssens in Antwerp dug up the history of various vessels, while Koen Vanstaen, Director of Flanders Hydrography in Ostende, and Sarah Schenk of the Flanders Maritime Service (Pilots Agency) provided additional details. Hydraulic engineers Stefaan Ides of the Port of Antwerp-Bruges and Phil Helwig (Helwig Hydrotechnique, St John’s, Canada) meticulously reviewed my manuscript and provided me with lots of technical and other very useful comments. My long-time friend and fellow author, Geography Professor Avi Akkerman, at the University of Saskatchewan, was always a sounding board and trustful advisor on the plentiful issues I encountered during my digital travels throughout Central Africa in the pandemic years. Finally, I want to thank my dear friend Bernard Duwez in Brussels, who provided me with photographs from his family archive, facilitated my interactions with always welcoming persons, and often acted as my local agent without whom my research in Belgium would have been a lot more complicated.

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Contents

Part I

General Hydrographic Description of the Haut-Congo Basin

1

Introduction to the General Geography of the DRC . . . . . . . . . . . .

3

2

Early Shipping on the Haut-Congo . . . . . . . . . . . . . . . . . . . . . . . . .

9

3

From the Source to Kisangani: The Upper-Congo . . . . . . . . . . . . . .

19

4

From Kisangani to Mbandaka: The High Middle-Congo and Ubangi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

29

5

The Low Middle-Congo: From Mbandaka to Tsumbiri . . . . . . . . .

35

6

The Last Stretch to Kinshasa: The Congo Couloir . . . . . . . . . . . . .

39

7

The Upper-Kasai Watershed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

43

8

The Sankuru, Fimi-Lukenie, and Lower-Kasai Tributaries . . . . . . 8.1 The Sankuru River System . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 The Fimi-Lukenie Watershed . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 The Lower-Kasai Tributaries . . . . . . . . . . . . . . . . . . . . . . . . .

. . . .

49 49 51 52

9

The Kwango and Kwilu Watersheds . . . . . . . . . . . . . . . . . . . . . . . . 9.1 The Kwango River System . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 The Kwilu River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

57 57 62

10

The Congo Cataracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

65

Part II

Early European Mapping of the Maritime Congo River

11

The First Europeans Venture Up the Congo Estuary . . . . . . . . . . . 11.1 Conquering the Cataracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

73 76

12

The Kouilou-Niari, an Alternative Access? . . . . . . . . . . . . . . . . . . .

81

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13

Contents

The Voyage from Europe to Congo . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 Belgium Takes Over the Congo . . . . . . . . . . . . . . . . . . . . . . . .

Part III

89 92

The Hydrography of the Maritime Congo River

14

Introduction to the Bas-Congo . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 14.1 Climatological Observations . . . . . . . . . . . . . . . . . . . . . . . . . . 95 14.2 Population of the Kongo-Central Province . . . . . . . . . . . . . . . . 96 14.3 The Top Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 14.4 Vegetation Along the Maritime Congo . . . . . . . . . . . . . . . . . . . 97 14.5 The Congo River Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

15

Early Maps of the Maritime River . . . . . . . . . . . . . . . . . . . . . . . . . 101 15.1 Physical Description of the “Divagante” Region . . . . . . . . . . . . 106 15.2 From Boma to Matadi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

16

The Acute Need for Bathymetric Surveys . . . . . . . . . . . . . . . . . . . . 115 16.1 The First Soundings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 16.2 Pierre Van Deuren . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

17

Hydrographic Basics in the Tropics . . . . . . . . . . . . . . . . . . . . . . . . 125 17.1 The Role of the Hydrographic Team . . . . . . . . . . . . . . . . . . . . 129 17.2 The Topographical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 134

18

A New Navigation Channel in the Making . . . . . . . . . . . . . . . . . . . 137 18.1 The Nisot and Mayaudon Passes . . . . . . . . . . . . . . . . . . . . . . . 137

19

The Mateba Deceiving Bend (Barrage du Faux-Bras de Mateba) . . . 147

20

Difficult Years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.1 Where Is the Border Exactly? . . . . . . . . . . . . . . . . . . . . . . . . . 20.2 The War Years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.3 Alexandr Khokhloff Returns . . . . . . . . . . . . . . . . . . . . . . . . . .

157 157 160 166

21

Independence in 1960 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.1 The Scale Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Nineteen Seventies, Ups and Downs . . . . . . . . . . . . . . . . . . . 21.3 About Dredging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

171 173 176 179

22

Based on Detailed Land Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

23

Epilogue: A Concept for the Future? . . . . . . . . . . . . . . . . . . . . . . . . 187

. . . .

Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix 1: A Brief History of the “Congolaise des Voies Maritimes” (CVM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix 2: Congo Waterways Interbellum Figures . . . . . . . . . . . . . . Selected Data on the Maritime Congo . . . . . . . . . . . . . . . . . . .

195 195 197 199

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

About the Author

Paul Van Pul (Antwerp, 1947) is a retired Belgian land surveyor and author, living in Canada. He specializes in the history of river engineering. This is his sixth book on the subject and the third in the English language. His first books investigated the First World War and how inundating large tracts of land were a military means to stop an advancing army. His most recent work delved into early hydroelectric dam building in the Canadian Prairies. The author loves drafting, so he always illustrates his text with many custom-made drawings, maps, and blueprints, which comes to light in this latest book where he tackles the history of navigation and hydrography in the Congo River basin, a vast region that was once a Belgian colony. He hopes this historical and nautical glimpse into Central Africa will entice a lot of young people, scientists, engineers, and ordinary readers around the globe to explore further what is in all aspects potentially the most promising region of Africa.

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Abbreviations

ANG CAR CBMC CFS cfs COG CSD CVM D/S DRC IRCB MHB MRAC RVM SHS ST SVN

TSHD U/S UMHK ZAM

Republic of Angola Central African Republic Compagnie Belge Maritime du Congo (1895–1930) afterward Compagnie Maritime Belge. Forerunner of this last one Congo Free State (until 1908) cubic feet per second Congo-Brazzaville Cutter Suction Dredger Congolaise des Voies Maritimes. Current designation of the Public Department looking after the Maritime Congo River Downstream Democratic Republic of the Congo Royal Institute of the Belgian Congo Missions Hydrographiques Belge. Belgian technical missions, assisting Congolese authorities after the independence of the country Royal Museum of Central Africa (Tervuren, Belgium) Régie des Voies Maritimes. Colonial department looking after the Maritime Congo River Service Spécial Hydrographique US Short ton Service des Voies Navigables. Public Department looking after all navigable waterways in the Congo in colonial times and shortly after independence Trailing Suction Hopper Dredger Upstream Union Minière du Haut-Katanga. Mining Union of Upper-Katanga Zambia

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Part I

General Hydrographic Description of the Haut-Congo Basin

Chapter 1

Introduction to the General Geography of the DRC

Abstract This chapter provides an overview of the main geographical features of the DRC, especially pertaining to its position within the neighboring countries. The typical Central African washbasin relief dictated by the Congo River watershed dominates the geography. The chapter also looks at the main regions within the borders of the DRC, unrelated to any political boundaries and lastly the principal vegetation zones, the result of the climate and their interaction with the hydrology of the Congo River watershed. Keywords DRC neighboring countries · DRC elevations · DRC regions · DRC vegetation The Democratic Republic of the Congo, in Central Africa, is a vast and rich country. At 2,345,409 km2 [905,567 sq mi] it is as large as the United States of America’s two largest states, Alaska and Texas, combined1 and it has an estimated population of 102 million. For such a vast country it has a coastline—at the Atlantic Coast—of only 35 km [22 mi], not considering half the width of the mouth of the Congo River and an island, Bulabemba, in it. That is less coastline than its once colonial ruler, tiny Belgium, has (Fig. 1.1). Due to the shape of its curving course, the mighty Congo River is unique in the world: it crosses the equator twice. Not only that, but it also has major tributaries in the southern as well in the northern hemispheres. That “divided” basin network creates two wet and two dry seasons in the river’s discharge. The Congo is a river of superlatives: it is the second longest (4374 km, 2718 mi) river in Africa (after the Nile), with the second largest basin (4,014,000 km2, 1,549,800 sq mi) in the world2 and the second largest discharge in the world—

1

For a Canadian audience, the DRC is larger than British Columbia, Alberta, and Saskatchewan combined. For Europeans, the DRC is 76 times larger than Belgium. 2 Figures for the drainage basin of the river vary between 3,6 million and 4,1 million km2 [1,390,000 & 1,583,000 sq mi] depending apparently on which areas previous authors did include or not. In comparison the Mississippi River has a basin area of almost 3 million km2 [1,158,300 sq mi] and Western Europe’s largest basin, that of the Danube, is only 801,500 km2 [309,460 sq mi]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_1

3

4

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Introduction to the General Geography of the DRC

Fig. 1.1 Neighboring countries of the Democratic Republic of the Congo

between a minimum of 23,000 and a maximum of 80,000 m3/s—after the Amazon River.3 Nevertheless, outside the French-speaking world, not much seems to be known about the navigational history of this noble river and its immense possibilities for the future (Fig. 1.2).

3

The average discharge per second of the Congo River near Boma (43,000 m3/s or 1,518,500 cfs) is about seven times the volume that flows over Niagara Falls, both sides, every second (5796 m3/s or 204,680 cfs).

1

Introduction to the General Geography of the DRC

5

Fig. 1.2 Elevations in the DRC

The geographic relief of the Democratic Republic of the Congo is often compared to a washbowl (Cuvette Centrale): the border regions are higher than the central part which is practically level. The edge of the flat part of the plate can be considered the contour line of 500 m [1640 ft] above sea level. The average altitude within is 400 m [1312 ft] with the low spot of 340 m [1115 ft] in the region of the Mai-Ndombe and Ntomba lakes in the west of the country. The highest elevations in the country can be found along the eastern border of the DRC with the mountain range along the West African Rift Valley and are formed, from south to north, by the Mitumba Range, the Virunga, Ruwenzori Mountains, and the Blue Mountains along Lake Albert. The highest peak of the Ruwenzori reaches 5109 m [16,762 ft], and the range's upper regions are permanently snow-capped and glaciated. Rivers fed by mountain streams form one of the sources of the Nile: because of this, European explorers linked the Ruwenzori with the legendary Mountains of the Moon, claimed by the Greek scholar Ptolemy as the source of the Nile. In the north, the Congo basin is only separated from the Nile and Chad basins by a camber plateau with a watershed height of between 700 and 800 m [2300 & 2625 ft]. The border of the country lies south of the watershed and is formed by the Bomu and Ubangi rivers. To the west the Congo is cut-off from various smaller river basins that drain toward the Atlantic Ocean since they originate on the western slopes of the

6

1

Introduction to the General Geography of the DRC

Fig. 1.3 Throughout its recorded history, that is during the European exploration, the Congo Free State, colonial rule and after independence, the administrative division of the DRC has often changed, together with the official naming of these entities. This evolution could be the subject of a book on its own. We will limit ourselves to locating the major regions of the country

bulge formed by the Crystal Mountain Range that follows the West-African seaboard. Here the mountains have rounded peaks between 350 and 500 m [1150 & 1640 ft]. In the south of the DRC, the Congo River drains a portion of the higher Lunda plateau in Angola that forms the divide between the Congo basin in the north and the Zambezi River system to the southeast (Fig. 1.3). The mineral-rich, southeast region of the DRC is known as Katanga.4 Its eastern flank has elevations of 1600 m, with peaks of 2000 m. As the elevations drop westward, shrub savanna dominates the landscape. To the northwest of Katanga lies Kasai, named after the second most important river of the country. Further west again is the Kwango region, named after the river with the same name that empties

4

Under the rule of President Sese Seko Mobutu the province was called Shaba.

1

Introduction to the General Geography of the DRC

7

into the Kasai River, close to its mouth. Elevations are between 750 and 800 m. All rivers flow from south to north and create a very picturesque landscape. Back in the east of the DRC, above Katanga, we find the Kivu Region, named after the lake with the same name, a part of the Albertine Rift. The higher elevations of the area have a lush, colorful Alpine vegetation. Unfortunately, up to this day, Kivu’s history has often been written in blood. West of the Kivu region we find the region of Bandundu. It is named after the city with the same name, located at the confluence of the Kwango and Kwilu rivers, just short of the confluence of both with the Lower Kasai. Under colonial rule, Bandundu was known as Banningville.5 North of Bandundu lies the Equatorial Region, dominated by the tropical forest and above it, between the Congo and Ubangi rivers, the Ubangi6 Region. The northeast region of the DRC is known as the Uele Region, after the Uele River that flows through it. Here, in the northeast a few mountain peaks reach 3000 m [9840 ft], but an average elevation is 1800 m [5900 ft], slowly dropping off to the cuvette centrale.7 The last region to mention is the Bas-Congo. It is the only Congolese territory that borders the Atlantic Ocean and encompasses the Cataract Region and the Maritime Congo River. It is this last region that we will look at in more detail in the second and the third part of this book. Constant tropical temperatures and daily afternoon rains between 4 °N and 4 °S make for a lush, eternal green, and dense woodland in the northern half of the DRC: the “Equatorial Forest”. The tallest trees reach 40 m [130 ft], and smaller ones grow underneath and form a second canopy. Then there is a third and sometimes a fourth canopy. The forest floor has equally dense vegetation, all sprouting out of a wet, fertile soil covered in a thick layer of decaying plant matter. Where swamps, due to the regular flooding of the rivers, persist, the plant diversity shrinks, and a swamp forest has developed. Along the riverbanks, outside the equatorial forest, soil moisture allows a continuation of the equatorial forest, in the form of gallery forests. They range farther north and south, into the extended savanna regions even into the southeast of the country. Where forest has been cut or burned for agricultural use and later abandoned, a secondary forest established itself, but unfortunately less diverse and less tall. In the Bas-Congo, along the Shiloango basin, north of the Congo River, exists the less dense Mayumbe Forest. Although the region sees a five-month dry season, since it is close to the ocean, westerly winds bring frequent mist and light drizzle that allow the forest to exist. Going further north or south than 4° the climate changes, and with it the landscape. The year now has four seasons: a long and a short dry season, each

5

At Bandundu, in 1937 and 1939, the Kwango had a recorded discharge of between 5817 and 2367 m3/s [205,425 & 83,590 cfs]. 6 In Congo-Brazzaville, the Ubangi River is called: Oubangui. 7 The cuvette centrale is the central plateau region of the DRC, having an elevation between 400 and 500 m [1300 & 1640 ft].

8

1

Introduction to the General Geography of the DRC

Fig. 1.4 Vegetation types throughout the DRC

time separated by a rainy season. It is a sub-equatorial climate, and the landscape becomes a wood savanna. Trees are shorter, only 20 m [65 ft] high, and they alternate with tall bush. The more we leave the equator behind, the more grassland appears in the mix. Only a small zone along the northern border of the DRC has wood savanna. Most of the wood savanna lies south of the Lukenie River. It stretches up to ten degrees south, except for the southeastern corner of the country, the south of Katanga, which falls within the shrub savanna. Here a tropical climate that has only two seasons dominates: a dry and a wet one. Trees and bushes become scarcer; grasslands rule the landscape. The trees have adapted to the dry conditions: trunks are gnarly with a thick, corky bark. This is the territory of the shrub savanna. Since the terrain is slowly rising as we have left the cuvette centrale, another savanna emerges: the montane or high plateau savanna. It is present in isolated areas of higher Katanga and along the Great Rift lakes. Only in local depressions shrubs will thrive but on the high grounds only some tough grasses survive (Fig. 1.4).

Chapter 2

Early Shipping on the Haut-Congo

Abstract This chapter deals with the multitude of hazards of navigation on the Congolese waterways in colonial times. In 1898 European engineers and Black labourers had managed to bypass the cataract region by building a narrow-gauge railway. Quickly a mixture of small private, religious, and commercial steamers plied the tropical rivers, hindering government regulated expansion. We then look at the various efforts by the Belgian colonial administration to organize this quickly expanding waterway traffic. After a look at the versatile Délivrance type of packet boat we follow the technical move to a system of “tandem towing” instead of lashed together barges. Keywords Shipping DR Congo · Pechuël-Loesche · Hydraulic gradient · Whaleboat · Devroey E · Packet boat Until the advent of a few railway lines into the interior of the Congo, the rivers in the tropical forest were the sole arteries of communication, but shipping in the age of steam on winding waterways in the equatorial forest and through the gallery forests could be fraught with dangers. Especially tree trunks and heavy branches that fell from overhanging canopies lurked under the waterline and formed a major hazard for small steamers. These dangerous obstacles, called “snags”,1 could easily pierce a hull, sink the vessel in minutes and could be a death sentence for the passengers and crew. Since most of the time the skipper’s view of the river ahead was restricted, snags could appear and hit the hull at a moment’s notice. The narrower the river got, the more overhanging trees became an additional hazard. Combined with a shallow channel that had to be followed, advance could be slowed down considerably. Keeping a schedule was out of the question.

1

Snag: an underwater object, like a fallen tree stump, which causes a hazard to shipping. Steamboat crews in North America classified them as, “Sawyers” would swing back and forth with the flow, “preachers” would nod up and down in the water, “planters” were tree trunks lodged in the riverbed and “sleepers” would float just under the waterline (After J. Anfinson, The River we have wrought, p. 9). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_2

9

10

2

Early Shipping on the Haut-Congo

In the early days of the CFS, before the railway from Matadi to Kinshasa was inaugurated (1898), getting a river steamer up to the Haut-Congo was a challenge of the greatest order. It might suffice to describe the journey of the seventh steamer launched in 1887 into what was then called the Stanley Pool at Kinshasa. The vessel, named Stanley, was designed, and built in England with the view of overland transport, to avoid the cataract region. The hull was formed by six, square-shaped, individual pontoons of galvanized steel, watertight, and buoyant that could be joined and taken apart quickly. To make the hull streamlined, a bow and stern section completed the assembly. Altogether, the hull was 21 m [69 t] long and 5.5 m [18 ft] wide. The boilers would drive a stern paddle and were equipped with grates to allow the burning of wood, obviously a readily available fuel along the Congolese forests. To protect against the tropical sun, the entire boat was covered with a roof, leaving the sides open to let the air flow freely through. After a test in Europe, the steamer was disassembled and shipped to the Congo. At the foot of the cataracts, each section and the boilers were transformed into a wagon to be pulled by native people along the caravan trail upstream. The German geographer Pechuël-Loesche:2 The type of steamer to be launched on the Haut-Congo is estimated to have a load capacity of 20 tons, if possible, better 25 tons. Accordingly, that would be equal to 600 to 750 porter loads (of 33 kg/person). Draught would have to be 75 to maximum 90 centimeters with a flat bottom. For fuel, firewood would be essential as it can be cut almost anywhere along the shore. It must be expected that a round trip on the inland rivers, including port calls and the frequent stops for wood collection, would take a month. Taking along a barge or two might be necessary but would not be essential. A fleet of small steamers could do the same job, but would be more expensive to acquire, run and maintain.

Pechuël-Loesche had the following, further recommendations on the construction of the steamers: It should be paddle steamers with paddles of reputable origin that are easily interchangeable. For that reason, spare paddles should be kept in storage. They should be rated for 50 RPM, giving the steamer a speed of 10 knots [18 km/h]. The paddles should be coupled so they can be driven independently.3 The machinery should be powerful but also simple, small, and parts should be exchangeable with those of other steamers. Condensers need to be uncommonly large to provide quick and full condensing, considering that the river water has already a temperature of 25 to 27.5°C. Practical considerations: the steamer must have enough open space. No European can handle being close to a boiler on top of the tropical heat without becoming incapacitated for work [dienstunfähig]. The boiler man needs to be able to work on deck, so he gets enough fresh air. On the same ground, shelter for the passengers should be in the bow, not at the stern

2

In 1872 the German geologist and explorer, Dr. Paul Güssfeldt, was chosen by the Deutsche Afrikanische Gesellschaft as the leader of a scientific expedition to the Loango Coast, just north of the Congo estuary. It became known as the Loango Expedition and took place between 1873 and 1875. One of the participants was the geologist Dr. Pechuël-Loesche, later appointed by King Leopold II to explore the Congo River. He was soon relieved of this task due to apparent indecisiveness. His theoretical specifications for steamers nevertheless were not far off the mark. 3 On the Haut-Congo, instead of paddle steamers, sternwheelers would be used as they were simpler to build, maintain, and were more adapted to manoeuvre on narrow and winding river channels.

2

Early Shipping on the Haut-Congo

11

Fig. 2.1 The hydraulic gradient of the Congo River and a few of its major tributaries of the vessel. To have the best overview, the wheelhouse too needs to be in the front part of the ship. The rudder needs to react swiftly to commands and be well secured to the hull to not get easily damaged when running into shallows. A sunroof needs to cover the entire deck. On the forecastle it should be in galvanised, corrugated iron or light wood. All outward parts should be painted light grey, to improve the reflection of the sun.

In 1871, Dr. Livingstone, on his epic journey through the interior of Central Africa, reached a mighty river, flowing northward, and called by the native peoples “Lualaba.” It was at a settlement called Nyangwe, between nowadays Kibombo and Kasongo (Fig. 2.1).4 The end of the nineteenth century was the time of the great explorations of Africa, especially the search for the source of the Nile. The dispatches of the explorers did sell newspapers in Victorian Britain and the United States. Four months after Livingstone saw the Lualaba River, Henry Morton Stanley met the good Scottish doctor in Ujiji, on the east bank of Lake Tanganyika. Since Stanley’s dispatches had mesmerized millions of readers, newspapers were more than willing to finance another expedition by the journalist, a new attempt to find the source of the Nile. Logic dictated that the Lualaba River, running north, was quite a potential tributary of the Nile. Therefore, Stanley returned to Zanzibar, on the east coast of Africa and, with a caravan of porters and three other white people, retraced Livingstone’s voyage toward Nyangwe and the Lualaba River. Using sectional boats and pirogues, his party descended the Lualaba and found out that the river did not continue to flow northwards, but instead turned west and eventually south again. This had to be the Congo River, not the Nile! Further descending the river and braving the cataracts reach, 2 years and almost 9 months after his departure from Zanzibar, on the 9th of August 1877, Stanley and what was left of his party, finally reached Boma, the major white trading post on the Maritime Congo River. Exploration of the Congo River from the west had up to then been blocked by the cataracts, upstream of the post of Vivi, almost across from what was to become 4

See the map of the Upper-Congo and Lomami watersheds for the locations.

12

2 Early Shipping on the Haut-Congo

Matadi. But now, Stanley had shown that, once past the cataracts, the interior of Central Africa was a lot more accessible than via the east. To explore the many rivers and lands in the interior, the Europeans would need motorized transport to travel upstream from the Malebo Pool. From Stanley’s voyage, they knew that the rivers in the interior were not deep, so the boats needed to have a shallow draught. The solution would lay in the use of small paddle steamers, either with side wheels or a stern wheel. The biggest hurdle was to get the steamers past the cataracts. Before the railway Matadi-Kinshasa became operational (in 1898), the first steamboats, the En Avant and the Royal, arrived at Banana in 1879, in sections in the cargo hold of oceangoing vessels coming from Europe. Here these small boats were assembled and under their own power steamed up the Maritime Congo to Vivi where they were partly disassembled. Via a newly constructed wagon trail the steamer parts were then pulled by black porters past the first rapids to Isangila. After a lot of toils, the vessels could be launched again on the intermediate stretch of river, up to Manyanga from where they again were pulled across the land. Finally, in December 1881 the first steamers could be launched on the Malebo Pool. In that laborious manner, 44 steamers were brought from Vivi to the Malebo Pool, then known as Stanley Pool, before the inauguration of the narrow-gauge railway from Matadi to Kinshasa. Early European shipping on the Haut-Congo came with a range of problems. It was established that the water level on the Congolese waterways had a range difference of between 3 and 6 m, and that twice a year. The reason for this was the fact that the wet season south of the equator alternates with the wet season north of it. A unique phenomenon, only known in Central Africa, as the Congo River crosses the equator twice. As Pechuël-Loesche described: The scene of the river during those periods is quite different. While the rapids or the few low waterfalls are quite present in the dry season, they completely disappear in the rainy season. Landmarks or cliffs stand high and dry or are completely flooded. The shoreline with its protruding rocks, rocky islands with stone masses, forested islands and shifting shallows are quite visible or deceivingly concealed by the heavy, loam-coloured waters. In the wet season, only in a few, unimportant spots the flow follows the general direction of the river. Everywhere else the stream gets slowed down, diverted, and broken up by the countless, invisible obstacles on the riverbed or along the shore. Counterflows, ripples and eddies are rapidly formed and just as quickly change direction or location, thereby moving as well downstream as upstream ...

Against all these wild, fluid situations, the little steamers of the first days had to fight their way through and stay the course. Those that had to rely on tiny screws for propulsion, even twin-screw boat, like the Belgique, were unreliable. The small boilers could never provide the necessary power, they were often overworked and were kept on too high a boiler pressure, resulting in time-consuming and improvised, on-the-fly repairs, not to speak of the myriad of dangers when power was lost in raging mid-stream. Those kinds of flimsy steamers were unsuited for the rigors of the Congolese waterways and would only last 3 or 4 years. On top of it, their small size

2

Early Shipping on the Haut-Congo

13

Fig. 2.2 A whaler somewhere on the Congo waterways, powered by manual labor. Notice the raised bow and in the stern the helmsman standing upright to operate the rudder. (HP.1961.5.418, collection MRAC Tervuren; photographe non identifié, s.d. Tous droits réservés)

meant that, when they were operational, they were constantly on the move to transport the tiny amounts of goods they could carry. Of course, a sturdier built, and larger paddle steamer would be more expensive to acquire, but would last at least a decade, carry more cargo, withstand the harshness of flood season, and need the same amount of crew to operate (Fig. 2.2). A motorized whaler or whaleboat was the smallest of vessels that would operate and carry goods and passengers in Congo. These boats had nothing to do with whaling,5 but being narrow with a pointed bow and stern they resembled the whaleboat as used in the whaling industry at the time. Their advantage was that, having a flat bottom, they could be beached anywhere and did not have to be turned around to refloat, an advantage if you happened to encounter not so friendly creatures onshore. According to Devroey the “Congolese” 5-ton whalers were 8.5 m long, 1.2 m wide, 0.75 m deep [28 × 4 × 2.5 ft], and had a draught of only 40 cm [1.3 ft]. As for the cargo they could take in Central Africa, I use a quote from Dr. J. Decorse.6 He and his companions had traveled upstream the Congo River

5 So-called “whaleboats” were often carried on warships and used to shuttle between the vessel and shore when in port. For that purpose, Royal Navy ships would carry 8.2 m [27 ft] whalers, hanging from davits. 6 1906: Du Congo au Lac Tshad. La brousse telle qu’elle est, les gens tels qu’ils sont. Carnet de route.

14

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Early Shipping on the Haut-Congo

from Brazzaville in the little steamer En Avant7 up to Oubangui from where they planned to continue their journey upstream, through the rapids. Later, he called the boat a whaleboat. “We all cram into a boat that then takes to the water: four Europeans, seven boys, twenty-two paddlers and two tons of luggage.” The number of vessels on the Haut-Congo grew steadily. As an example, by the end of 1937 a total of 1,313 units floating were registered, including 609 barges and 74 tugboats. At that time the favored propulsion system was, due to its robustness, simplicity, and economics, still the steam engine, running on locally cut lumber. Any threat of deforestation in the tropical forest was far from becoming a reality yet. Besides the government fleet [marine de l’ État], up to the end of the First World War, many commercial companies and religious missions ran their own vessels on the Congolese river system. One of the commercial companies, Citas,8 started an express river transport service in 1907. With the traffic on the river ever increasing, in 1919 the colonial government reorganized its fleet into a cooperative, called Sonatra which in 1925 absorbed the ever-growing Citas fleet. It resulted in a new, limited liability company called Unatra. The government retained control over tariffs and imposed a systematic organization of the inland waterways with regular connections to the main Congo and Kasai corridors. To further manage the growing transportation network and to gear the different transportation modes to one another, especially rail and waterway, the government in 1935 created an overall agency, called Otraco.9 A year later the waterway branch of Otraco took over the Unatra activities and its entire fleet, with a capacity, at the time, of 42,730 tons. During the First World War export of tropical goods soared and skippers started to tow barges alongside to increase freight capacity. Quickly it was realized that separation of propulsion from cargo was more advantageous. “Vessels lashed together” or “towing alongside,” were difficult to maneuver, suffered extra damage when accidentally grounded and considerably increased hydraulic drag. Although many steamboat captains disapproved of a change in towing procedures, trials went ahead anyway in 1922 with tandem tows10 on the main freight corridor, Kinshasa to Mbandaka.11 The trials found many advantages to “tandem towing.” On top of it a En Avant, a small paddle steamer, 13 m [42.6 ft] long with a draught of only 28 cm – not one foot. Citas: Compagnie Industrielle et de Transports au Stanley-Pool. Sonatra: Société Nationale des transports Fluviaux au Congo. Unatra: Union Nationale des Transports Fluviaux au Congo. 9 Otraco : Office d’Exploitation des Transports Coloniaux. The Office for Colonial Transport Management. 10 Tandem tows, as opposed to “towing alongside,” consists of a tugboat pulling one or more barges, one after the other, in a single row behind the tug. This was common on European inland waterways at the time. Another method, called “pushing ahead” was already practiced on the Mississippi River by specialized pushers. More towing information can be found in “Tugs and Tows - A Practical Safety & Operational Guide” published by www. shipownersclub.com. 11 In colonial times Mbandaka was known as Coquilhatville, after Camille Coquilhat (1853–1891). 7 8

2

Early Shipping on the Haut-Congo

15

scientific comparison between “tandem towing” versus “towing alongside” revealed that the latter required almost double the power as an equivalent tandem tow. This change in operation eventually allowed one tugboat to pull seven barges, sometimes even more. Smart organization of the tow also facilitated the drop-off and pick-up of barges at waystations. The rearmost barge could easily be dropped off at the first port of call and be recovered on the return voyage. In the meantime, the cargo could be unloaded and replaced by an outbound one. Overall, freight handling improved, and cost went down. From 1935 push tugs also appeared. They proved to be beneficial on the Upper Kasai, the Lulua, and other tributaries where, due to the sinuosity of the riverbed, towed convoys were impossible to control. By pushing two or three 40-ton lighters by a small, 40-ton motorboat to which two other 40-ton barges12 were lashed, a still economical, 180-to-220-ton combination could be put together. Once the Matadi-Kinshasa railway was inaugurated in 1898, bringing disassembled steamers to the Malebo Pool was of course a lot less laborious (Fig. 2.3).

Fig. 2.3 Délivrance V, moored at an outpost. Notice the wood, stacked high in the bow, ready to be fed in the boiler right behind. Whites would travel on the upper deck, away from the heat of the boiler. Rigidity of the light superstructure was achieved by means of cross bracing with turnbuckles. (HP.2010.8.1100, collection MRAC Tervuren ; photographe non identifié, s.d. Tous droits réservés)

12

For technical details on the different barges and tonnage, see Appendix 2.

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Early Shipping on the Haut-Congo

Table 2.1 General classification of the navigable waterways and their draught in the Belgian Congo Category First class Second class

Wet season 2.00 m 1.50 m

Dry season 1.30 m 1.00 m

Third class Fourth class

1.20 m –

80 cm 60 cm

Accessible to 800- and 1,200-ton barges 150- and 350-ton barges or 500-ton barges when river bends allowed 40-ton barge Only whaleboats

Up from the whaleboat were the Délivrances or packet boats. Over a period, six such steamers served on the Upper Congo waterways: the first was launched in September 1896, the last one in May 1902. Each of these steamers had an approximate gross weight of 20 tons. One or more barges could be lashed to them to transport goods and passengers (Table 2.1).13 Accessibility was understood to be shipping with a full load for 4 months (wet season) of the year and year-round not below a half load. Even a general description of the major rivers in the Haut-Congo basin cannot be given without maps. To keep a logical arrangement, the author subdivided the Congo basin into four main maps. The first map, in the east of the DRC, is formed by the Upper-Congo basin, including the Lomami River. It also includes Lake Tanganyika. This part ends at the confluence of the Lomami River with the Congo, downstream from the city of Kisangani. The second map involves the Middle-Congo and Ubangi systems. It is in essence the northern part of the DRC, the southern part of the Central African Republic, and the northern part of Congo-Brazzaville. The third section is west of the first map and comprises the Kasai River basin, including the Ruki-Tshuapa basins. It starts at the confluence of the Ruki14 with the Congo River at the City of Mbandaka. For easy reference, it can be called the southern map. The fourth map covers the Cataract region, downstream from Kinshasa. It is the smallest area and is situated to the west of the three other maps. It is not a part of the Haut-Congo (Fig. 2.4).

13

The Délivrance 6 sank and turned upside down on July 27, 1938, on the Kasai River, while in tow through a violent and turbulent section of the river, without loss of life. [Email by Georges Janssens, March 26, 2021.] 14 The Ruki basin covers 167,750 km2 [64,769 sq mi].

2

Early Shipping on the Haut-Congo

Fig. 2.4 The DRC main watersheds and map subdivision

17

Chapter 3

From the Source to Kisangani: The Upper-Congo

Abstract In seven chapters we take a closer look at the intricate river system in the Higher-Congo River basin. We start off with the rivers in the Upper-Congo basin, here also called the Lualaba River and the adjacent Lomami River. The source of the Lualaba is in the SE of the DRC where the border with Zambia is formed by the Zambezi and Congo watersheds. We follow the Lualaba, its navigable and unnavigable reaches and the man-made reservoirs that provide electricity for the industries in Katanga. Major tributaries like the Lukuga—the overflow for Lake Tanganyika—the Lufira and the Luvua are partly navigable also. The Lomami parallels the Lualaba but has a much smaller basin. Keywords Lualaba · Upper-Congo · Lufira · Lukuga · Lomami · Kisangani · Bukama We start in the southeast of the country. The source of the Congo River is the head of the Lualaba River, near Mumena in Katanga, some 120 km [75 mi] west of Lubumbashi, near boundary-stone No. 32 with Zambia, close to 11°56′ S and 26°30′ E, at an altitude of 1420 m. The border between the DRC and Zambia is delineated by the watershed of the Congo and Zambezi River basins. Since there are no discernable, geographical features that indicate the watershed, in 1911–1914 and again in 1930, a mixed Belgian-British survey mission determined the border between both countries with numbered, concrete pyramids, 1.40 m [4.6 ft] high, at about 5 km [3 mi] intervals with smaller, secondary markers in between. From its source, the Lualaba winds its way between the Sakabinda mountains and the Manika plateau, through the Nzilo gorge. Here the Lualaba descends 450 m over only 70 km [1476 ft. over 43.5 mi]. Since 1953 a 20-m-high [65.6 ft] dam retains Lake Nzilo and 4 × 25 MW turbines provide electricity to the national grid (discharge is between 28 and 305 m3/s [990 & 10,770 cfs] with an annual average 100 m3/s). The Nzilo catch basin covers 17,000 km2 [6564 sq mi] (Fig. 3.1). The river then enters the Kamolondo depression and 20 km [12 mi] downstream— as the crow flies—another hydropower dam diverts water to the Lufupa River, a stream that joins the Congo near Busanga. Six hundred and sixty-six kilometers © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_3

19

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From the Source to Kisangani: The Upper-Congo

Fig. 3.1 Map of the Upper-Congo with main tributaries and selected, secondary basins

3

From the Source to Kisangani: The Upper-Congo

21

Fig. 3.2 The railway bridge at Bukama, shortly after its opening. It is a so-called Vierendeel Truss Bridge, named after its inventor, Belgian professor, and civil engineer Arthur Vierendeel. Most of these types of bridges can be found in Belgium. (Photo courtesy Devroey Family Archive)

[413 mi] from its source, the Congo passes through the city of Bukama. At Bukama, a 248 m [813 ft] long railroad bridge, built in 1928, carries the Lubumbashi to Kamina and Ilebo1 Railway across the river (Fig. 3.2). From here the Upper Congo River is navigable for 640 km [398 mi] by vessels of 150 tons, to the city of Kongolo, where the “Gates to Hell” (Portes de l’Enfer) block any further shipping. At flood level, barges with a draught of 1–1.5 m [3.3–5 ft] can travel this section, except from Kiabo Head to Bukama (94 km, 58 mi) where in the dry season only 80 cm is available.2 It is the first—and upper—navigable reach of the river. From Bukama on, and for 250 km [155 mi], the river forms an inland delta, winding its way through the Kamolondo Plain, a marshy, 45–50 km [28–31 mi] wide region with numerous lakes.3 At 500 km2 [193 sq mi], the largest of the lakes is Lake Upemba that gave its name to the Upemba National Park, established in 1939. Only one lake, Kisale, is traversed by the Congo River. At flood stage, the river deposits copious amounts of fertile silt in the adjoining wetlands, providing nutrients for an abundant vegetation, among others, lotus, papyrus, Nile lettuce, and water caltrop. Due to decaying plant matter, the layer of organic silt in the marshes is several meters

1

Ilebo is the terminal for shipping on the Kasai River. In colonial days it was called Port-Franqui. Due to a lack of river maintenance, at present, even 40-ton barges cannot travel between Bukama and Kongolo. 3 The main lakes are: Kasibasiba, Kabwe, Kabelwe, Kalongo, Upemba, Kafundo, Kana, Lunda, Kisale, Tala, Zimbambo, Kabamba. 2

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From the Source to Kisangani: The Upper-Congo

Fig. 3.3 The vessel Roi des Belges on the slipway in Kinshasa in 1888, its stern paddle wheel removed. That year the vessel explored the Kasai watershed in a journey that lasted five months while traversing 3000 km [1864 mi]. During a storm on the Fimi River in 1906 the ship would founder with all lives lost. (HP.1958.40.136, collection MRAC Tervuren; photographe non identifié, 1888)

thick. In the wet season the lush, silt-borne vegetation starts to float, often as islands, hectares large, and in the wind, these are pushed off, taking with them unsuspecting wildlife and fishing huts. It is into this lake that the first important tributary of the Lualaba/Congo River empties: the Lufira (Fig. 3.3).4 The Lufira also has its headwaters near the Zambian border, 50 km [31 mi] east of the source of the Congo River. There it is still known as the Kapande. At the city of Mwadingusha (formerly known as Cornet Falls) a hydro-electric dam5 retains a reservoir with the same name that floods back into Lake Tshangalele. A dam has been built some kilometers downstream with another power station, retaining a smaller reservoir. Over a length of 120 km [74.6 mi] the Kunde-Lungu National Park straddles the river (Fig. 3.4).

4

The Lufira basin covers about 56,602 km2 [21,854 sq mi]. Some of its main tributaries are the Dikulwe, the Quilombo and the Lufwa. 5 The 8 m [26 ft] high levee was built in 1925 but raised three times in the next two decades to eventually 13 m [42.6 ft].

3

From the Source to Kisangani: The Upper-Congo

23

Fig. 3.4 Any economic development in the Congo basin depends largely on the use of hydropower. So, the first scientists and engineers criss-crossing the country were always on the lookout for favorable topography to build dams. Early on numerous potential locations were identified and later some of them were developed as such. One proposal, suggested in 1913, but not acted upon, were the Kiubo-Djuo waterfalls on the Lufira. Note the comments made by the mission members on the map (this is a digital re-draw). For comparison the current dirt track to Likasi (bottom right) is also represented

At Ankoro, 480 km [300 mi] north of Bukama, the Congo River receives the Luvua River,6 navigable for 160 km [100 mi], up to Kiambi with at least 80 cm [2.6 ft] depth in the dry season. Higher up rapids and cataracts prevent navigation. In colonial times, near Piana Mwanga, a run-of-river7 power station with three turbines delivering 3730 kW was built. The Luvua receives its water from Lake Mweru, that itself is fed by the Luapula River, forming the northwestern border of Zambia. The Luapula is navigable from

6

The Luvua basin covers 212,700 km2 [82,123 sq mi], almost half of it located in Zambia. Run-of-River: A hydroelectric development where only part of the river discharge is directed through turbines to produce electricity. The remainder flows freely past the powerhouse.

7

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From the Source to Kisangani: The Upper-Congo

110 km [68 mi] south of the lake and across it, to the border town of Pweto—a total of 275 km [170 mi]. At all times minimum draught is 80 cm. In 1913 it was proposed to build a dam on the Luvua River, at the exit from the lake. This was part of a grander proposal to regulate the Congo River flow by damming upstream rivers and using existing or newly created lakes as reservoirs in the wet season, with the water to be released in the dry season. The Luapula is fed by Lake Banguela in Zambia, a large wetland region, and by the Chambeshi River and several other ones along the way. Back in the DRC, south of Kabalo, a 450 m [1476 ft] railway bridge crosses the Lualaba/Congo. It carries the railroad from Kamina in the southwest to Kindu in the north and Kalemie8 in the east. About halfway between Kabalo and Kongolo, on the east bank, the Congo River receives the Lukuga. It comes from Kalemie on Lake Tanganyika, 250 km [155 mi] away and it acts as a seasonal overflow from the lake. From the Congo River, the Lukuga is navigable upstream for 65 km [40 mi]. Lake Tanganyika has its own watershed,9 fed not only by small mountain rivers on its western side, but by rivers on its eastern side, like the Malagarasi and Rugufu and their tributaries in Tanzania and southern Zambia. Once the leisurely running Upper-Congo River has past Kongolo, it hits a rocky outcrop, in which, over the millennia, it has carved a narrow passage, in 1894 named by the American explorer Richard Mohun, “Hell’s Gates” (Portes d’Enfer). Here another rail/road bridge was built to carry the railway. The reinforced concrete bridge of almost 500 m [1640 ft] long has a central span of 70 m [230 ft]. When it was constructed in 1939, this was the largest span in the world made of reinforced concrete.10 From here on the Congo River twists and turns through a gorge, in places less than 110 m [360 ft] wide. It encounters five groups of rapids, until it reaches Kasongo, 120 km [75 mi] further downstream. Here a more stabilized but intermediate reach of 110 km [68 mi] long allows limited navigation by small boats until Kibombo. At this town rapids again prohibit shipping. It was in this reach, 60 km [37 mi] upstream from Kibombo, at Nyangwe, that Livingstone became the first European to see the Upper-Congo River.11 Halfway between Kongolo and Kasongo the Luama12 joins the Congo. Like the Lukuga it comes from the direction of Lake Tanganyika, but has its source in the mountain range that borders the western side of the lake, at an altitude above 2000 m.

8

In colonial times Kalemie was called Albertville, after Albert I, third king of the Belgians. Lake Tanganyika’s sub-basin is 236,300 km2 [91,235 sq mi] over a third of the Upper Congo’s watershed. 10 The bridge was rebuilt in 1968. 11 Dr. David Livingstone on 29 March 1871. Livingstone had set off from Zanzibar in January 1866 for a trek west, in search of the source of the Nile River. 12 The Luama basin covers 23,200 km2 [8957 sq mi]. Two of its tributaries are the Cilungu and the Luiko. 9

3

From the Source to Kisangani: The Upper-Congo

25

Near Kibombo the Congo leaves the savanna region and enters the equatorial forest that it will not leave until Lukolela, south of Mbandaka. North of Kibombo, the river becomes torrent-like again, up to Kindu, the start of the navigable middle reach of the Congo River, which ends 320 km [200 mi] further downstream at Ubundu. The middle reach has the aspect of a regular channel, bordered by steep riverbanks. There are a few rocky passes where buoyage and beacons were needed for safe passage of barges. Nevertheless, in the dry season, only 90 cm [3 ft] of water are available for shipping. Between the mouth of the Luama River and the city of Kindu, 250 km [155 mi], the Congo forms part of a nature reserve, some 30–40 km [19–25 mi] wide and straddling the river. At Kindu, the railway that circumvents the unnavigable section of the river, ends and barges can again take over transport. The city of Kindu straddles the river, which, at its narrowest, is still 600 m [1968 ft] wide.13 Twenty-four kilometers [15 mi] downstream from Kindu, on the right (east) bank, the Elila joins the Congo. The Elila is navigable for 30 km [18.5 mi], up to the village of Mali. At between 100 and 200 km [62 and 124 mi] to the west, the Congo River is paralleled by the Lomami River, also running northward. It will eventually empty into the Congo, downstream from Kisangani. In between a minor Congo tributary now flows, the Kasuku, a narrow, winding forest stream. South of Kindu it forms the Kasuku Lake. Twenty kilometers [12 mi] downstream from the Kasuku, on the opposite side of the Congo, the Ulindi enters and another 20 km lower, the Lowa.14 The Elila, Ulindi, and Lowa and their tributaries, all find their source in the Mitumba Mountains, lining the western side of the Albertine Rift Valley between Lake Kivu and Lake Edward. From the Lowa River mouth, it is another 120 km [75 mi] downstream to Ubundu. Here two tributaries enter, one on each shore: the Ruiki from the west and the Lilu from the east. In the wet season the Ruiki is navigable for 88 km [55 mi]. At Ubundu the river hits a bottleneck. Within a kilometer the river width shrinks from over 2000 m [6560 ft] to just 550 [1800 ft] m. Two kilometers lower the first rapids appear. This is the end of the navigable stretch from Kindu and the start of the railway to Kisangani to circumvent the rapids between both cities, especially the seven cataracts known as the Boyoma Chutes of which the lowest one, close to Kisangani, is often called Wagenia or Tshunga Chute. It is in this 125 km [78 mi] long stretch that the Congo River, for the first time, crosses the Equator. In this unnavigable stretch of river, between Ubundi and Kisangani, another river enters the Congo from the east: the Maiko. Its entrance is spectacular. A rocky spit juts out into the Congo, making the river here barely 350 m [1150 ft] wide. In 1976 a

13

At the Brooklyn Bridge in New York, the East River has the same width. The Ulindi watershed has an area of 28,650 km2 [11,061 sq mi] while the Lowa basin is almost double at 53,730 km2 [20,745 sq mi]. Tributaries of the Lowa include the Lubitz, the Luhoho and the Oso. 14

26

3

From the Source to Kisangani: The Upper-Congo

project to build a hydroelectric dam across the Congo River was proposed, that would have raised the water level by almost 20 m [65 ft] and eventually allowed navigation from Kinshasa up to Kindu, on top of producing 650 MW of power. The project was never implemented. From Kisangani on, the Congo River starts to make a grand, slow, westerly arc to the city of Mbandaka. The curve has a radius of around 500 km [310 mi] over an angle of 110°. While at Kisangani the river is coming from the south, at Mbandaka the river will be running south again, ready to cross the Equator a second time. From Kisangani the river, now known as the Middle-Congo, starts its 1742 km [1082 mi] long, navigable stretch toward Kinshasa. In the dry season, at the city of Kisangani, the river is 650 m [2130 ft] wide,15 but only 460 m [1500 ft] a kilometer further downstream—with shorelines that are at most 2–3 m [6–10 ft] higher than flood stage. At Kisangani two rivers join the Congo: The Tshopo and the Lindi. In fact, the Tshopo joins the Lindi 6 km [3.7 mi] upstream from the junction with the Congo,16 therefore the City of Kisangani is squeezed between three rivers: the Congo to the south, the Lindi to the west, and the Tshopo to the north. On the Tshopo, and at the edge of the city, a hydroelectric dam provides power since the 1950s. Large, flat-bottomed barges17 connect Kisangani with Kinshasa on a regular basis since 1904 (Fig. 3.5). While the Congo River downstream from Kisangani is considered the MiddleCongo, I jump a bit further down to hook up temporarily with the Lomami River. The Lomami is a major flow contributor,18 to the Congo River. At 1280 km [795 mi] long, it is navigable for 390 km [242 mi], up to Litoko. The river’s head is on the Kamina plateau, near the city with the same name. The river has its own watershed, squeezed in between the Lualaba to the east and the Kasai basin to the west. While the Lualaba or Upper-Congo has a 728,900 km2 [281,430 sq mi] basin19 (larger than the state of Texas) the Lomami has only 103,900 km2 [40,116 sq mi] but that is still larger than Iceland. From its source, the Lomami picks up several minor tributaries from the west, but practically none from the east, as the Lualaba/Congo drains most of the land on that side. The longest tributary to the west of the Lomami is the Lukashi, emptying in the Lomami at 5°43′S–25°50′ E. In its lower course the Lomami is dotted with islands and its width in places is five 500–600 m [1640 to 1970 ft]. Back to the Congo River. Between Kisangani and the mouth of the Lomami, the Congo widens, and large islands begin to appear. The first one is Yaoseko (formerly

15

On January 11, 1937, a discharge of 6886 m3/s [243,176 cfs] was recorded. The Lindi basin covers 63,250 km2 [24,421 sq mi]. 17 Due to a lack of river maintenance, at present, only 800-ton barges can ply the Congo between both cities. 18 In 1937 three measurements at Yankwamu—65 km upstream of the Lomami—gave a discharge of 1854 (January 5) & 1126 m3/s (January 20) [65,470 & 39,760 cfs]. 19 This does not include the Tanganyika basin (236,300 km2) that stretches east into Tanzania. 16

3

From the Source to Kisangani: The Upper-Congo

27

Fig. 3.5 The Tshopo Falls, north of Stanleyville (Kisangani) in 1898. (Photographer: Charles Buls. Thys Family Archive)

known as Bertha Island), 14 km [8.7 mi] long and almost 3 km wide. In the wet season the flow is swift, up to 9.0 km/h [2.5 m/s, 8 ft/s]. The north pass used to be littered with reefs that prevented large steamers transiting during the dry season. In colonial times shallow underwater rocky reefs were broken up to provide safe passage. Further down, at Yaowamia, the river narrows momentarily to 650 m [2130 ft] but then, at Yangambi, it is again 3 km [10,000 ft] wide with various islands. Under Belgian rule, Yangambi was home to a renowned agricultural research station.20 It is 19 km [12 mi] downstream from Yangambi that the Lomami River empties into the Congo.

20

INEAC: Institut National d’études agronomiques du Congo-belge.

Chapter 4

From Kisangani to Mbandaka: The High Middle-Congo and Ubangi

Abstract We have a look at the “High” Middle-Congo, from Kisangani to Mbandaka. This also includes the watershed of the Ubangi, a tributary that drains most of the Central African Republic and Congo-Brazzaville. Mayor affluents within the DRC are the Aruwimi, the Itimbiri, and the Mongala. These rivers enter the Congo from the right (north) bank. The largest sub-basin in the north of the country is the Uele. It drains into the Ubangi at the border city of Yakoma. In this middle reach, the Congo River runs through the equatorial forest and is for the majority wide with large islands strewn along it. Before Mbandaka the Lulonga system enters the Congo River but on the left bank. Keywords Middle-Congo River · Aruwimi · Itimbiri · Lulonga · Uele · Ubangi · Stanleyville The first major tributary of the Middle-Congo River, downstream from the Lomami, is the Aruwimi, a good 100 km [62 mi] to the northwest. It is navigable to Yambuya, 160 km [99 mi] upstream. The National Park of the Okapi has been established where the Ituri and the Nepoko join to form the Aruwimi.1 Both rivers, as do numerous smaller ones, find their source on the high grounds, west of Albert Lake, in the northeastern corner of the DRC. At the confluence with the Congo lies the town of Basoko. In the 1950s, barges from 500 to 800 tons would connect the town with Kinshasa (Fig. 4.1). Like the Aruwimi, also on the north bank, the Itimbiri River joins the Congo, 365 km [227 mi] downstream from Kisangani. The Itimbiri, formed by the meeting of the Rubi, de Likati, and the Tele, is navigable from the Congo upstream to Aketi (257 km or 160 mi), where the river is still 170 m [560 ft] wide. On December 18, 1936, a flow of 384 m3/s [13,560 cfs]2 was recorded. Aketi used to be the railway head for the 840 km-long [522 mi] network of narrow-gauge railways (Vicicongo) in the Uele region. In 1910 the river was still considered navigable for small steamers 1

The Aruwimi basin covers 118,970 km2 [72,962 sq. mi] and at Yambuya it was recorded as having a discharge of 1290 m3/s [45,555 cfs] on December 29, 1936. 2 That discharge is comparable to the Potomac River near Washington DC. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_4

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From Kisangani to Mbandaka: The High Middle-Congo and Ubangi

Fig. 4.1 The Middle-Congo from Kisangani to Mbandaka and the Ubangi/Oubangui with selected secondary watersheds

up to Likati and along the Rubi up to Buta. Here the Rubi is only 70 m [230 ft] wide, while at Likati the river, with the same name, is just 50 m [164 ft]. The Congo River, now flowing through the Equatorial Forest, has a wide riverbed. Just downstream, at Bumba, the river is over 20 km [12 mi] wide. This city is still 1337 km [830 mi] upstream from Kinshasa. In colonial days it would take eight and a half days to reach Bumba from Kinshasa by steamer, but only 5 days for the return voyage. Until 1902 this was the last stop for navigation on the Congo River. At Bumba the river is still at an altitude of 375 m. It takes another 300 km [186 mi] to the west before we reach the confluence of the Mongala River with the mighty Congo. This river is navigable for 344 km [213 mi], up to the town of Businga. The Mongala3 is formed by the meeting of the Ebola (“White Water”) and the Dua (“Black Water”) just above Businga. The navigable part is sinuous, but since the river is 250 to 500 m [820–1640 ft] wide, large barges have no trouble navigating safely. Between the Itimbiri and the Mongala, near the town of Dobo, 39 km [24 mi] west of Bumba, the Congo River reaches its most northerly point, being 2°13′ N. Further west, 15 km [9 mi] downstream from Lisala, the river narrows to 4 km [2.5 mi] due to the Upoto-Umangi hills, a range that stretches northward from the river. After that the Congo widens again, enveloping some large islands—one, Esumba Island, 50 km [31 mi] long. In fact, for almost 1300 km [808 mi]—from 3 The Mongala basin covers 58,050 km2 [22,413 sq. mi]. Eighty-two kilometers upstream, at Akula, a discharge of 460 m3/s [16,245 cfs] was recorded on February 11, 1937.

4

From Kisangani to Mbandaka: The High Middle-Congo and Ubangi

31

the mouth of the Lomami to the town of Bolobo, north of Kwamouth, the Congo River runs wide, with countless islands, through the ancient lakebed that once covered central Africa. Swampy floodplains lie on both sides of the river often tens of kilometers wide. Past the mouth of the Mongala we encounter another large island, Nsumba Island. It is over 100 km [62 mi] long and in places 10 km wide. The changing seasonal water level constantly shapes its shoreline. When we hit the town of Makanza,4 we are 85 km [53 mi] downstream from the mouth of the Mongala. Here we are still 919 km [571 mi] from Kinshasa and already 810 km [503 mi] from Kisangani. The river is at an altitude of 370 m [1210 ft] above sea level. It is one of the many ports of call on the river. Several streams wind their way through the tropical swamps, not always with a clear exit into the Congo. The Moeko, unnavigable, coming from the north, near the watershed of the Ubangi and empties in the Congo at 1°48′30″ N–19°28′15″ E. At Makanza the Giri and the Moanda leave the swamp through several channels (Fig. 4.2).

Fig. 4.2 The double-decker Princesse Clémentine arriving at Bolobo in 1898, with Belgian guests on an excursion up the Haut-Congo. A lot of curious indigenous onlookers as those visits would also bring special goods from Kinshasa, not available locally. The stern wheeler Princesse Clémentine was lost at low water on the cliffs at the Swinburne Pass that same year (Mouvement Geographique 1898, coi. 581). (Photographer: Charles Buls. Thys Family Archive)

An early CFS post, Makanza was founded as New-Antwerp (“Nouvelle-Anvers” or “NieuwAntwerpen” in Dutch) in 1884.

4

32

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From Kisangani to Mbandaka: The High Middle-Congo and Ubangi

Where the Congo is already flowing southward, 155 km [96 mi] downstream from Makanza, the Lulonga River5 enters the Congo from the east. This river is navigable up to Basankusu (180 km, 112 mi). Here the Lopori and the Maringa join to form the Lulonga. The Lopori is navigable for another 454 km [282 mi] to Simba and the Maringa up to Befori, 408 km [254 mi]. Both have different tributaries and drain the entire area between the arc of the Congo River in the north, the equator in the south, and the Lomami watershed in the east. The Lulonga shoreline is low, prone to flooding in the wet season. Under these circumstances, the riparian lands are marshy. From the mouth of the Lulonga it is 56 km [35 mi] downstream the Congo to the confluence with the Ikelemba. This river is navigable for 137 km [85 mi] to Bolomba. Four kilometers lower it is the turn of the Ruki. Here lies the city of Mbandaka, still 690 km [429 mi] from Kinshasa. Aside from the many smaller islands, two large ones, each some 20 km [12 mi] long, Nsamballa and Monyondu, split the Congo River into separate channels. Just south of Mbandaka the Congo again crosses the Equator. Eighty-five kilometers [53 mi] below Mbandaka the Congo River receives its second largest tributary after the Kasai River: the Ubangi. We temporarily leave the Congo River to go north again, this time to follow the Ubangi River upstream. For 480 km [300 mi] the Ubangi forms the border between the DRC and Congo-Brazzaville. Further upstream the Ubangi marks the boundary of the DRC with the Central African Republic. In its upper reaches, the Ubangi is formed by the convergence of the Bomu and the Uele near the DRC city of Yakoma, 1060 km [660 mi] upstream from its confluence with the Congo River and at an altitude of 470 m [1542 ft]. Where the Bomu and the Uele meet, the border continues further east along the Bomu River until its source at about 5°01′ N–27°26′ E, the tri-border area at an altitude of 730 m [2395 ft], where the DRC, the Central African Republic, and South Sudan meet.6 The Uele,7 running south of the Bomu and some 1200 km [746 mi] long, starts at Dungu, at the convergence of the Kibali and the Garamba rivers. On its way downstream, the Uele picks up different tributaries. The most important ones on its right bank (north) are, in descending order: the Duru, the Gurba, and the Uere. On its left bank (south) the Bomokandi. The Ubangi, on its way downstream, on the DRC side, receives two tributaries: the Lua, navigable over 131 km [81 mi], up to Mogalu, and the Giri, close to the confluence with the Congo, which is navigable for small, motorized vessels over 177 km [110 mi]. In the early twentieth century, the terminal would have been at a settlement called Bosesera. The Giri meanders, with many sharp and narrow bends,

5

The Lulonga basin covers 84,350 km2 [32,568 sq. mi]. At Losombo, 100 km [62 mi] upstream, a discharge of 1045 m3/s [36,904 cfs] was recorded on February 23, 1937. 6 From that point on, the border between the DRC and South Sudan is formed by the watershed between the Congo and Nile basins. 7 The Uele basin covers 135,070 km2 [52,151 sq. mi] and the Bomu 171,156 km2 [66,083 sq. mi].

4

From Kisangani to Mbandaka: The High Middle-Congo and Ubangi

33

through the inundated equatorial forest, which would make for difficult shipping maneuvers. The Ubangi itself is navigable for 600 km [373 mi], up to Bangui, capital of the Central African Republic across from the town of Zongo, on the DRC side of the river. For the next 80 km [50 mi] upstream, six sets of rapids8 prevent any further shipping. In 1910 it was still considered that navigation was possible further upstream, from a settlement, then called Mokoange, up to Mobayi-Mbongo (then called Banzyville).9 The discharge of the Ubangi River has been falling since the 1970s. The river was navigable during 8 months of the year, today only 4–5 months of the year. Although the river is shared by three countries, there is no common governance: no common navigation code, no coordinated buoyage system, no common dredging policy, wrecks are not removed, and no navigation charts are available. The three countries do not even use the same geodesic reference system. As the Ubangi, some 3 km [10,000 ft] wide and strewn with alluvial islands, comes in under a shallow angle to the also wide Congo, the waters of both rivers mingle and merge over a length of 20 km [12 mi].

8 From downstream to upstream: the Sho, Kuna, Kumba, En-Avant, Elephant, and Mokoange Rapids. Near Mokoange the narrow Bemo River was also navigable. 9 In 1887 an expedition under Belgian lieutenant, Alphonse Van Gèle, had managed to disassemble the En Avant steamer and carry it around the rapids to further explore the Upper-Ubangi River and its tributaries.

Chapter 5

The Low Middle-Congo: From Mbandaka to Tsumbiri

Abstract Two large systems, north of the Kasai River and south of the MiddleCongo, need to be looked at next: The Ruki/Tshuapa system and the Fimi/Lukenie watershed. Both lay hidden in the dense tropical forest. Most of the larger rivers are partly navigable, but the lack of large population centers has reduced traffic. The Lukenie River forms the border between the tropical forest in the north and the wood savanna in the south. As for the Congo River itself, its valley now approaches the Crystal Mountain range. The riverbed is at times very wide, 3 to even 9 km, with a couple of headlands that separate one “pool” from another. Keywords Middle-Congo River · Mbandaka · Coquilhatville · Tsumbiri · Lake Mai-Ndombe From Mbandaka on, we enter the third map of our journey down the Congo River (Fig. 5.1). Immediately after the confluence of the Ubangi with the Congo, at the BrazzaCongolese city of Liranga, the Congo hits a headland and narrows to 2500 m after which the river widens again to 10,000 m [6 mi]. For the next 60 km [37 mi] the river forms the Isungu Pool, littered with tens of elongated islands. The pool ends at the DRC city of Lukolela where the width is barely 1500 m [4920 ft]. The river constriction that forms the pool is at both ends marked by cliffs, 20–25 m [65–82 ft] high. Below Lukolela three other major tributaries join the Congo from the Brazza side: the Sangha, the Likouala-Mossaka, and the Alima. The Sangha comes straight from the north, but drains mostly the land west of it, some even from southeastern Cameroon and the Central African Republic. At this point we need to return briefly upstream the Congo to the city of Mbandaka and the confluence with the Ruki River. The black waters of the Ruki are formed by the confluence of the Busira and Momboyo rivers, a 100 km [62 mi] upstream. The Busira receives the Salonga from the southeast, but its name disappears where the Tshuapa and the Lomela rivers meet. Both these rivers come from the east-southeast and run almost parallel to each other, having their source in the Kasai-Oriental, some 160 km [100 mi] west of the Lomami River, at the parallel of three degrees south. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_5

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The Low Middle-Congo: From Mbandaka to Tsumbiri

Fig. 5.1 The Kasai, Ruki, and Fimi watersheds with selected secondary basins

All these rivers are navigable: the Ruki, after 103 km [64 mi], becomes the Busira from Ingende to Boende on the Tshuapa River (275 km, 170 mi). The Tshuapa is navigable to Bondo (699 km) and the Lomela up to the village with the same name (648 km, 402 mi). At the town of Lomela the river is at best 50 m [164 ft] wide. Today, a bridge carrying the N7 crosses the river. The Momboyo, which becomes the Luilaka in its upper reaches, is navigable up to Ikali (210 + 166 km, 130 and 103 mi). At Mondombe the Tshuapa is still about 200 m [575 ft] wide, and the village lies in the cut bank of a sharp bend, making for a good landing spot.

5

The Low Middle-Congo: From Mbandaka to Tsumbiri

37

The Salonga River, which empties in the Busira River at Ingende, is navigable for 110 km [68 mi], up to Watsikengo.1 The watersheds of these rivers are difficult to determine and in the rainy season marshes develop between those rivers, so that one can navigate by pirogue between watersheds. While the Ubangi comes in on the right bank, on the left Lake Ntomba empties in the Congo through the Irebu Channel. The lake is about 50 km long and 20 km [31 by 12 mi] at its widest, covering an area of 500 km2 [193 sq. mi]. But that can grow by half as much in the wet season. It has a depth of 1.50 m but rises to 4 m [5–13 ft] in the wet season. The lake is navigable all-year-round by tugboats, pushing two, 40-ton barges. In the rainy season, from September to December, units up to 150 tons can even call on Bikoro, on the east side of the lake. Nevertheless, severe weather can at times complicate navigation. Due to minimal elevation changes in the cuvette, watersheds are not always clearly defined. In the wet season one basin might connect with a neighboring one. Ergo, the square kilometers areas can differ substantially (Fig. 5.2).

Fig. 5.2 The large steamer Louis Goffin with two Citas-barges lashed together in a “threesome” near Bolobo in 1923. When 2 years later the privately owned Citas was absorbed into the semiautonomous Unatra, Citas brought 6000 tons of cargo capacity into the new company. (Devroey Family Archive)

1 At 1°01′S–20°44′E. In the early twentieth century shipping along the Salonga River had its terminus upstream of Watsikengo where the Yenge River joins the Salonga. Today it is at the edge of the Salonga North National Park. At the time also the Momboyo/Luilaka and Lokolo rivers were visited by whaler, up to the geographical locations indicated on the map.

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The Low Middle-Congo: From Mbandaka to Tsumbiri

Back on the Congo River, from Lukolela to Bolobo, almost 200 km [124 mi], the Congo River widens again, to between 3000 and 9000 m [3.7–5.6 mi] in the dry season. Bolobo forms a headland again after which, for 45 km [28 mi], the river widens to become the “Pool of Sandy-Beach” until the town of Mpouya, that forms another headland, this time on the Brazzaville side. Along this reach the first signs of the Crystal Mountains appear as submerged rocky outcrops.

Chapter 6

The Last Stretch to Kinshasa: The Congo Couloir

Abstract From Tsumbiri on, as the Congo is now in the foothills of the Crystal Mountains, the channel narrows, deepens, and the flow accelerates. It is called the “Congo Couloir” reach. Early topographical work to establish a base for future navigation charts was especially labor intensive, as a 1912 letter from a Belgian hydrographer testifies. At the end of the Couloir the river forms a pool, the Malebo Pool, at the end of which the Cataract section starts. At this point, the capitals of Brazzaville and Kinshasa face each other across the water. Of the two navigation channels through the Malebo Pool, the one on the DRC side is the deepest, but also the longest. Keywords Congo Couloir · Tsumbiri · Jules Nisot · Maluku · Malebo Pool · Stanley Pool

From Tsumbiri on, the Congo River enters a narrow channel, called Le Couloir or Congo Couloir, a stretch almost devoid of islands. The river now finds its passage through the eastern foothills of the Crystal Mountains. The landscape is changing, the equatorial forest, which we left south of the confluence with the Ubangi River, has now transformed into scrubby savanna and narrow gallery forests in the shadowy bottoms of the valleys of bordering gullies and streams that empty into the mighty river. Due to the river’s large discharge but contracted bed, the depth has increased considerably. Sandbars are gone but submerged rocky outcrops have taken their place. A letter, dated October 8, 1912, by hydrographer Jules Nisot1 to engineer Robert Thys of the Matadi-Leopoldville railway, describes the conditions encountered while surveying the Congo Couloir:

Couloir /ko’ol waar/: A river valley, sometimes a gorge, lined with a mountain range on both sides. 1

Nisot, Jules-Hyppolyte (1875–1923). Mariner & hydrographer. From 1897 to 1906 two tours as a captain in the Bas-Congo. In 1909 Head of the Hydrographic Service in Boma. Did the first regular

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_6

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The Last Stretch to Kinshasa: The Congo Couloir

I thank you warmly for your nice letter and I regret not having had the chance to meet you at the Stanley Pool. I had hoped to finish the chart and buoyage of the various sections of the Couloir by the beginning of October. It was impossible: flood stage arrived rapidly; a lot of topographical reference points have been washed away and in several sections I will have to redo the triangulation. Since last month I completed the chart and buoyage of the section Tsumbiri – Sandy Beach – Bolobo, or 56 river kilometres [35 mi] and our longitudinal sections have a median length of 3 to 4 km! A considerable task, monsieur Thys, considering being shortstaffed and the less-than-appropriate floating equipment at my disposal. In short, an important section is completed and the first large fairway, comprised of red and black buoys, which runs from Tsumbiri to Bolobo. At this moment I am at Mbali,2 where I finished a seven kilometre [4.3 mi] stretch the day before yesterday. Tomorrow, I leave for the Fimi River for another seven kilometres of rocky passage, then two kilometres near Kwamouth after which I return to the [Stanley] Pool with my whole shebang. There I will take on the buoyage, charting and flow measurements from Galina to Kimpoko in the beginning of November. Since there are 49 km [30 mi] to be sounded, I do not think I will finish this section before the end of February, after which I hope I can return home for some rest and assume my old job in Antwerp, unless something unforeseen happens. Respectfully yours,

At the end of the Congo Couloir, at Maluku, 210 km [130 mi] downstream from Tsumbiri, the Congo shorelines suddenly part. Here begins the Malebo Pool, formerly known as the Stanley Pool. The pool is about 30 km long and 25 km [18 by 15.5 mi] wide with a large island, M’Bamou, northwest of the center of the pool and on the Brazzaville side of the border. Dozens of small islands surround M’Bamou. According to chief engineer E. Devroey, in 1941, the main navigation channel in the pool followed the DRC shoreline and was over 5 m [16 ft] deep, except in one, three-and-a-half meter [11.5 ft], shallow spot. The secondary channel follows the Brazzaville side, is shorter, but narrower and less deep. The discharge along the DRC side of the pool is twice that along the Brazzaville side (Fig. 6.1). The pool releases its water on the southwest side into the cataract reach of the Congo River, between the Bacongo suburb of Brazzaville on the north shore and the Ngaliema (formerly Kalima) promontory on the Kinshasa side. The river is about 2 km [6560 ft] wide here, but that figure drops even more when the first rapids appear. We return 136 km [85 mi] upstream from Maluku to the city of Kwamouth, to continue our exploration of the Haut-Congo River system by entering the Kasai River.

surveys of the river. 1912–1913 in the Haut-Congo. Then back on the Maritime Congo until 1920. The Nisot Pass was named after him. 2 Mbali is 23 km south of Tsumbiri and 40 km north of Kwamouth.

6

The Last Stretch to Kinshasa: The Congo Couloir

41

Fig. 6.1 The Malebo Pool and the fairway in 1911. Notice that there are salvage tugs (red) on the ready near the first cataracts (lower left) in case a steamer runs the risk of getting sucked in the rapids (Original tracing paper drawing Thys Family Archive)

Chapter 7

The Upper-Kasai Watershed

Abstract We return upstream toward the Kasai River system that forms the largest sub-basin of the Congo River in the DRC. First, we deal with the Upper-Kasai River, which is the reach above Ilebo, the main shipping transfer point on the Kasai River. We follow the river from its source on the Bié Plateau in Angola—where several of its tributaries also rise—to Ilebo. The Upper-Kasai is navigable, in two separate reaches, together with a short section of the Lulua. That the colonial river charts were not all that accurate, topographically speaking at least, is shown in one example. Keywords Upper-Kasai · Lulua · Luebo · Ilebo · Port Francqui · Tshikapa · Kananga · Luluabourg The Kasai River, called Cassai in Portuguese, is 2000 km [1243 mi] long, and has its source in the Angolan highlands at about 11°30′S–19°12′ E, west of the town of Cassasala,1 at an altitude of 1310 m [4300 ft]. The Kasai basin on its own is one of the largest rivers by volume in Africa.2 Although the main river in the Kasai basin is of course the Kasai River, the basin can be subdivided into two main parts: the Upper-Kasai watershed3 (in yellow in Fig. 5.1), from its source in Angola to the central transfer port city of Ilebo and the Lower-Kasai, from Ilebo to its confluence with the Congo River at Kwamouth. Just downstream from Ilebo, the Kasai receives the Sankuru River, the main tributary coming from the east (dark blue watershed). Several secondary rivers empty directly in the Lower-Kasai, and further westward, the Kwilu River basin (orange) and the Kwango River system (light blue) equally collect numerous tributaries.4 One other

1

One of its early tributaries even dips further south and west, with a source at an altitude of almost 1480 m, at 12°11′S–18°41′E, near the town of Cangonga. 2 It is rated at 890,100 km2 [34,367 sq. mi] an area almost one-third larger than the State of Texas. 3 The Upper-Kasai basin covers 244,820 km2 [94,526 sq. mi], the Lower-Kasai 90,640 km2 [34,996 Sq mi]. 4 The Kwilu basin covers 93,360 km2 [36,046 sq. mi], the Kwango 165,750 km2 [63,996 sq. mi]. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_7

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The Upper-Kasai Watershed

major tributary, joining the Kasai where the river changes its name to Kwa, is the Fimi-Lukenie basin5 (light pink), north of the Kasai. Ninety kilometers [56 mi] southwest of Cassasala—at the bottom, central on the map—is the highest point of the region (1528 m, 5013 ft) where the watersheds draining into the Atlantic and Indian Oceans meet, specifically here the Kasai & Zambezi rivers. Besides the Kasai itself, two others of its main tributaries, the Kwango (Cuango) and the Kwilu (Cuilo), both have their sources nearby,6 as have some of their tributaries. From its source, the Kasai winds its way 400 km [248 mi] east and forms the border between the Angolese provinces of Lunda Sul in the north and Moxico to the south. When the river becomes the border between Angola and the DRC, at an elevation of 970 m [3182 ft], it turns north and runs for another 400 km [248 mi], until the aptly named Angolese border area of Nordeste [“Northeast” in Portuguese], at an elevation of 700 m [2297 ft]. Here a pontoon bridge connects the Angolese and DRC side over the 200 m [656 ft] wide river. Heavily wooded islands dot the riverbed. Then it flows in a northwesterly direction to the Congolese city of Tshikapa. Before reaching this city, the Kasai picks up the Lubembe, immediately after a series of rapids (Chutes Pogge). From here, the Kasai is navigable with barges of between 20 and 50 tons and that for the next 90 river-km7 [56 mi], up to the town of Makumbi. From Tshikapa on, the Kasai describes an elongated, but mirrored S, to the inland port of Ilebo. On the way, the Lulua River joins the Kasai on the right bank. The Lulua, only 300 m [980 ft] wide at this point, joins the Kasai, by then already 1000 m wide, strewn with many islands and plenty of sandbars. The Lulua River is navigable for 58 km [36 mi], up to the city of Luebo where the Wissmann Rapids block further advance. This river has shoals and rocky outcrops that can reduce ship channels to a width of 20 or 30 m [65–98 ft]. Descending the river requires special seamanship to navigate cross currents. Where the Lulua meets the Kasai, with a total width of 380 m [1246 ft], the channel is unstable and draught in the dry season might be reduced to just 80 cm [2.6 ft]. Before the Second World War a Délivrance, pulling two 40-ton barges, would bring supplies to Luebo every fortnight. Ilebo is the economic linchpin in the Kasai system. It is the terminal of the navigable part of the Lower-Kasai. At 820 km [510 mi] upstream from Kinshasa, it has a 500 m [1640 ft] long quay side with several cranes and adjoining a railway 5

The Fimi basin covers 130,540 km2 [50,402 sq. mi] and in 1937, at Kutu, had a recorded discharge of 2417 and 1358 m3/s [85,355 & 47,960 cfs], which puts it close to the Missouri River in the USA. 6 The Kwilu River at 10°57′S–19°18′E (Elev. 1400 m). The Kwango at 11°11′S–19°10′E (Elev. 1350 m). Another tributary of the Upper-Kasai, the Chicapa River, also rises in the same area, at 11° 06′S–19°17′ E (Elev. 1380 m). 7 River-km: A term I started to use when I noticed that there was sometimes a significant difference between the distance along the river, quoted in the literature, and the actual distance that I measured on Google. See more on this in the description of the Kwango watershed.

7

The Upper-Kasai Watershed

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station to transfer goods to the railroad system. This allows freight to be moved to and from Kamina and Lubumbashi in the southeast of the country. At Ilebo the river is at an elevation of 350 m [1150 ft]. The river gauge at Ilebo (between 1945 and 1955) indicated that in January the available depth was 2 m plus, on average, a figure that went up to 3 m in April [6.5–10 ft] while it steadily descended again to barely 20 and 60 cm [0.6–2 ft] in July and August. The river then would rise again to between 1.60 and 2.50 m [5–8 ft] in December8 (Fig. 7.1). The city of Ilebo symbolically divides the Kasai River into two main reaches: the Upper and Lower-Kasai. From the Angolese border to Tshikapa the Upper-Kasai is littered with rapids and waterfalls, but from Tshikapa (Elev. 440 m, 1444 ft) to Makumbi, a reach of 80 km [50 mi], the waterway is navigable by 20-to-50-ton barges. Then, past Makumbi, and up to Ndjoko Punda,9 the river is again strewn with rapids. After that, the entire Kasai River is navigable for the remainder of its course, 789 km [490 mi]. From Ndjoko Punda on, the Kasai can be subdivided into five characteristic landscapes: 1. To Ilebo, 184 river-km [114 mi], a narrow course, 1.10 m [3.6 ft] depth in the dry season, quite winding with a swift flow. 2. From Ilebo to Kilomuana, 329 river-km [204 mi], the river is wide—2000 to 3000 m [6560 to 10,000 ft]—and has good depths, but it also has thousands of islands and even more shoals. 3. Between Kilomuana and Bendela, 78 river-km, the riverbed is again confined with lots of rocky outcrops. At times, the width is reduced to less than 600 m [2000 ft]. 4. From Bendela, where the Kasai is still at an elevation of 300 m [984 ft], to Lediba (134 river-km, 83 mi) the river spreads out again, with a multitude of islands and shallows. Near Mushie the river has a width of 5000 m [3 mi] with a swamp-like island, 22 km long [13.7 mi], crisscrossed by winding, shallow channels. In colonial times it was called the Wissmann Pool. Downstream from the city of Mushie, where the Fimi joins the Kasai, the Kasai changes its name to Kwa. A short section of the Kwa narrows to 500 m [1640 ft], but vegetation patterns on the left (south) bank indicate that during floods the river can widen substantially. Here two more “pools” widen the Kwa to over 3000 m, first the Kraal Pool and then the Lediba Pool. 5. From Lediba to Kwamouth, only 48 km [30 mi], the Kwa narrows again into gorge-like reaches with widths of barely 4 or 500 m [1.300–1650 ft]. In these

In 1942 and 1943, the discharge of the Kasai River at Ilebo fluctuated between 3004 m3/s (April 1943) and 1260 m3/s (August 1942) [106,085 & 44,496 cfs]. 9 In colonial times called “Charlesville” (5°27′30″S–20°59′10″ E). Close to the larger city of Mutombo Lamata. 8

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The Upper-Kasai Watershed

Fig. 7.1 Enhanced navigation charts Nos. 1 and 2 of the Upper-Kasai River, upstream from Ilebo, in colonial times. In red-dotted overlay, the actual riverbed with the main islands. The topographical reality is clearly quite different from the navigation chart at the time. That over decades the river could have moved that far is an argument that holds “no water.” The contour lines (for clarity not represented on this map) confirm that the actual riverbed is sharply restricted by the surrounding hills. (Adapted from: “SVN, Album de la rivière Haut-Kasai.” Echelle 1/25,000. No date. Originals held by MRAC)

places, the river flow can be quite turbulent.10 With its great depths this section used to be called Gorges du Kasai. Where the Kwa enters the Congo River, the water level is at about an elevation of 284 m [932 ft] (Fig. 7.2). 10

In the inter war period the Kasai River at Kwamouth was recorded having an average discharge of 9930 m3/s [350,675 cfs].

7

The Upper-Kasai Watershed

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Fig. 7.2 Three flat-bottomed vessels at the wharf in Leopoldville-Kinshasa in 1898. In the foreground, on the slipway, the 40-ton, double-decker Princesse Clémentine. In the background its sister-ship the Ville de Bruges and in between, barely visible (see the black arrow) the small, 6-ton, single-deck, Baron Lambermont. The Baron Lambermont would founder at the Kingushi Rapids on the Kwango River in 1904. (Photo taken by Charles Buls, at the time mayor of Brussels and visiting the CFS for the inauguration of the railway Matadi-Leopoldville. (Thys Family Archive))

Chapter 8

The Sankuru, Fimi-Lukenie, and Lower-Kasai Tributaries

Abstract Downstream from Ilebo, navigation on the Lower-Kasai is more common. Especially the Sankuru River once even allowed shipping up to PaniaMutombo. We briefly revisit the Lukenie and look at the Mai-Ndombe Lake and its navigable tributaries. Here also we show that on the Lukenie the consecutive 156 navigation charts were not particularly correct in the topographical sense, but still an excellent guide for local skippers. As for the Loange River, south of the Lower-Kasai, two sections, near Kalema and Bushongo, are discussed in more detail. Some of the other Lower-Kasai rivers include the Lubue, Lié, and the Kamtsha. Keywords Sankuru · Lubudi · Lukenie · Lower-Kasai · Bakwanga · Loange · Bushongo · Kalema

8.1

The Sankuru River System

Twenty kilometers [12 mi] downstream from Ilebo, the Sankuru River1 enters the Kasai from the east. The main tributaries of the Sankuru are the Lubudi, the Lubefu, the Lubi, Mbuji-Mayi, Luilu, and the Lubilash.2 In 1886, the first European to navigate the Sankuru River was the German doctor and anthropologist Ludwig Wolf in the steamer En Avant. He travelled upriver to 5° 25′S where rapids, later named after him, blocked further progress. In 1907 the small steamer Bodson managed to pass the first two sets of rapids but was stopped by the third set, 4 km [2.5 mi] upstream from the first. Between the world wars, it was suggested to harness the rapids by building a hydropower dam with lock and hence open the Lubilash and the Mbuji-Mayi rivers (then known as the Bushimai) for

1

The Sankuru basin covers 152,000 km2 [58,688 sq. mi] and in May 1937 a discharge of 3741 m3/s [132,112 cfs] was recorded. 2 Upstream from the Wolf Rapids (Pania-Mutombo), the Sankuru becomes the Lubilash. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_8

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The Sankuru, Fimi-Lukenie, and Lower-Kasai Tributaries

navigation. Close to the city of Mbuji-Mayi3 nevertheless, the Lubilash is blocked by the 19-m-high [62 ft] rapids of Dilongo. The major ports of call on the Sankuru are the cities of Bena Dibele (335 km or 208 mi upstream of the confluence with the Kasai) and Lusambo (470 km, 292 mi). Smaller barges ply the river upstream of the “boxed canyon” where cliffs can reach a 100 m [330 ft]. Between 1914 and 1920, Pania-Mutombo, 86 km [53 mi] above Lusambo, was serviced by the small steamer Luxembourg for 6 or 7 months of the year. The river, between 100 and 250 m [330–820 ft] wide, is extremely winding. Upstream from Lusambo the riverbed is composed of gravel, downstream it is sandy. Here the river is wider, with islands and sandbars. The left bank shoreline is covered with luxurious vegetation but is more open on the right bank having forest interspersed with savanna. Between Bene-Dibele and Lusambo the navigable depth often descends to below 1 m [3.3 m]. Further downstream draught might be only 1.2 m. In the 1930s the Sankuru formed a large pool with numerous low, grassy islets that encircled a large, wooded island before joining up with the Kasai. Today, the situation is quite different: the Sankuru seems to have deserted its southern branch around the large island and instead concentrated on a single channel that winds around it to the north. An Otraco steamer from Kinshasa used to call at Lusambo every 2 weeks. The upstream trip took 16 days, the return voyage 10 (Fig. 8.1). Further downstream from Bena Dibele, near the town of Bolombo and opposite from it, the Lubudi4 enters the Sankuru from the south. While the Sankuru at its

Fig. 8.1 Pulling a two-decker, single-boiler vessel onto the slibway in Kinshasa. The men use an onshore capstan to reel the vessel in with a long chain or cable, meanwhile singing a song (a “sea shanty”) to coordinate their movements. Left of it, standing alone, a winch with a similar purpose, albeit for a smaller vessel

3

Bakwanga in colonial times. Today the second largest city in the DRC, after Kinshasa. Not to be confused with the much shorter Lubudi that enters the Kasai River immediately downstream from Ilebo.

4

8.2

The Fimi-Lukenie Watershed

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narrowest is still 300 m [1000 ft] wide—but most of the time much wider with many islands and shallows—the Lubudi, at 70 m [230 ft] or less, meanders through the dense forest, devoid of islands. In the olden days small steamers could go upriver to a place, then called Kashabala, but today apparently forgotten in history. It was at the confluence of a right bank tributary of the Lubudi, near 4°30′S–22°10′ E. The city of Mbuji-Mayi, on the Mbuji-Mayi River, a tributary of the Sankuru, and upstream from Lusambo, connects to the navigable part of the Sankuru via the Lubi River, at a place called Ndomba, 50 km [31 mi] NW of Mbuji-Mayi. Upstream from Bena Dibele, the Lubefu enters the Sankuru. The vegetation pattern suggests that over time the configuration of the convergence changed often and quite remarkably. In 1886, Dr. Wolf, the first white person to see the confluence, reported: The mouth [of the Lubefu] has the form of a delta of which both arms are respectively 30 and 50 m [164 ft] wide. ... Navigation is easy, few islands and sandbanks.

Today, where both rivers meet, the Lubefu is 120 m [400 ft] wide, but that quickly narrows to 90 m [300 ft] and less once you move upstream. Further up it is sometimes only 25 m [82 ft] wide, with many sharp bends. Only small, motorized craft would be able to navigate here. Habitation along the banks is sporadic. In the 1930s small motor craft would go up to the settlement of Samangwa (206 km or 128 mi from the confluence with the Sankuru) and even the town of Lubefu (at 265 km, 165 mi).

8.2

The Fimi-Lukenie Watershed

The Lukenie River runs east-west through the DRC, along the edge of the tropical forest in the north and the shrub savanna in the south. At Kutu, where the 150 km [93 mi] long Lake Mai-Ndombe5 empties into the Lukenie, this last one becomes the Fimi River. While the south bank is swampy, the north bank is higher and loamy. Henri Morton Stanley in 1882 wrote: “... the largest depth encountered in the lake is 7.20 m. The average depth is 4.80 m in this season and 2.50 m [16 & 8 ft] in the dry season.” According to him, the lake covered 1300 km2 [501 sq. mi] while today it is estimated at 2300 km6 [888 sq. mi]. The lake acts as a regulating water body for the Fimi. The north of the lake borders the tropical forest, the southern shores touch the woody savanna of the cuvette centrale.

In colonial days, the lake was called “Lake Leopold II” after the second king of the Belgians and founder of the CFS. 6 Another figure given is 3200 km2 [1235 sq. mi] with 8200 km2 [3166 sq. mi] in the wet season. The average depth would then grow from 5 to 10 m [16 to 32 ft]. See: https://dbpedia.org/page/ Lake_Mai-Ndombe 5

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The Sankuru, Fimi-Lukenie, and Lower-Kasai Tributaries

The lake receives two main rivers: the Lotoi in the northeast, and further south, the Lokoro. The Lotoi River has a unique morphology: between the lake and upstream from Kiri the winding river has numerous lakes, which branch out from the river like a bunch of grapes hanging from a stalk. Still today the town of Kiri is a port of call for barges. Before the Second World War, packet boats, type Délivrance, used to venture further upstream. The Lokoro, much longer than the Lotoi, has a similar “grape” appearance in its lower reach as the Lotoi, but not as striking. Small motor craft with a draught of less than 90 cm [3 ft], can reach Lokolama in the wet season. At that time of year, the entire Lukenie is navigable albeit from Kole to Lodja only by small craft as the river is often narrower than 50 m [165 ft] with sometimes consecutive, multiple sharp bends. In its upper reaches snags form a hazard. On the last 300 km [186 mi] of its course, the Lukenie has many shifting sandbanks with often only a meter of depth or less, complicating safe passage. Above Dekese more submerged rocky outcrops are encountered and rapids here and there speed up the flow to 12 or 15 km/h [10 ft/s or 14 ft/s], dangerous when descending the river. In Dekese the difference between high (November to January) and low water (June to August) is on average two-and-a-half meters [8 ft]. Since improvements to the Lukenie from Dekese upstream to Kole, 222 km [138 mi], would be expensive versus the economic benefit,7 the colonial administration decided against any commercial shipping above Kole. Nevertheless, development of 792 km [492 mi] of navigable Lukenie is already an impressive feat. In August 1935 midshipman Blondé made a reconnaissance of the river after which a navigation chart in 156 sheets was published. The sheets were never updated. Additionally, between 1938 and 1953, a gauge at Kole was regularly read. Readings reveal a water depth of over 3 m [10 ft] in November and December 1938, peaks of 4 m [13 ft] from January to May 1945 and a low of 40 cm [1.3 ft] in June 1943. From 1950 to 1953 the navigable depth ranged between 1.2 m and 4 m [4 and 13 ft] (Fig. 8.2).

8.3

The Lower-Kasai Tributaries

Concurrent to and between 50 and 100 km [31–62 mi] south of the Lukenie River flows the Lower-Kasai River. The distance between Ilebo in the east and Kwamouth in the west is 605 km [376 mi]. Ilebo is the major shipping terminal for convoys by 800-ton barges coming from Kinshasa. From here a railway connects the Ilebo port with Kamina and Lubumbashi in the southeast of the country. Barge convoys can be broken up into smaller units (350 tons) to either continue upstream the Sankuru to Bena Dibele, Lusambo, or Pania Mutombo.

7 Between Kole and Lodja, another 110 km [68 mi], only 15 m [49 ft] long tugs with a 56-kW motor, pushing four barges of 20 tons, would be admissible, and that only during part of the year.

8.3

The Lower-Kasai Tributaries

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Fig. 8.2 A compilation of the last two sheets (155 and 156) of the Lukenie River, downstream from Kole, in colonial times. Dark blue, dash-dotted line, and North Arrow depict the course of the actual Kole River. Arbitrarily we choose bend “A” as a fixed feature and oriented both sheets towards point “B” on the left. As a result, we noticed that the northing on Chart 155 is out by 10.5° and the one on Chart 156 by 6°. The abnormality that stands out is the bend “A.” It is too sharp by almost 20° vs. the actual situation. When we consider nevertheless the rudimentary circumstances under which Blondé did the hydrographic survey a century ago, the result is still quite astounding. This random example indicates that inland navigation was not accomplished according to compass headings and topographical accuracy, but by simply observing natural features like shoreline bends, river widths, island configurations and, importantly, navigational hazards. The river, barely 50 m [165 ft] wide, here is strewn with boulders and sandbars. Only whale boats could run this stretch of the river. Aside from the (approximate) north orientation, the charts have no coordinate references, only river distances in km. (After: “SVN, Album de la rivière Lukenie de Kutu à Kole”. Echelle 1/10,000. 1935. Originals held at MRAC)

Between the confluence of the Sankuru with the Lower-Kasai and the city of Kilomuana in the west, several large streams enter the Kasai from the south. Since the Kasai and the Lukenie to the north now run close to each other, no major rivers enter from that side. The first river we encounter is the Loange, at 80 river-km [50 mi] downstream from Ilebo. In the mid-twentieth century, this tributary used to be navigated up to the town of Kalema, immediately downstream from the convergence with the Tobi River, some 190 river-km [118 mi] upstream from the Kasai. Today at Kalema (5° 50′S) the N1 motorway, connecting Kikwit with Tshikapa, crosses the river. At that point, the river is still between 300 and 400 m [1000 and 1300 ft] wide, dotted with a lot of sandbars and islands. In 1898 the river was described as follows: The Loange is a beautiful river with deep grounds. The waters are reddish, and the average width is between 200 and 250 m, with pools going to a width of 500 and 600 m. The alternating riffles and pools produce wild waters, shaking our little steamer Katanga like a walnut shell. For small steamers, at high water, these violent, whirling eddies are frightful. At night, when all else is calm, one can imagine being at the seaside.

In 1937 the river was cleared of snags up to Lake Matshi, 150 river-km [90 mi] upstream, by the Compagnie du Kasai that operated small but powerful steamers, towing two 20-ton barges alongside. The amplitude of the water levels between wet

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The Sankuru, Fimi-Lukenie, and Lower-Kasai Tributaries

and dry season was measured as 75 cm [2.5 ft] at Kalema, but still one-and-a-half meters [5 ft] further downstream at Bushongo (Fig. 8.3). The existence of this modern overland connection might be the reason that no river transport seems to exist anymore on the Loange. Just south of Kalema the Tobi River enters the Loange and still further south the Luele River, sometimes also called the Lu(t)shiko. This last waterway crosses the border into Angola and reaches as far south as the source of the Loange itself (Fig. 8.4). The next important river entering the Lower-Kasai is the Lubue. In the 1930s it was navigable by 5-ton whalers up to the village of Mwilambongo where today a bridge crosses the river. At best the river here is 40 m [130 ft] wide. On its way to the Kasai, it has plenty of sharp bends. Lieutenant Baron von Nimpsch in 1886 described the Lubue as follows: The Lubue is 60 m [196 ft] wide, has a depth of 4.5 m [15 ft] and the flow attains 1.15 m/s [3.8 ft/s].

This was obviously a snapshot, and it is unknown where and when the lieutenant took these measurements. Later it was established that in the dry season (May to September) the channel depth is 80 cm [2.6 ft], while between October and April that figure rises to over 2 m [6.5 ft]. Nevertheless, the channel is confined and sinuous, although never narrower than 3 m [10 ft]. A multitude of snags makes travel difficult, and paddlers often had to cut their way through by means of a hatchet. At 4°30′ latitude south a rocky outcrop existed, though it did not hinder navigation. Further west the Lié River8 enters the Kasai from the south, but it is only the junction with the Kamtsha River, upstream from the city of Eolo, that once saw regular shipping traffic. The mouth of the Kamtsha is still 98 river-km [61 mi] from the city of Kilomuana. In 1939, 5-ton whalers would travel upriver, as far as past the confluence with the Labui to a settlement called Wawa (at 4°48′S). In the vicinity (Ngoso) a bridge today crosses the river. At this point the river is at best only 30 m [100 ft] wide and the navigable channel spans just 3–4 m [10–13 ft]. In the wet season the thalweg might be 2.5 m [8 ft] deep, while in the dry season it is still 1 m. In 1896, one of the two Europeans to first travel up the Kamtsha, M. Stache, provided us with an excellent description of the river9: The Kamtsha joins the [Lower-] Kasai at Eolo. Its waters are black, deep, and pure. Its width ranges between 80 and 100 m [260 to 330 ft]. From Eolo to Imbolo, the banks are bordered by low plains and navigation is easy. Further upstream the banks become wooded, and the number of snags grow, and this up to Badinga ... from that point on, the width narrows to about 35 to 40 m. The depth remains good, but the winding becomes more pronounced, and the number of snags makes the river more dangerous.

8

In older literature, the Lié is sometimes called the Pio-Pio or Luele. This last name may create confusion with the Luele or Lu(t)shiko, tributary of the Loange we have described earlier. 9 Cited by E. Devroey, 1939, p. 238.

8.3 The Lower-Kasai Tributaries

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Fig. 8.3 The Loange River, south of Bushongo. This is a color compilation of two 1956–1957, black and white navigation charts, numbers 22 and 23 (99 km upstream from the confluence with the Lower-Kasai). The depth of the winding fairway is indicated as being almost 1.5 m. The original maps do not have contour lines, nor elevations, they were simple whiteprints, without detailed on-land features. They were meant to be updated as needed. The complete set—up to 6° S°—was covered by 40 sheets. Only small steamers and later motorboats could travel the Loange River. (Courtesy Flanders Hydraulics, Antwerp for the use of the original charts)

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8 The Sankuru, Fimi-Lukenie, and Lower-Kasai Tributaries

Fig. 8.4 The Loange River near present-day Kalema, at km 155. This is a color compilation of three 1956–1957, black and white navigation charts, nos. 34, 35, and 36. At the time, the city of Kalema did not exist, only three settlements: Mutangiri, Mutumbi, and an unnamed one. The area was a junction of various trails where a ferry would take people and goods across. Today the N1 motorway (in red) from Kinshasa to Lubumbashi crosses the river on a bridge. According to the charts the navigable depth was a minimum of 1 m [3.3 ft]. Notice the indication of snags (#) in the lower left-hand corner. Beaconing details—not on this chart—were added after a test-run in August 1957 with a tugboat pulling three barges. The combination had a draught of 55 cm [1.8 ft], the average flow at the time was measured at 4 km/h [3.6 ft/s]. (Courtesy of Flanders Hydraulics, Antwerp for the use of the original charts)

Chapter 9

The Kwango and Kwilu Watersheds

Abstract The last watershed in the Kasai system we look at is the Kwango, including the Kwilu and its tributaries. The Kwango once had navigation up to the most southerly range in the DRC. At Kingushi though rapids complicated progress. They could be overcome in the wet season and a few modifications were proposed, but not enacted upon as shipping demand never economically developed. Instead, the parallel running Wamba was better suited for barge traffic. As for the Kwilu, shipping went up to Kikwit and the Inzia saw limited traffic also. Keywords Kwango · Kingushi · Wamba · Kwamouth · Kwilu · Inzia · Ossossoff

9.1

The Kwango River System

One large basin on the left (south) bank of the Kasai remains: the Kwango River system. The Kwango mouth is still 56 river-km [35 mi] above the city of Mushie, where the Fimi/Lukenie River enters the Kasai from the north. While the Kwango enters the Kasai near the city of Bandundu, 20 km [12.5 mi] upstream on the Kwango, the Kwilu River joins the Kwango from the east. We will look at the Kwilu separately. At Bandundu, the Kwango is over 500 m [1640 ft] wide. At one time the Kwango used to be the only river in the Kasai basin that was navigable to the most southerly latitude (7°40′ S), the Kasongo-Lunda Rapids1 near the town of Kapita-Suka. Navigation between Bandundu and Kingushi, 295 river-km2 [183 mi], was not problematic for the first half of the journey. Then, from the Benzale settlement on, the river narrows and begins a more winding course with here and there a sharp bend. 1

Formerly known as the François-Joseph Rapids. E. Devroey, in his detailed treatise on the Kasai Basin, p. 231, indicates the distance as 215 km [134 mi]. My cartographic measurements (on a scale of 1:120,000), double-checked, showed 295 km [183 mi]. In other cases where I checked distances, they did not compare either. To distinguish between “Devroey-km” and my measurements, I started using the term “river-km.” As Devroey compiled his study from a multitude of reports by different subordinates, over 80 years ago, certain discrepancies in the figures today are inevitable.

2

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From about 200 river-km [124 mi] south of Bandundu the river widens again with several pools and dotted with islands and shoals. Today, at Cité Pont-Kwango, 240 river-km [149 mi] upstream, a bridge carries the N1 motorway across the river. In the early twentieth century, the river was irregularly traveled by packet boats, up to Kingushi where rapids originally blocked shipping. Immediately past the rapids, the river was navigable again3 for another 300 km [186 mi]. Until the arrival of the Matadi-Kinshasa railway in 1898, the CFS administration had great difficulties in transporting goods between those two places as all freight had to be portaged from the west through the hills and valleys of the Crystal Mountains. As an alternative, an easier caravan route was opened that followed the west-to-east border with Angola and ended at Popokabaka4 on the Kwango. From there boats could continue the journey downstream the Kwango, the LowerKasai, and then the Congo River to Kinshasa. A long way round! To overcome the rapids at Kingushi the government had a 200-m-long and 30-m-wide [650 and 100 ft] channel blasted out of the rocks on the right bank of the rapids to connect the two reaches. Over 2 dry seasons 500 Bayaka people “assisted by a few men from the coast to look after the gate structures and the equipment” toiled to get the task accomplished. The idea was to reduce the drop of the river to 50 cm over 1 km [1.6 ft over 3300 ft]. Two years later it was reported that, at the entrance to the “canal” the drop was 80 cm over 60 m [2.6 over 200 ft], an obstacle considered manageable for a packet boat. Nevertheless, in 1904 and 1907 two steamers foundered in the area. In May 1914, Engineer-captain Robert Thys5 proposed to build a small navigation lock at the foot of the rapids on the eastern side of Mokengi Island and an approach wall upstream from the island to regulate the river flow and prevent whaleboats from being sucked into the rapids on the western side. By that time though, the colonial government was shifting its priorities from river improvements to railway construction as the investment in rail was cheaper and provided easier, faster, and more reliable transport. However today, in the dry season, one can still distinguish the remnants of this bit of early Congolese River Engineering (Fig. 9.1). At the time goods going upriver by whaleboats in the dry season were unloaded at a jetty just shy of the Bwesi Rapids (see the map). From there they were transported by pirogue to almost upstream from the mouth of the Fufu Rivulet. From that point

The first steamer on the Upper-Kwango (Kingushi-Kapita-Suka), the Colonel Wahis, had been brought overland in 276 separate loads along a newly established caravan route from Kimpese in the west, to Popokabaka. 4 Popokabaka lies 350 km [217 mi] upstream from the Kasai River and still 258 km [160 mi] from Kapita-Suka in the south. 5 Robert Thys was the son of Albert Thys, the officer turned businessman, who headed the construction of the vital Matadi-Leopoldville railway between 1890 and 1898. In the beginning of the First World War Robert was instrumental in flooding the lowlands along the Belgian coast, thus stopping the German advance. For the remainder of the war, he headed the engineer company responsible for maintaining the flooded frontline. 3

9.1

The Kwango River System

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Fig. 9.1 The Kingushi Rapids and the navigation “canal” circumventing the main rapids. The Kingushi downstream gauge would indicate that between November and January the water depth at the foot of the rapids would be around 2.5 m and rise to over 4 m [8–13 ft] in April. Between July and September, the water level could drop as much as 3.5 m [11.5 ft], leaving only half a meter [1.6 ft] in the dry season. In 1932 nevertheless soundings of close to 2 m [6.5 ft] were registered in the bypass (see inset)

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loads were carried along a 2-km-long [6560 ft] dirt track, past the Government Post from where another packet steamer would bring them to Tembo in the south. In the same way goods coming from upstream were moved down the rapids. In principle, this river schedule was to be maintained monthly but proved to be unreliable. A waiting time of 6 weeks was common. Until 1918 and during the wet season, a steamer would be hauled past the rapids by means of a cable secured on land. Then it would stay on the Upper-Kwango for the duration of the dry season. In 1918 the small navigation bypass, which was cleared 2 years earlier, was described as having “a width of 19.5 m upstream, 8 m halfway and 58 m at the downstream end [64, 26 & 190 ft].” While Chief-Engineer Vandercam in 1913–1914 had authored a detailed report on the Kingushi Rapids, in the August 1932 dry season hydrographer Shigaeff revisited the site and measured the hydraulic grade over the channel as being 85 cm over 120 m [3 ft over 393 ft] with a quite variable flow “in certain spots measuring over 2 m/s”. Of course, this was just a snapshot. Thus, Unatra never managed to establish a regular service up to Popokabaka. Only in 1933 and 1936 a Délivrance packet of the Waterways Dept. travelled up to Kingushi. Buoyage and beacons to mark the passes would have been required to make regular packet service feasible, but with the projected high maintenance cost and without any major commercial value, the plan was scrapped. However, still in 1939 there was the idea to overcome these rapids to create one continuous navigable stretch along the entire Kwango River. Then chief engineer of the colonies, Égide Devroey, proposed to build a longitudinal levee out, downstream from the Mokengi Island, as such creating a natural lock, 20 m wide and 1.5 m deep [65 and 5 ft] at low water. This would raise the water level in the channel downstream while at the same time lowering the flow velocity. This procedure had been used successfully on the Rhine River at Bingen (Bingerloch). Eventually no improvement measures were taken as alternative and more economical ways to open the region were established (a road west toward the Matadi-Kinshasa railway and a road northeast toward the navigable section of the Wamba River). Part of the Kwango River (Cuango in Portuguese) forms a long and winding border with Angola. It starts 30 km [18.5 mi] upstream from Popokabaka, where the Cuilo enters the Kwango from the Angolese side and ends 270 km [168 mi]—as the crow flies—to the south southeast6 where the border starts to follow a small tributary to the east. Parallel and east of the Kwango, at about 50–60 km [31–37 mi], runs the Wamba, one of Kwango’s tributaries. In between the World Wars, Otraco used to run a freight service with a small tugboat, pulling two 20-ton barges on the Wamba to Mukila (5° S), where further progress is blocked by rapids (Chutes Destain). From Bandundu it took 7 days to reach Mukila, the return trip took only 3 days (Fig. 9.2).

6

From 5°48′S–16°36′E to 8°06′S–17°31′E.

9.1

The Kwango River System

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Fig. 9.2 A colorized adaptation of the 1960s Navigation Charts 11 and 12 of the Congo River, at the confluence with the Kwa/Kasai River. The original whiteprint at Flanders Hydraulics in Antwerp still contains more technical information

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Since it was quickly recognized, in the early twentieth century, that the young Belgian colony would be extremely dependent on river transport for its development, a lot of effort was put into the establishment of navigational aids on the main rivers. In 1917 the Special Hydrographic Service of the colony published an album of the Congo River, based on a preliminary survey. A new edition appeared in 1931, after an update of the cartographic data by Chief-Hydrographer Ossossoff.7 In the 1960s a new album was published. It contained 64 charts, covering the Congo between Kinshasa and Kisangani and each chart was at a scale of 1:25,000. Between Kinshasa and Kisangani 13 local offices of the Hydrographic Service, kept track of any changes made to the navigation route in their area. They would inform the barge masters and would also adjust the signage accordingly. Where the river formed the border between the two Congo’s (DRC and CongoBrazza), navigational beacons were primarily installed on the left—now the DRC— bank of the river. From Makanza on the beacons were installed on both sides, whichever location was more logical. They were intended for vessels going upstream, taking advantage of less violent river currents. Depth in the assigned fairway axis was guaranteed a minimum of 2 m [6.5 ft] at all river stages. Vessels descending the river on the contrary were told to stay a third of the river width from the right bank—the Congo-Brazza side—to take advantage of the swifter currents that were encountered in that part of the river. The sign “Follow the shoreline” included the warning to stay a minimum of 50 m [65 ft] from the shore to avoid rocks (Fig. 9.3).

9.2

The Kwilu River8

The Kwilu River forms the easterly sub-basin that connects to the Kwango River system. The river is navigable up to the major center of Kikwit. Today a bridge on the N1 motorway spans the 130 m [426 ft] wide river in this location. Further downstream, opposite the city of Bagata, the Inzia River empties into the Kwilu. It has three important, right-bank, affluents: the Gobari,9 the Lukula, and the Luie. The Lukula used to be navigated up to Kingungi, but only by whalers, as the river is barely 25 m [82 ft] wide at this point. The Inzia itself was visited by similar small craft, up to Kimbao where the river is just 60 m [197 ft] wide. In the 1930s the Inzia River, typically a meandering waterway with narrow channels and having a flow of between 0.5 and 2 m/s [6.5 ft/s], was traveled by 7

Ossossoff [Ososov], Dmitri Ivanovich (1896–1983): Russian mariner. Left Bolshevik Russia in 1920 for the Belgian Congo. 1922: Did a hydrographic survey of the Rubi and Itimbiri rivers. By 1929 Chief Hydrographer for the Haut-Congo. 1930: Atlas of the Lulonga, Lopori and Maringa rivers. 1938: Lukuga River. Left public service in 1951. Permanently departed the Congo for Los Angeles, CA in 1960. 8 Not to be confused with the smaller Kwilu River in the cataracts region. 9 In 1907 indicated as the Kaffi.

9.2

The Kwilu River

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Fig. 9.3 While navigation signals have a more serious purpose, they can sometimes be the frame for a more romantic setting, like here at Bolobo in October 1936. When the white, reflective triangle in the back (pointing down) is aligned with the one in the front (pointing up) the vessel is following the fairway. The four (colored) rectangles on the front triangle indicate that four buoys follow this beacon. The colors are similar and in the same order as the upcoming buoys. Over 30 different signs could be encountered, often in combination, with a specific aim. Notice the child on the left playing with a bike rim. (Devroey Family Archive)

Otraco’s Délivrance packet boat with two 40-ton barges in tow, 68 km [42 mi] upstream to Mushuni. Here the river was still about 100 m [328 ft] wide. Private companies went even further upstream to load tropical products for export. At Mushuni the Lukula enters the Inzia. Motorized whalers would travel 140 km [87 mi] upstream the Lukula to Kingungi. The first half of this section could be accessed by small 18.6 kW company diesel tugs with a 12-ton capacity, pulling a 10or 20-ton barge. As with all Congolese rivers, snags were a constant worry and clearing them proved to be expensive and time-consuming. On many smaller tributaries it was not economical to do so and regular shipping was simply abandoned or not even attempted. Although the Kwilu does not enter the Lower-Kasai directly—it instead enters the Kwango River 16 km [10 mi] upstream the Kwango—it is an imposing river, has its own 93,360 km2 [36,046 sq. mi] watershed and is navigable for 342 km [212 mi]. In its lower course the river is 600–1000 m [1970–3280 ft] wide, but at the city of Kikwit (320 km or 200 mi upstream from Bandundu) it is only 200 m [656 ft]. Twenty-four kilometers [15 mi] below Kikwit, at the town of Lusanga, the Kwenge joins the Kwilu. The Kwenge used to be accessible upstream up to the settlement of

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Bumba (5°08′ S) by packet boats. There the river is still 50 m [164 ft] wide. The Kwilu itself would receive 350-ton convoys up to Kikwit. As for morphology, the Kwilu can be divided into three sections: traveling downstream from Kikwit to Bulungu (87 km, 54 mi) the river has typically small pools, not a lot of sand but a rocky riverbed. From Bulungu to Bagata (143 km, 89 mi) the riverbed is sandy with the odd rock along the riverbank. Finally, between Bagata and the Kwango River (100 km, 62 mi), a deceiving thin sand layer overlays the bedrock that emerges in places reaching far into the river, making navigation dangerous. In the intervening pools the water flow can be slow but in the narrow sections the velocity reaches 1.5 m/s [5 ft/s]. At Kikwit the water level can vary by two-and-a-half-meters [8 ft] between dry and wet season. Besides journeys by private companies in the region, in 1939 four to five trips a month were made by Otraco steamers from Kinshasa, 690 km [430 mi] downstream, to Kikwit. The voyage would take 10 days, the return trip only five. In 1930 an 80-km-long [50 mi] section of Kwilu River, upstream from Kikwit, past the rapids,10 was cleared of obstacles to make the Upper-Kwilu navigable for motorized whalers. On the Luie, tributary of the Inzia, motorized whalers could go 50 km [31 mi] upstream to Kiwala (4°44′ S). Today a bridge on the N1 motorway crosses the river in this spot. At best the Luie is only 25 m [80 ft] wide here (Fig. 9.4).

Fig. 9.4 Délivrance V again, moored somewhere on the Congo River system in 1913. Next to the wheelhouse eight rifles are visible, all with fixed bayonets. (HP.1958.40.129, collection MRAC Tervuren; photo L. Broun, 1913 Tous droits réservés) 10 In 1893 the rapids were named by Major W. Parminter after the steamer he was on when he reached the rapids: L’Archiduchesse Stéphanie.

Chapter 10

The Congo Cataracts

Abstract Although not navigable, we also look at the Congo Cataracts. Many smaller tributaries empty in the Congo from both sides, surrounding Crystal Mountains. In the twentieth century a few hydroelectric power stations were built on these tributaries, but the potential is still enormous. Over 350 km the Congo River drops 265 m (Exact figures are hard to come by). The largest hydro stations to date are at Inga and more could be built. Civil engineers even envisioned a canal that would overcome the cataracts and connect shipping between the Lower and Upper-Congo, but the expenditure would be astronomical. Keywords Congo Cataracts · Crystal Mountains · Inga · Manianga · Luozi · Isangila At the Malebo Pool, the Haut-Congo ends, and a new section begins: the region of the Cataracts.1 It is all but the last stretch of the Congo River toward the Atlantic Ocean. Between Kinshasa and Matadi, where over the millennia the river has carved its way through the Crystal Mountains, it descends 260 m over 350 km [853 ft. over 217 mi]. From Matadi on, the Congo River is navigable for ocean-going vessels: it is the Maritime Congo (Fig. 10.1). The hills in the Crystal Mountain range are covered in savanna, intersected by narrow strips of forest in the abundant valleys. Today, the savanna landscape is primarily the result of human activity: deforestation, shorter crop rotation cycles, brush fires, unchecked clearing to fulfill the demand of the growing urban settlements in the region, and tree cutting for the supply of charcoal (Fig. 10.2). The cataracts reach can technically be divided into three sections: the upper one, between Kinshasa and Manianga with 60 steps in 6 groups, followed by a more-orless navigable part between Manianga and Isangila, 139 km with a fall of 22 m [86 mi and 72 ft] over five rapids.

1

Cataract: From Greek katarrassein, to dash down. Originally only used for the rapids on the Nile River, then in a broader sense, for rapids on the African continent. Today often used as a synonym for rapids in general. In rapids water moves fast over a rocky, uneven slope. A waterfall denotes a body of water dropping over a cliff of a certain height.

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Fig. 10.1 The cataract region, from Kinshasa top right on the map to Matadi bottom left, the main seaport for the country. Already in 1898, a narrow-gauge railway was built to circumvent this unnavigable stretch of the Congo River. The Kwilu River on this map is not to be confused with the much larger and longer Kwilu River of the Haut-Congo, discussed above

Fig. 10.2 The cataract reach with the main rapids and waterfalls. The current Inga I and II hydroelectric stations north of Matadi are located near the Shongo Rapids with an intake at the Sikila Rapids. The “Grand Inga” Power Project would take water from the Kianda Rapids to below Kanza

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According to engineer E. Devroey in 1941, this section itself can be divided into (1) Manyanga to Lamba (27 km, 16.7 mi), (2) The “Calm Region” of Luozi (22 km, 13.7 mi), (3) The reach from the Tshumbu to the Itunsima Falls (15 km, 9.3 mi), (4) The Itunsima to Zambi Rapids (14 km, 8.7 mi), (5) The Zambi to Kanzi Rapids (19 km, 11.8 mi) and finally, (6) The so-called “Long Reach” from the Lufudi River to Isangila (32 km, 30 mi). The lower and third section of the cataracts, between Isangila and Matadi, has another 60 steps of rapids and falls. The definition of what constitutes a cataract, a rapid and/or a (water)fall is ambiguous. As for a waterfall, one can argue that the water stream “falls” over a precipice and thus the flow spends a certain (albeit short) time completely in the air. Rapids on the other hand are created when the flow passes over an uneven, rocky, and shallow riverbed under a steeper angle than upstream or downstream of the rapid (s). Rapids usually come in a series, hence the plural form of the word. It was the Greek historian Herodotus who in 457 BCE traveled up the Nile and reached the first “cataract” of the Nile, a series of rapids near Aswan. Later Eratosthenes of Cyrene travelled further up the Nile and encountered the following five cataracts. The Greek word “cataract” for rapids or waterfalls thus seems to have caught on with explorers of the African continent who began using the Greek word while exploring other African rivers. Today the word “cataracts” is related to large rivers with a high flow rate, indeed like the Congo or the Nile rivers. If the phenomenon occurs in smaller rivers, one more customary talk of “cascade(s)” (Fig. 10.3). Besides the many and powerful rapids of the cataracts region, there are other spectacular landmarks in the area, like the “Corniche de Stanley,” just north of the mouth of the Lulu River, where Stanley, in 1881 had ordered the Belgian Lt Valcke to construct a cliff-road towering over the Congo River. Henry Morton Stanley believed a railroad should be build from Vivi to Isangila— on the north bank of the Congo, then goods should be transferred to a packet boat to travel to Manianga, where another railroad could take the freight, along the south side of the river, to Kinshasa. Eight years later Albert Thys, who traveled the Corniche, disagreed, and decided that the best course of action would be to construct a railway directly from the new-to-be-build port of Matadi to Léopoldville/Kinshasa. Away from the Congo Cataracts, on the various tributaries that wind their way through the mountainous terrain, a multitude of smaller but no less impressive rapids can be visited. Some of them have been harnessed for hydroelectric power production. But the potential is still enormous. The most important electrical facilities have been built at Inga, on the Congo River itself, to take advantage of the long and important drop of the water through the Shongo Rapids with enormous flow. A power canal takes water from above the rapids to two stations2 below it. Plans for

2

Inga 1 has a drop of almost 55 m, Inga 2, 60 m. The “Grand Inga” would have a drop of 155 m.

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Fig. 10.3 The Congo River gradient between Banana at the coast and Kinshasa. Distances are measured from Banana at the Atlantic Coast. The current—and potentially future—Inga hydropower plants take advantage of the massive drop of the river between Gombe and the Bundi River. The figures—distances and elevations—are approximate as various sources quote slightly different numbers

two more, even grander powerhouses, have been proposed. Complete harnessing of Congo River at Inga, called the “Grand Inga Project” is considered to be the ultimate hydropower prospect in the World with a capacity of about 40,000 MW, substantially bigger than the Three Gorges Hydro Development in China, the largest project to date (Fig. 10.4).

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Fig. 10.4 Another manually driven whaler, with missionaries on their way to a post. Notice this time a white person at the helm, sitting. The vessel has several markings along the hull resembling a rudimentary Plimsoll Line. (Photo AP.0.0.4586, collection MRAC Tervuren; photo E. Verdick, 1905)

Part II

Early European Mapping of the Maritime Congo River

Chapter 11

The First Europeans Venture Up the Congo Estuary

Abstract Our exploration of the Maritime Congo starts with some history. Since the cataracts prevented the first European traders to travel further upstream, for 400 years after the Portuguese Diogo Cão “discovered” the mouth of the Congo, the white merchants traded with the Indigenous peoples along the Congo estuary. Nevertheless, most of them did not venture further upriver than Ponta da Lenha and only later in the nineteenth century, up to Boma. Everything changed in 1877 when H M Stanley arrived in Boma, not by sea, but from inland. He had “conquered” the cataracts. This endeavor eventually brought him in contact with the King of the Belgians, who in 1885 was allowed by the European powers to lay claim as the ruler of Central Africa. In 1908 Belgium, reluctantly, took over the Congo as a colony. Keywords Maxwell · Embomma · Ponta da Lenha · Stanley · Leopold II · Congo Free State Over half a millennium ago, the first European, Portuguese navigator Diogo Cão,1 sailed up the mouth of the Congo River. At the time Portugal had become a global naval power. Its intrepid mariners had discovered the Atlantic islands of Madeira, the Canary Islands, and the Cabo Verde Archipelago. More discoveries awaited their navigators further south. King John II, inspired by his great-uncle, Prince Henry the Navigator,2 surrounded himself with mathematicians and astronomers to be able to expand the realm of Portuguese colonial possessions. The goal was for its explorers to navigate further south along the West-African coast to eventually find a sea route to India: “The Spice and Gold Road” (Fig. 11.1) Therefore, in 1482 capitammor Diogo Cão left Lisbon, sailing the West-African coast further south than any European before him. After rounding Cape Lopez, just south of the Equator, he reached the mouth of a majestic river, called Nzere or Nzadi3

1

Diogo Cão (1452–1486) His name was anglicised to Diogo Cam or Diégo Câm in French. Henry the Navigator, Duke of Viseu (~1394 to ~1460) has been recognized as setting off the “Age of Discovery.” 3 Nzadi meaning “great water.” 2

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Fig. 11.1 The mouth of the Congo River as the European explorers sailed from Banana on the Atlantic coast to Mompanga—today Malela, and the nomenclature as they assigned to various riverside features

by the riverside dwellers. The Portuguese mariners would transmute the word into Zaïre. Starting a Portuguese custom, before he embarked on his voyage of discovery, Diogo Cão had several stone markers made which he now carried in the cargo hold of his caravel. These markers consisted of an engraved stone pillar or padrão and were meant to be erected on important promontories or headlands of the African coast, thereby claiming the hinterland for the Portuguese crown. As such Diogo Cão had one of his pillars, surmounted by a cross, placed on the southern headland4 of this mighty river. Three years later, after a triumphant welcome in Portugal, Diogo Cão returned to the Zaïre River to sail upriver, as far as his three ships could take his expedition. This exploit took him over 150 km [93 mi] inland, to the first rapids that blocked his path further upstream, the Kasi cataracts.5 As a reminder for future generations, he left his mark inscribed in a large stone, still visible today. This fifteenth-century voyage had three major consequences for the further history of the Maritime Congo River: a political one, a commercial one, and a religious one. On the religious side, it marked the start of the Roman-Catholic endeavors of evangelization of the Lower Congo region. This path is today mostly

4 5

Which he called “Ponta Sancto Antonio.” The Kasi cataracts today are some five kilometres [3 mi] upstream from the Port of Matadi.

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The First Europeans Venture Up the Congo Estuary

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of interest to the historian who studies the early history of the “Kingdom of Kongo”6 and the neighboring lands of the estuary. Such scholars depend on the writings of European missionaries who, from the sixteenth century on, recorded the oral history of the Indigenous peoples. Economically it marks the beginnings of trade of Portuguese and Flemish merchants with the native peoples and the establishment of colonial wholesalers—like the Ximenez family from Antwerp, the port city that would become the pre-eminent European port for the shipping trade with the Congolese seaports. We will encounter the early white factories along the river. And then there is the political environment, a fact that has managed to establish itself on a permanent basis along the maritime section of the Congo River. Around 1610 the Belgian merchant Pierre van den Broeck, future Admiral of the Dutch East-India Fleet, established a trading post on the Congo shores. As the cataracts prevented Europeans from traveling further upstream, for 400 years, trading with the Congolese kingdoms was confined to the riparian lands of the maritime section of the river. In 1701, British merchants established a factory at Binda (Vindi la Nzadi, upstream from Boma), but it took another century before, in 1793, the British Captain Maxwell made the first purpose exploration of the Congo estuary, up to the cataracts. It was Maxwell who gave several physical features bordering the Lower Congo a name that endured into colonial times and beyond: Shark Point, Bulikoko Island, Scotchman’s Head, Henderson’s Head, Fetish Rock, Three Sisters’ Islands, Diamond Rock . . . (Fig. 11.2)

Fig. 11.2 The river between Mompanga in the west and Boka Embomma—today Princes Island— in the east. This is the Congo inland delta, an ever-evolving, natural region that we will look at in detail later in this book

Written “Kongo” to distinguish from the present-day Congo. The Kingdom of Kongo was a historical region generally seen as encompassing the lower Congo River and the northern part of Angola. 6

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In the Age of Sail7 there was no immediate scientific incentive to explore the reach of the Congo River beyond Ponta da Lenha (Woody Point or Point of firewood), 35 km [22 mi] upstream from the ocean. From a nautical point of view, sailing ships traveling the west coast of Africa did have plenty of protective bays along the central African coast to shelter from inclement weather. From north to south, the main natural bays in the vicinity were Pointe Noire (Black Point), Malembo and Cabinda, north of the mouth of the Congo, and Ambrizette (today N’zeto), Ambriz and (São Paulo da Assunção de) Loanda, south of it. If necessary, on the Congo mouth itself, mariners could retreat behind the spit of French Point, in the Banana Creek. It is no wonder then that the first bathymetric soundings upriver were made by the odd naval vessel of the Royal Navy, traveling just up to where the river split into three main channels, or “rivers” as they were called at the time. Here lay the white settlement of Ponta da Lenha,8 the point from where sailing ships did not dare to venture further inland. For an experienced mariner, sailing up to Ponta da Lenha was easy. The navigational risks were minimal, and the price was worth it: picking up slaves for the colonies of the European powers in the “New World”. Sailing upstream, against the often-strong current, was feasible as the river here was straight, with few sandbars. Shallows could be detected by an experienced lookout in the crow’s nest. Even if the wind were not out of the right corner, ships could beat against the wind as the river was wide enough to maneuver the vessel. This wide inlet was especially considered a “dark continent” and captains were always on their guard for a potential assault on their vessels. So, even when they were at anchor at Ponta da Lenha, they were ready to sail downriver at a moment’s notice, taking advantage of the strong currents to take them swiftly to open water, if necessary, even without the aid of the wind (Fig. 11.3). It seems that until 1876, when Robert Ivens9 travelled the river, past the first cataracts up to Isangila, no European explorer dared to travel further than the foot of the first cataracts.

11.1

Conquering the Cataracts

The European outlook on the region was turned upside down on the 9th of August 1877, when journalist Henry Morton Stanley10 arrived in Boma, not like every other European until then, from the Atlantic Ocean, some 100 km [62 mi] to the west, but

The “Age of Sail” lasted until about 1862 and was over by 1873. Ponta da Lenha: A white trading post, in the 1820s composed of some 16 bungalows. 9 Roberto Ivens, Portuguese explorer, geographer, navy officer (1850–1898). 10 Henry Morton Stanley (1841–1904), journalist and explorer. After being met with indifference and scepticism about the potential of his African discoveries in the United Kingdom, in June of 1878 Stanley found a willing ear with the King of the Belgians, Leopold II. An anecdote about 7 8

11.1

Conquering the Cataracts

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Fig. 11.3 The river from Princes Island in the west to Vivi (Banza Bibbie) in the east and the local names, as the explorers understood them from the Indigenous peoples

from the Indian Ocean, 2850 km [1771 mi] to the east, thereby becoming the first white person to travel downstream the entire Congo River. In Boma, Stanley discovered half a dozen factories, run by 18 Europeans. Stanley’s exploit was immediately front-page news in Europe and North America. To the colonial powers in Europe, it proved that the thunderous cataracts could be overcome and that between it and Lake Tanganyika lay a vast, still unexplored territory. Before Stanley arrived on the scene, European businesses had in general been trading with African merchants living along or close to the coast. The major European naval powers had limited themselves to patrolling the coastlines of the African continent to protect their white citizens and guard their commercial interests. Nevertheless, efforts were developing, by the British, French, and Portuguese powers, to venture further inland and colonize the territories they hence had “conquered.” This trend did not escape the king of the Belgians, Leopold II, a man who went about it on a grand scale.11 In September 1876 he organized the Conférence géographique de Bruxelles, also called the “International conference to discuss the means by which a well-planned exploration of Africa can take place.” In all, 11 European states had sent participants. At this international meeting participants

Stanley’s character goes like this: Upon setting foot on Belgian soil in Ostend, Stanley was met by an army officer, who welcomed him, bringing the king’s well wishes, whereupon Stanley immediately offered the man a tip. The officer, scandalously taken aback, vehemently refused. But Stanley retorted: “Please, accept, accept, every effort merits a reward.” 11 Leopold II (1835–1909), second King of the Belgians (1865–1909). Even more than his father he was convinced that Belgium needed a colony to ensure its industrial growth and provide room for settlement for its growing population. In Belgium he was the driving force behind many large-scale public works, initiatives he took to advance the kingdom’s economy and give his small country a place on the world stage.

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voted to establish an association with a so-called humanitarian goal, the Association internationale pour l’exploration et la civilisation de l’Afrique centrale, abbreviated as AIA.12 Because of the competing interests of the various powers, the society quickly fell apart,13 but 3 years later, out of its aches, Leopold II founded the Association internationale du Congo (AIC). Up to then, Central Africa had been avoided by white explorers, due to its impenetrable, wet, hot, but nevertheless luxurious landscape. Leopold II hence saw a chance to lay his hands on this enormous territory. At the same time Germany, under Otto von Bismarck, had likewise become interested in a piece of Africa. Aware of the rivaling European interests, Bismarck wanted to avoid a major conflict between the imperialistic countries and organized another conference, this time in Berlin at the end of 1884. Leopold II’s representatives at the gathering managed to bring home the international recognition for Leopold II as the private ruler14 over the territories of the Congo (River) basin, frantically being occupied by the AIC. The next step happened the following year when Leopold’s nucleus of Congo administrators (prematurely) named the new country l’État indépendant du Congo, or, as known in English, the Congo Free State (CFS). To explore and colonize his vast new territories, and at the same time fight the slave trade, Leopold II needed to spend vast amounts of money,15 an investment he wanted to recuperate through the sale of the natural resources of his newly acquired, private domain. That in turn led to widespread abuse of the Indigenous peoples by the white agents who earned a commission on the harvested resources. After an international outcry, the Belgian government in 1908 reluctantly took over the CFS, thus turning it into a Belgian colony. Fifty-two years later, in 1960, the colony gained its independence as Congo-Leopoldville, later Congo-Kinshasa. In 1971 Congo’s president Mobutu renamed the state Zaïre, after the ancient name variant of the Congo River. Finally, in 1997, with the ouster of Mobutu, Congo’s leaders renamed the country the Democratic Republic of the Congo (DRC). This, concisely, is an overview of Central Africa’s post-contact history that will better situate the successive stages of the hydrography and the navigability of the Congolese waterways. At first sight, looking at a map of Africa, the DRC looks like a rough square, with a little appendix on the western side. If it were not for this appendage, the country would be a landlocked state. Through this narrow land and water corridor, the

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AIA: International Association for the exploration and the civilisation of Central Africa. The commission established during the conference only met once, in 1877, the year that Stanley reached the Atlantic Ocean. A year later Leopold II, with the help of various investors, set up the Comité d’études du Haut-Congo (CEHC), a commercial enterprise to pave the way for private exploitation of Central Africa. The Committee hired Stanley on a five-year contract. The next year already the company went bankrupt, and Leopold II took all the reins through the new AIC. 14 Leopold II could only become the ruler of another country than Belgium upon the formal approval by the Belgian Parliament, which happened in April 1885. 15 As an example, in the Kouilou-Niari expeditions, Leopold II invested five million Belgian francs, an extraordinary amount of money back then. 13

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Conquering the Cataracts

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country has vital access to the world’s oceans and can export and import worldwide on its own terms. From the moment King Leopold II had laid his eyes on this vast inland territory, it had been recognized that this green lung of Africa, to economically prosper, needed its own access to the sea. What would be more natural for Central Africa than to trade via the mouth of the Congo River. Yet, before the Berlin Conference of 1884, it looked as if this was not going to happen.

Chapter 12

The Kouilou-Niari, an Alternative Access?

Abstract As initially Portugal adamantly laid claim to the mouth of the Congo River, Leopold II looked for an alternative outlet to the Atlantic Ocean, north of the Portuguese claim. He organized various expeditions into the area, then known as the Loango Coast and which is now part of Congo-Brazzaville. As a result, Britain and France finally persuaded Portugal to share the mouth of the river with the Congo Free State. As the German geographer Pechuël-Loesche had written in detail about the Loango Coast, Leopold II later contracted him to explore the High-Congo, an endeavor others deemed him incompetent for. Keywords Kouilou · Niari · Chiloango · Cabinda · Pechuël-Loesche · Mikic J · Grant-Elliot J · Van de Velde L · Hanssens E · Harou V North of the mouth of the Congo River two other historic rivers empty into the Atlantic Ocean. The first one, 100 km [62 mi] to the north, is the Chiloango River. Today it is the longest river in the Angolese enclave of Cabinda. Forty kilometers [25 mi] inland it becomes the border between the Angolese enclave and the DRC. But 100 km north up the African coast, another major river reaches the ocean: the Kouilou.1 Today it is the main coastal river of Congo-Brazzaville. Both lay in the region that explorers at the end of the nineteenth century called the Loango Coast, after the Kingdom of Loango, a pre-colonial, coastal state. As both rivers descend from the highlands on the western side of the Crystal Mountains, they are noticeably short as compared to the Congo River. The German geologist Dr. Pechuël-Loesche, whom we met earlier, described the local hydrographic conditions as follows:

1 In most historic Belgian literature “Kouilou” is written as “Kwilu” or sometimes “Kuilu.” But that orthography does create confusion with the other Kwilu River, a major tributary of the Kwango River in the Kasai region of the DRC. Hence, I utilize the current, French language “Kouilou” for the river in the Congo-Brazzaville country.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_12

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Being the southern border of the Loango Coast, the Congo is the only river that is navigable by ocean-going vessels. Even the largest ones can reach Ponto [sic] da Lenha. Those that have a draught of not more than seven to ten feet [2.1 to 3.5 m] can reach Boma. In the protection of the headlands on either bank of the river are good anchorages. On the right bank, towards Banana where the Dutch company called “Afrikaansche Handelsvereeniging”2 has its headquarters, one can find the only harbour worth of that name along the Loango Coast, where sailing vessels and steamers can easily load or unload their cargo. To aid sailors in their orientation the named company has installed buoys and beacons in the river mouth. This has significantly simplified the complicated maneuvering of sailing vessels in the wide estuary. On the southern shore, near Shark Point, one can normally notice one or the other British warship at anchor that has been tasked with patrolling the west-African coastline. Apart from the Congo River, only two other bays along this flat coast provide shelter for deep-draught vessels: the one at Yumba and the one at Pontanegra [Pointe Noire]. Within the Pontanegra Bay ships have ten to eight fathoms [18 to 14.5 m] of depth. At Yumba Bay, which is better formed and roomier, ten to six fathoms [18 to 11 m]. ... Both bays nevertheless give little protection against the sea swell. The mouth of the actual rivers on the Loango Coast are inaccessible to large ships on account of the shifting sandbars making for variable depths. Small steamers with five feet [1.5 m] draught can enter the Chiloango River and reach Chiume. Once a coaster with ten feet [3 m] draught managed to cross the sandbar in front of the Kouilou River but only reached Real Island.3 Waiting for high tide, large steam launches can reach the Kouilou, Loémé and Chiloango river mouths and navigate upstream until about halfway towards the mountains. These, for inland travel important waterways along the Loango Coast, are, up to now [1882] only used by canoes and the odd boat. As far as one can establish, these voyages are smooth and swift. The big difficulties only start when one, at the foothills, reaches the point where one must transfer to overland travel in the mountains. The farther inland the foothills are, the easier it becomes to explore the interior.

Güssfeldt, the leader of the German expedition, described the mouth of the Kouilou as 375 m [900 ft] wide. A large sandbar blocked any sea-going vessel from entering the mouth. An old factory that stood on the north bank of the mouth was washed away in 1868. Subsequently Güssfeldt, with the aid of 12 paddlers, rowed upriver. Undoubtably, Pechuël-Loesche’s exhaustive narrative on the Loango Coast came to the ears of King Leopold II and the German geologist was invited to Brussels to meet with Colonel Maximilien Strauch,4 Leopold II’s senior Congo advisor. The reason was simple: a major European storm was brewing against Leopold’s aspirations in the Congo Basin. Portugal’s territorial claims, being tenuously established along the African west coast from the Loango Coast southward, threatened the logical choice for the AIC to get access to the sea through the Congo estuary. Since Great Britain initially supported Portugal’s claim, there was no other way 2

Afrikaansche Handelsvereeniging: African Trade Association. Real: Until 1911 official currency of Portugal. Pechuël-Loesche uses the German designation, Reïs. 4 Maximilien Charles Ferdinand Strauch (1829–1911), originally infantry officer, in 1878 nominated Secretary-General of the AIA. From then on, he was head of the small group around the king, solely tasked with the king’s Congo enterprise. Did not leave any notes about his negotiations surrounding the creation of the CFS. 3

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for Strauch & Co to find an alternative access to open water. That would have to be north of Portugal’s claim, which at the time reached up to the Chiloango River, in what today is Angola’s Cabinda Enclave. Partly due to the findings of the German Loango Expedition of 1875, it was thought that the upper reaches of the Chiloango and Kouilou rivers diverted towards the Congo River.5 In case the Portuguese could hold on to their claim in the European diplomatic power struggle, the only option left for Leopold II was to find a land corridor for his Congo territory from the Malebo Pool to the Chiloango and Kouilou rivers. Time was running out for the king of the Belgians, as French explorer Pierre Savorgnan de Brazza6 passed through the Loango region in April 1882, laying the groundwork for a French colony north of the Congo River. Literally circumventing the Portuguese claims now looked dicey as France would soon take possession of the north shore of the Haut-Congo, hence totally blocking an exit for the new Congo State. So, on January 15, 1882, the German geologist did receive secret instructions from Colonel Strauch in Brussels to return to Africa to, among others: Investigate if it is possible to open a road from the Stanley Pool [Malebo Pool] to the ocean above 5°12′. ... and if it would be possible to establish a good harbour ... 7

Consequently, Pechuël-Loesche returned to the Congo in early spring. But his dithering in trying to arrive in Vivi, Stanley’s headquarters at the foot of the Congo Cataracts, made this last one decide that the German scientist would be unsuitable to lead an arduous expedition into the mountainous region north of the river, towards the Kouilou-Niari rivers. Instead, he put British Captain John Grant-Elliott in charge of the expedition. Together with Destrain, Legat,8 von Schumann, Ruthven, and Illingsworth, the Brit left Vivi for Isangila, upstream from Vivi, on January 13, 1883, from where, 10 days later, their expedition into the Niari basin started. They were accompanied by 70 Zanzibari soldiers. Their task was to sign alliance treaties with the local chiefs, establish stations along the Niari River and descend it to the coast. After 23 days they reached the Niari River where they established the post of Stéphanieville.9 Destrain stayed behind to run the station. Next, where the Niari

5 Das Gebiet der Internationalen Kongo-Gesellschaft - Petermanns geographische Mitteilungen (1884). 6 Pietro Paolo Savorgnan di Brazza (1852–1905). Italian-French explorer. 7 5°12′ [South] is the mouth of the Chiloango River. If Portugal would have managed to establish its claim from Angola in the south up to that latitude, then the CFS would have been cut off from the Atlantic Ocean. 8 John Grant-Elliot (1837–ca. 1888), Captain of the British Army. Édouard Destrain (1854–1890). Left Antwerp in May 1882, under contract with the Comité d’Études du Haut Congo, a commercial organisation, also set up by Leopold and lead by Col. Strauch. Alexandre Amedée Legat (1860–1898). His first tour of duty in the CFS lasted an astonishing 12 years (1883–1894). 9 After Princess Stéphanie (1864–1945), daughter of Leopold II, who married Austrian Crown Prince Rudolf (1858–1889) in 1881. Rudolf in turn got his own post named after him shortly after.

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Fig. 12.1 CFS Posts founded in 1883 and 1884 in the Kouilou-Niari region

became the Kouilou, a second post was established—Frank-town—where Legat stayed to run the station until November 1884 (Fig. 12.1). Meanwhile, to make sure that the Kouilou-Niari expedition would not fail in its goal, Stanley had set up a second expedition, this one under the command of Belgian Captain Liévin Van de Velde. With Janko Mikic and Dragutin Lehrman10 and accompanied by 10 Zanzibarite soldiers, an interpreter, and 10 African sailors, Van de Velde left Vivi 12 days after Grant-Elliott and arrived on the Atlantic coast at the mouth of the Kouilou River on the 16th. Two days later Van de Velde signed a treaty with the local chief, giving Leopold’s Congolese association possession of the left (south) bank of the lower part of the river. On February 25th, the group turned a former factory into a European station called Rudolfsstadt and Van de Velde marched 45 km [28 mi] further upstream, then returned. A few days later the French battleship Sagittaire, arriving from Loango, found that the Belgians had beaten the French to the Kouilou. On March 14th, Van de Velde got word that a column of white people had gotten in trouble further upriver, near Kibati. Accompanied by Mikic, Van de Velde 10

Liévin Van de Velde (°Ledeberg, 1850–1888). During the Berlin Conference and the founding of the CFS, secretary to Col. Max Strauch. Janko Mikic (°Karlovac, Croatia, 1856–{ Austin, TX, 1897). Lieutenant in the Austrian Army. Accepted in the AIA in November 1882 as a lieutenant on a 3-year contract. In 1884 chief of the Baudouinville Station. Dragutin Lehrman (°Pozega, Croatia, 1862–1918).

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paddled upstream to their rescue. Meanwhile, he set up a post he called Baudouinville11 where he left Mikic in charge. On April 5th, he met up with the distraught whites, being the column of Grant-Elliott. They were all weakened by fever and illness. Two of Grant-Elliott’s companions (Ruthven and Illingworth) had been left behind further upstream and Van de Velde sent for their rescue, and they were carried back to Baudouinville in hammocks. While Mikic took care of them, Van de Velde and Grant Elliott returned to Rudolfstadt on the coast. A while later Mikic continued his exploration of the Kouilou region, backtracking toward Boma. On his return to Rudolfstadt, and still south of the Chiloango River, he signed treaties with 15 local chiefs. Sometime later Mikic and Lehrman returned to the Kouilou-Niari watershed and traversed it from West to East, finally arriving at the Stanley Pool, via the Djué River. Their detailed notes, taken during their difficult journey, complemented those made earlier by Eduard Destrain. In the end, due to international diplomacy, the northern part of the region had to be ceded to France, while some of the southern parts became the district of the Bas-Congo of the CFS (Fig. 12.2).

Fig. 12.2 CFS contracted explorers’ routes through the Kouilou-Niari region in search of an alternative access to the ocean for the CFS

11 After Prince Baudouin of Belgium (1869–1891) at the time of his birth second in line to the throne, then held by Leopold II, his uncle.

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A third expedition, led by Belgian Captain Hanssens, was tasked to find a suitable land and river corridor along the Kouilou and Niari Rivers. This was to be a delicate mission, as the lands north of the Kouilou had already been ceded by the local Betake chiefs to French explorer de Brazza. Hanssens, accompanied by Lieut. Harou,12 left Manianga on February 23, 1883, a month after John Grant-Elliott, and they made their way, dead reckoning, through dense tropical forest toward the Niari River. With scanty food supplies, 4 days later they reached Stéphanieville where they met up with Destrain. Following the Niari River upstream, they establish the post of Philippe-ville, at the edge of the territories already conceded to de Brazza. Being wounded during an attack by Indigenous people, Hanssens returned to Manianga and descended the river to Boma. He then returned to the upper Niari to sign treaties with the local chiefs and sets up the Mukumbi station. In essence, the overarching goal of these pre-CFS Niari expeditions was to use the region as a bargaining chip in the negotiations with the other colonial powers, Great Britain and especially France, to have them pressure Portugal to relinquish its claims on the mouth of the Congo River. Eventually, the Portuguese caved in.13 At the Berlin Congress of 1884, the Kouilou-Niari River basin came under French control while the Cabinda territory stayed Portuguese, and the north bank of the so important Congo River became part of the CFS. King Leopold II triumphed in his diplomatic battle for the mouth of the Congo River (Fig. 12.3). While the mouth of the Kouilou River did not provide for the establishment of a deep-water port, further south the bay off Pointe Noire would have been a desirable choice. The French did build a port there in 1924 and 10 years later had it connected via rail to the capital Brazzaville (see Fig. 10.1). That the Belgian explorers were looking for a similar solution can be deducted from one of the early Kouilou sketches [Hansen, JAA, Carte des itineraries du Capt. Hanssens, des lieut. Harou et Mikic en 1883 et 1884] where, between Isangila and Mbeki Songho the “Rudolfs’ Hills” and “Stéphanie Valley” are mentioned. The major drawback of this scheme was of course that any Free State railway would still have to cross the Congo River, somewhere in the cataracts’ region. If the Stéphanie Valley is any indication, then it could be assumed that the officer who named this valley, saw it as a corridor for a potential railway, coming from the coast north of the Cabinda enclave and running

12

Capt. Eugène Hanssens (1843–1884). Arrives in Banana on March 5, 1882. January 1883, Stanley returns unexpected to the Congo and puts Hanssens in charge of the Lower Congo, including the Kouilou-Niari basin. Victor Harou (1851–1923). Arrived in Congo in October 1880, returned finally to Europe in September 1884. 13 In 1883 the Portuguese Geographical Society put out a 104-p. detailed statement as to the “Rights of Portugal” to the mouth of the Congo. It listed at least four main reasons: (1) Claims due to the law of nations, (2) The rights as a discoverer, (3) The rights resulting from possession and (4) The rights defined in treaties.

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Fig. 12.3 The Kouilou-Niari region and the present-day borders

towards Isangila. Since the Isangila-Manianga reach of the Congo River to a certain extent is navigable, it would have been possible to transship goods at this post, run it upriver to Manianga and there transship it again on a railroad, this time on the south bank of the river, towards Kinshasa. As we have seen, that was one of the alternatives discussed when the railway from Matadi to Kinshasa was in the planning stage.

Chapter 13

The Voyage from Europe to Congo

Abstract The sea voyage for Belgians to the Congo was initially a long and uncomfortable journey. As passengers’ numbers and cargo in the early years of the CFS were small, only occasionally a foreign vessel would stop at Banana. Later, and only briefly, three small Belgian steamers would call on Banana. From 1892 on British and German vessels agreed to regularly stop in the Belgian port of Antwerp to take on passengers and cargo destined for Banana and Boma. Finally, from 1911 on a newly established Belgian company would open a regular, scheduled connection between Antwerp and the meanwhile Belgian colony with its own vessels. By 1914 four European shipping lines made regular stops at the Congolese ports. Keywords Banana · Elder Dempster · Compagnie Belge Maritime du Congo · Congo Boat Tuesday, 23rd of June 1885. On board the steamer Afrika: At 11 o’clock we see the coastline and, approaching, I recognize the red cliffs north of Shark’s Point. We sailed too far south and missed the Congo estuary. I keep my mouth but internally I enjoy the other passenger’s bewilderment when they look at their compass needle. We turned north! It was indeed Padrão Point I had seen earlier. We turn the cape and I notice a sailing vessel anchored near Shark’s Point. Here we are at the mouth of the great Congo River; coffee-and-cream coloured sea water, with that smell of decomposing plant matter, accompanied by a greasy froth of diatomaceous earth. A leaden sky, a tea-like sea, a black coastline bordered by a thin white surf. One, two, three, then an entire line of whitewashed shacks, with a few flagpoles scattered about: it is Banana, over there, left on the horizon.

Liévin Van de Velde, « Le Bas Congo, I. Banana », in Le Congo Illustré, 1892. For a Belgian explorer, in 1874 it would take over 2 months from Lisbon in Portugal to reach Saint Paul de Loanda in Angola on board a Portuguese threemaster sailing ship. From there passengers for the Congo still needed to transfer to a smaller vessel that travelled the coastal waters to return the 300 km [186 mi] north to Boma.

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When in 1879 the Comité d’études du Haut Congo1 was founded, only two British shipping companies operated along the west coast of Africa: The British South African Steam Navigation Co and the African Steamship Co. Both worked out of the Port of Liverpool and coordinated their departures so that a ship would leave the United Kingdom every 6 weeks. The Committee would either book cargo space on one of these vessels or charter a freighter. From 1883 nevertheless the Portuguese shipping company Empreza Nacionale would have a vessel call at Banana from time to time. The CEHC arranged with the Portuguese to have one of their vessels, bound for Africa, to call at Antwerp once every month. Though, it turned out that the vessel concerned, after leaving Antwerp, made a 15-day stop at Lisbon. The trip southbound thus took 45 days.2 By 1887 three small Belgian steamers, the Vlaanderen, the Lys, and the Brabo, owned by the Compagnie Gantoise de Navigation from Ghent were the first and only Belgian vessels plying the waves between Antwerp and the Congo. All three measured 1650 tons and had inadequate passenger accommodations, but they made the voyage in 24 days. Unfortunately, while southbound freight covered the expenses, return cargo was still scarce and the following year foreign competition torpedoed the enterprise. Until 1892, no regular shipping line would call on the Congo estuary. Steamships of the English Elder Dempster Line, on their regular route from Liverpool to Saint Paul de Loanda, would stop at Banana occasionally, if cargo were to be dropped off or picked up at this lonely spit of land. Eventually, after long negotiations, it was agreed that these steamers would include Banana as an intermediate halt, every 6 weeks. But it required Belgian cargo to be transshipped in Liverpool and, at Banana, still needed to be brought upriver to Boma or further inland. In total it would take almost 2 months for goods to reach Vivi, and later Matadi.3 Then after 1892, an Elder Dempster steamer would pick up cargo in Antwerp on its way to the African west coast. The vessel would call on Banana, Sicia,4 Boma, or Matadi as requested by the shipper and travel time was reduced to 24 days southbound, 30 days northbound. A similar agreement was reached with the German Woermann Line. The contract stipulated that on the return voyage, these steamers were to call on Antwerp to drop of passengers, but they were to continue to Liverpool or Hamburg with their valuable African cargo. So, the call for a Belgian shipping line quickly grew.

1

Comité d’études du Haut-Congo: CEHC, Study Committee for the High-Congo. Founded by Leopold II in 1878. 2 Georges Paget Walford (1892), in Le Congo Illustré, p. 201. 3 First post at Matadi in 1885. In 1887 the decision was taken to build a railway from Matadi to Léopoldville. By 1892, 300 whites, and over 3000 Black people were living in Matadi. The first ocean-going vessel to venture beyond Boma and reach Matadi was the Lualaba of the African Steamship Co. (20th of June 1889). 4 Then a station on the west coast of the Grand Island of Mateba.

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Eventually, by 1911, a proper Belgian connection between Antwerp and the Congo was functioning. Three large vessels,5 owned by a newly (1895) established Compagnie Belge Maritime du Congo (CBMC), offered comfortable passenger travel to and from the now Belgian colony. Up to the First World War, four steamship lines called on the maritime Congo ports. Two of them, the Belgian CBMC and the French Chargeurs réunis, by 1912 had agreed on a combined schedule whereby a mail steamer would call at Boma every 10 days. These two would monopolize passenger traffic since the Germans and Brits only ran cargo vessels. Portuguese ships would only occasionally show up, while Dutch coastal vessels were engaged in coastal traffic. During the war, four CBMC vessels that had escaped the port of Antwerp prior to the German occupation sailed to Boma from the English port of Hull, and called at Bordeaux on the return trip. In the year before the war (1913), 35 Belgian steamers had called on Boma and 17 at Matadi. The same number of British vessels had moored at both ports, but their cargo handling was about one-third of that of the vessels flying the Belgian flag (Fig. 13.1). Since in the early days Boma was the capital of the CFS,6 most steamers would not venture further upstream, so the AIA needed not only a small steamer to ply the

Fig. 13.1 The (second) SS Elisabethville of the CBMC, built in 1921. Here she is pictured off Casablanca, on her way to Matadi, in 1923. During her career she made 98 trips to the Belgian Congo. The first Elisabethville had been torpedoed in 1917 by a German U-boat. These so-called “Congo Boats” were extremely comfortable for their time. (Devroey Family Archive)

5

The Bruxellesville 2 (5100 LT), the Léopoldville 3 (5150 LT) and the Elizabethville 1 (5695 LT). The same year they were to be joined by the Anversville 2 (7480 LT) and the Albertville 4 (5062 LT). 6 Boma would continue to be the capital of the Belgian Congo until 1923.

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Bas-Congo between Banana, Boma, and Stanley’s headquarters in Vivi, but it also needed a steamer to work the intermediate cataract stretch between Isangila and Manianga. These vessels needed to have a cargo capacity of 20 tons. Pechuël-Loesche estimated that the sea-going coastal steamer should have a draught of only 1.2 m [4 ft] in order that it would clear the shoals in the estuary and that it would be able to dock at the local piers. In total he expected this ship to make seven trips a month between Boma and Vivi, thereby moving 140 tons of goods either way. Exceptionally, the vessel would have to pull a barge or two along. Finally, the ship would have to be seaworthy so that it could make short coastal trips to outlying trading posts. Having two masts would allow it to sail when weather conditions allowed, which would save on coal.

13.1

Belgium Takes Over the Congo

After multiple scandals had been exposed by the international and Belgian press about serious mistreatment of Congolese people under the personal rule of the King of the Belgians, the Belgian parliament in the fall of 1908 voted in favor of taking the CFS away from the king and rule the Congo as a colony. It was hoped that that would bring democratic oversight of running a vast territory, 6000 km [3730 mi] removed from Belgium and 76 times larger. An enormous undertaking for a small country. That the maritime access to its colony was uppermost important to Belgium is highlighted by the fact that in 1909 the colonial government, still headquartered in the capital of Boma, was comprised of eight directorates. While the First Directorate was that of the Secretary-General, the second one was that of Marine & Public Works, before any other department.7

7

Directorates are comparable to ministries or departments today. The third Directorate were Administrative Services, fourth Army & Defence, fifth Justice, sixth Finances, seventh Cadastre (Land Titles) and eighth Agriculture & Public Lands.

Part III

The Hydrography of the Maritime Congo River

The braided section of the Maritime Congo River is one of the most complex fluvial systems in the world but, over a century, a wealth of experience, has been accumulated. (Jean-Jacques Peters)1

1 Jean-Jacques Peters ({ 2012) was a Belgian Hydraulics Engineer, professor at different universities and a consultant for many international institutes all over the world. His great pride nevertheless was his years of work on the Lower-Congo River.

Chapter 14

Introduction to the Bas-Congo

Abstract With this chapter, we enter the detailed hydrographic study of the maritime section of the Congo River. First, we describe the general climatological conditions of the Bas-Congo, the population distribution, the various soils, general vegetation, and discharge characteristics of the river. The Congo River is unique in the sense that it crosses the equator twice, thereby producing two high water and two low water seasons in its lower reach. This has a few advantages: it stabilizes the potential hydroelectric output from the river, and it dampens water level variations in the system, thereby aiding in river navigation year-round. Keywords Kongo-Central · Mayumbe · Congo River discharge · Khokhloff A Our steamer has halted at Banana, so our captain can pick up the messages that have been left here for him. Upon his return the vessel resumes its voyage and passes Ponta da Lenha. From here on the flora changes, the brackish water and the mangroves disappear. Instead, numerous islands, made up of dark and thick clay, are covered in a luxurious tropical vegetation of the richest kind. One notices the giant kapok tree, the baobab, the tamarind tree, intermingled with the oily palm and wild dates. Long lianas interlace the trees, and the underbrush is composed of dwarf palms, gigantic dracaenas, and ferns. Along the shoreline, underneath the overhanging branches, drift calamus, papyrus and all sorts of grasses. One cannot distinguish any ground where one could land without being forced to cut its way through with an axe or a machete. Green pigeons, screeching parrots and monkeys make this intricate pallet of green come to life. From time to time a narrow channel, a clearing of compacted soil and the large leaves of a few banana trees reveal the existence of an indigenous village: tiny huts, covered with dried leaves, next to giant trees. (Capt. Liévin Van de Velde in Le Congo Illustré. De Banana à Boma. p. 86. 1892)

14.1

Climatological Observations

The region of the Maritime Congo River between the Atlantic Ocean and the city of Boma enjoys an average daily temperature of around 30 °C with a 26 °C low in July & August and a high of 33 °C in March. Being close to the ocean, the relative

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_14

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humidity is high, on average between 75% and 80%. Even in the dry season the humidity drops only by 10%. The prevailing wind blows out of the WSW to SSW and can be quite strong, especially for 3–4 hours after sunset. As for precipitation, the winter months—beginning in October, through January—are wet, with January reaching over 200 mm. The annual amount of rain along the Maritime Congo can reach between 800 and 1000 mm1 while Matadi, further inland and between the mountains, only gets 100 mm a year, on average. In the rainy season, sudden downpours can cause temperature drops of 7–8 °C within 15 minutes. The summers are dry, with no rain from the 15th of May to the 15th of August.

14.2

Population of the Kongo-Central Province

The Maritime Congo River today falls under the authority of the province of “Kongo-Central.” As such, this is the only province in the DRC with a coastline. It is better known outside the country as Bas-Congo, or in English, “Lower-Congo.” The provincial capital is the port city of Matadi, at present having some 300,000 inhabitants (in 1950 it was 40,000). The only other city is Boma with 170,000 residents (15,000 in 1950). The province has four districts: Boma, Bas-Fleuve, Cataracts, and Lukaya. Other large communities are Mbanza-Ngungu (formerly Thysville) with about 100,000 residents (10,000 in 1950) and Moanda on the coast, with a current population of 90,000 (Fig. 14.1).

Fig. 14.1 The province of Kongo-Central—formerly Bas-Congo—with its main urban centers

1

That is as much as New York City gets but spread over 9 months instead of 12.

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Vegetation Along the Maritime Congo

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The Top Soil

In the Lower-Congo one encounters four types of soil: 1. Sandy soils with less than 20% of clay in the top 1 m [3.3 ft] layer. These are medium soils that are not suitable for agriculture but can be used for grazing livestock. One example is the area north of the Mateba Grand Isle. 2. Sandy clay and clay soils. They belong to the ferrallisols, red or yellow soils of the humid tropics, on basic rock. The more to the west, these soils are more sublittoral cretaceous sandstone. These types of soils are mostly found around Lukula, Tshela, north and northwest of Seke-Banza. They are medium fertile, except in the sandy areas to the west. 3. The clay-sandy soils can be found south of Seke-Banza, southwest of Luozi. Mbanza-Ngungu (except to the northwest), Madimba, and the Inkisi valley. Texture is clayey-alluvial, quite fertile, except south of Mbanza-Ngungu where the soil is more composed of fine sand. 4. Sandy-clayey soil with spots of clayey sand, north and east of Luozi and northwest of Mbanza-Ngungu. These topsoils are fragile and a poor growing medium.

14.4

Vegetation Along the Maritime Congo

When one enters the mouth of the Congo River, past the Bulabemba lighthouse, both banks are lined with thick and majestic vegetation, practically consisting exclusively of mangroves. They grow in the alluvial zone, up to 30 km [18.6 mi] inland, and are formed by a multitude of muddy creeks. The mangrove region on the north bank, the Congolese side, is 10 km [6 mi] wide. Since 1994 the mangroves form part of the DRC’s Mangroves National Park, which covers 66,000 ha [163,000 acres], of which 20% is water.2 It forms immense fields of papyrus in the swampy areas, mangroves, and reed palms in inextricable tangles in the brackish creeks within the tidal range. Immediately to the north of the mangrove forest, and parallel to the coast at some 7 km [4.3 mi], lies the 100–140 m [325–460 ft] high, sandy Moanda Plateau, 3–4 km [1.8–2.5 mi] wide.3 It has a tropical steppe vegetation and reaches up to the Banana Creek in the south. Past the Malela Cove,4 some 11 km [7 mi] upstream, the mangrove narrows to a few thousand meters [3300 ft] as the higher Kesa Vungu plain—so-called on the

2

The Park is located between 5°45′ and 6°05′ latitude S and 12°45′ and 13°00′ longitude East. The Park is a Ramsar Site No. 788. 3 In the 1950s the Belgian Air Force built an air base (Kitona) on the plateau. Today the airfield is deserted. 4 The Malela Cove consists of a local widening of the river. The shore line at this point is protected by an ever-shifting sand bank on which islands will appear and then get carried away again during flood season.

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map of 1901—from the north closes in on the river. Here the river widens but large islands start to dot the stream. To the left one passes Ponta da Lenha, historically a group of French and Portuguese factories (1891). Today only the small settlement of Katala remains on the island. The river splits here into three branches: on the south side, along the Angolese coast, it used to be called the Rio do Sonho or Portuguese Pass. Then there is the Mateba Pass in the center, through which the still undefined Angolese-DRC border swings and north of the Grand Island Mateba meanders the Luango Channel. From Katala on the vegetation changes. The river and its many tributaries and channels are lined with gallery forests with a varying degree of African Elaeis (oil) palm trees (Fig. 14.2). These trees form clusters of palm nuts in their canopy, 80 cm to 1 m [2.5–3.3 ft] long. On the higher and drier grounds, savanna appears, dotted with scraggy shrubs, or entirely grassy.

Fig. 14.2 An oil palm or Elaeis tree (1923). Compare the size of the tree with the human at the foot of the trunk. (Devroey Family Archive)

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Vegetation Along the Maritime Congo

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The large plains are dotted with palmyra palm (Borassus aethiopum or akeassii) with their characteristic protuberance near the top, baobabs with their broad trunks and doum palm (Hyphaene guineensis) or Borassus.5 Past the Kesa Vungu plain, further inland, along the northern arm of the river, patches of marshland are separated from each other by hilly terrain with an average height of a 100 m [330 ft] or more. On one of those higher tongues that reaches to the Luango Channel lies the Zambi settlement. Further east the Lukunga River empties in the Congo. It comes from the north and winds its way through a wide, undulating plain with the lower parts made up of marches. To the north of Boma, the Lukula and Tshela regions called Mayumbe, are covered with forest, an extension of the Gabon Forest to the north. In colonial times a 140 km [87 mi] long, narrow-gauge railway connected Tshela via Lukula to Boma. Being close to a seaport, the Mayumbe district was a major producer of tropical fruits and lumber (Fig. 14.3).

Fig. 14.3 Diagram of the limnimetric observations between 1915 and 1954 at Boma and Matadi. Since no large affluents enter the Congo River between both cities, the discharge remains the same and only one graph suffices for both. Since observations in that 40-year period were not conducted on a continuous basis throughout the year, this is a compilation of observations over irregular time spans (years indicated). (After Khokhloff, 1964)

5 It has a small fruit of a dark colour, an irregular, cylindrical trunk and is know in the alluvial zone as “Matebbe.”

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The Congo River Discharge

The annual fluctuation of the Congo River discharge is marked by two high and two low water stages (See the diagram). A smaller flood stage arrives in April–May and is the result of the rainy season along the tributaries on the left bank of the Congo: the most important being the Kasai, the Lomami, and the Lualaba (Upper-Congo) river systems. These rivers get their water from the southern hemisphere. The larger flood season occurs in November–December which is triggered on both hemispheres. A large drop of the water level occurs in July–August during the dry season in the southern hemisphere, where most of the Congo watershed is located. However, since the Congo River sits astride the Equator the minimum discharge figures of the river (August) and the highest discharge in December are tempered by one-third, or sometimes even halved, in average years. This phenomenon is unique compared with other large rivers on the planet. It not only facilitates river navigation throughout the year, but it also stabilizes the potential hydroelectric output of power stations along the lower river (today only Inga I & II in the Cataract region generate electricity directly from the Congo River) (Fig. 14.4).

Fig. 14.4 A detail of the mangrove forest in the intertidal zone between Banana and Malela. (Devroey Family Archive)

Chapter 15

Early Maps of the Maritime River

Abstract We first discuss the making of the earliest charts of the Maritime Congo. From Maxwell, through Tuckey to the HMS Rambler, the first nautical charts were a British affair. Then, in 1881 Charles de Rouvre gave a good description of the Congo estuary, up to Boma. At the entrance to the Congo, the river has a depth of already 300 m, quickly descending into an oceanic canyon, but the most interesting part of the river, from a mariner’s point of view at least, lays just 30 km inland. Here the river forms an inland delta whose geographical features we describe in detail. From Boma to Matadi the river flows in a narrow channel, ending in Hell’s Cauldron, just downstream from Matadi. Keywords Tuckey · Fitzmaurice · Vidal · Medlycott · HMSRambler · Bulabemba · FetishRock · CongoCanyon · Mateba · Matadi · Hell’s Cauldron Today, in the age of global positioning systems and echo sounding, it is difficult to imagine that there was a time when hydrographers and land surveyors needed to spend weeks crisscrossing the various channels of the Congo River in small, rickety boats with their precious surveying instruments, setting up reference points and signals on muddy shores, locations from where they could oversee the mighty river and point their telescopes to the opposite side. The first European map to appear that dealt with the maritime section of the Congo River in some detail was the 1816 “A Chart of the River Zaire” by Royal Navy Captain James Hingston Tuckey & R. N. Master & Surveyor Lewis R. Fitzmaurice. Tuckey had been dispatched by the British government to survey the Lower Congo River, to verify the conjecture of Mungo Park, a Scottish physician, who in 1805, had descended the Niger River past Timbuktu and speculated that the Niger River emptied in the Atlantic Ocean at Banana. The whole affair originated in the fact that an Arab merchant along the Niger River had called the river “Zadi,” while, according to Maxwell, in the Congo cataract region the locals called the Congo River “Enzaddi” while Tuckey understood in Boma the river was called “MoienziEnzaddy.”

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_15

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Tuckey’s expedition was the first scientific endeavor to reach beyond the cataracts and venture to find the source of this mysterious river. In that goal the mission failed, as Tuckey and 16 of his crew and scientists died after they had conquered only the lower set of cataracts.1 As for the map Tuckey’s crew produced, the cartouche is telling: “A chart of the River Zaire. The lower part from the mouth to Embomma [Boma] corrected from Maxwells Chart and from thence to the Narrows at Nomaza Cove, surveyed by Mr. Fitzmaurice R.N. [Royal Navy], from Nomaza Cove to the extreme point explored from a Sketch by Captain Turkey. . .”. In other words, Tuckey based his chart, from Banana to Boma, on the survey made by the British captain Maxwell2 in 1793. For the river between Boma and the Nomaza Creek, at the foot of the first cataract, Fitzmaurice’s survey was used while the cataract region itself was depicted following Tuckey’s own observations. As Tuckey never made it past Isangili, in the following decades, Europeans assumed that the Congo River was not navigable in its upper reaches. According to Maxwell “the flow at the mouth of the Congo is evaluated to be 6 to 7 miles per hour [11 to 13 km/h], with a depth at mid-channel of 100 fathoms [182 m], continuing for 24 to 25 miles inland. At 50 miles3 inland, the river splits into many channels that reunite at a distance of 90 miles where the river width is 1.5 miles with depths of 30 to 50 fathoms. This width and depths persist to 130 miles from the river mouth.”

While Maxwell had sailed along the north channel—later named after him— Tuckey’s vessel hugged the south or Portuguese shore from Shark’s Point all the way to the Monolith and Boma. Once past this trading post he briefly reverted to the south shore but after a short while came back to the north bank until the sharp bend at Fiddler’s Elbow—now Muzuku Point—where his ship returned to the Angolese side. All along, for an exploring but cautious captain, this route was intuitively the safest navigation option: always stay on the outside of the bend, where stream depth can be expected to be the deepest. He deviated from that principle in the Palmyra Reach, most likely because the Three Weird Sisters, three rocky islets near the western shore, did not bode well from a navigating point of view. Then, between 1825 and 1826, the British captains Alexander Vidal and William Owen attempted more survey work in the estuary. On Christmas Eve of 1825, survey ship HMS Barracouta, a sister-ship of the more famous HMS Beagle, wanted to enter the mouth of the Congo River, but for six successive days could not make headway due to the strong current. Then, on New Year’s Day, a strong sea breeze allowed the ship to proceed. Some 46 km [29 mi] upstream, near Quiambe Head on the southern shore, the ship anchored. The Angolan shore was explored, as far as Palm Head, “...

1 After Tuckey and most of his crew perished from fever, Fitzmaurice took over command of the expedition. 2 Captain Maxwell sailed up to Musuku Point, 35 km [28 mi] upstream from Boma. Here the river makes a 90 degree turn and he aptly called the bend “Fiddler’s Elbow.” 3 It is not known if Maxwell refers to nautical [1.85 km] or statute [1.60 km] miles but certainly, his distances were quite exaggerated.

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the deep channel of the river being traced for 13 [nautical] miles above Cape Pillar.”4 Four days later the brig-sloop left the Congo, sailing up north along the African coast. For the next 22 years no notable European ventured up the river, until 1848, when the Hungarian Lieutenant-Commander Ladislas Magyar arrived in the estuary on a barge from Ambriz in Angola. After briefly visiting the slave trading settlement of Ponta da Lenha he returned to exploring upriver. Four miles from Ponta he recorded the river split in two branches, each more than a mile wide, encircling a 20 miles long island, called “Palm Island” or Ilha das Palmeiros in Portuguese. He meant the Grand Isle Mateba. After staying 2 days on the island, he reached Boma, a settlement of 50 dwellings. Persevering in his endeavor, he continued upstream until reaching the cataracts upstream from nowadays Matadi. There he got ashore and continued his remarkable voyage on foot, southeastward into the Kasai River basin and even further into the Zambezi system. Quite an amazing trek. In 1860 the British captain Bedingfield in turn sailed up to Boma in HMS Pluto, a ship with a draught of 3.66 m [12 ft] while 3 years later Richard Francis Burton went as far as the cataracts. Banana was visited in August of 1875 by the paddle-sloop HMS Spiteful under the orders of Captain Mervyn Bradford Medlycott. With his deputy, Lieutenant Flood, he managed to survey the river mouth, take a considerable number of soundings, flow directions, measure width of adjoining creeks and determine the location of various villages. Overall, in 12 days they covered a hundred miles, just navigating previously unknown creeks.5 The only positive result was that in 1877 a quite good chart was published by the British Admiralty of the mouth of the river (Fig. 15.1). To round this historic cartographic overview off, I want to mention the 1883 Capello E Ivene’s “Carta do Curso Do Rio Zaire”. This one has quite a bit of (Portuguese) place names but lacks a reasonable layout of the islands and shorelines, compared to the Tuckey map. However, the first map with an acceptable depiction of the region is the 1891 E. J. da Costa Oliveira “Carta do Curso Do Rio Zaire de Noqui ao Oceano” (Scale of 1:200,000). Nevertheless, it is a quite elementary depiction and cannot be called a chart as it has no nautical details. Charles de Rouvre (1881) in La Guinée méridionale indépendante: Congo, Kacongo, N’Goyo, Loango, 1870–1877. p. 299. Sailing up the [Congo] River, one can admire the gigantic and inextricable vegetation that lines the shores. Here and there, where a clearing is accessible, it is occupied by habitation. This aspect, with some variations, is maintained up to the approach to Ponta da Lenha, some thirty miles from the river mouth. By then we have passed the post of San Antonio, at

4 It is not clear what was meant by “Cape Pillar.” If this is the Monolith, then they would have sailed up to past Princes Island. 5 This was in essence a reconnaissance mission for a punitive raid days later by six British warships (among them HMS Spiteful) upon so-called “Black pirates’ nests.” In this murderous action many of the villages that had been located earlier were burned to the ground.

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Fig. 15.1 A colorized fragment of an 1896 plan, published by the CFS (probably in 1904) and partly based on the 1875 Medlycott-Flood-Vidal chart. The CFS authorities added the buoyage which allows us to partially reconstruct the thalweg. For clarity, soundings have been omitted. The map is obviously quite distorted. When lining up Boma and Malela, the actual Angolan shore (dotted black line) is represented together with arrows indicating the corresponding headlands. The northern shoreline is equally deformed and too far north the far end of Diegos Bay, in front of the Tchimma-Bika Creek and Quissanga on the left [or south] bank and on the right bank Malela. In that spot begins a section of vast islands, announced from the river mouth by a mirage. Covered by tall grasses and thick herbs, these islands are a perfect scenery for hippos. Here and there the patches of land include a bluff of palm trees. The soil is of the alluvial type, covered by a foot or two thick layers of humus. During flood stage this layer, otherwise held in place by the entanglement of the root system and fed by the low water level in the dry season, is uplifted and detached in one solid bloc, taking all the vegetation with it. They form floating islands, sometimes a kilometre [0.6 mi] long, that drift downstream and slowly break apart. They have been observed even twenty-five miles out at sea. While two walls of high vegetation have up to now prevented us from discovering the winding shore line during our journey upriver, we can now observe the first high ground and, just as well northward as southward, we can distinguish denuded mountain peaks, covered in a slight blue tint. We have left, on the north bank, Ponta da Lenha and the arroyos [creeks that are dry in the dry season] that lead to Katala and Loango and on the south bank the arroyos that lead to Chissiango and Congo-Hiale.6 After a few hours, the river widens again. We need to switch from one shore to the opposite one to avoid certain shoals and then we encounter in front of us a massive rock formation, cut up by precipices and vegetation: it is “Fetisch Rock”, revered by the

de Rouvre corrupted the names of Chichianga and Congo-Yella. The first was a settlement, halfway between Quiambe and Palm heads, on the plain of Congo-Yella, the then Portuguese possession on the south side of the river.

6

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indigenous people. They have never dared to venture onto the rock. At first sight, on approach, one thinks it is an isolated feature along the shore, but then one can see, in the distance, other peaks, as if they were sown across the plains, well broken by gullies, formed by heavy downpours. Seventy-four kilometres [46 mi] upstream from Ponta da Lenha, as the crow flies of course, since it is very difficult to take into account the many detours our vessel is obliged to make to avoid on the one hand the many high grounds and on the other the turbulent flows, lies the important N’Boma factory, practically established at water level on the right bank of the Congo.

The first modern hydrographic survey of the Maritime Congo River was conducted in the final year of the nineteenth century. HMS Rambler,7 a threemasted survey vessel of the Royal Navy, conducted extensive hydrographic surveys in various parts of the world. While she was en route from Fernando-Po Island8 to Loanda in Angola, she was ordered to conduct a general survey of the Congo estuary. As such, in September and October of 1899 she made a general bathymetric survey from Banana to Matadi and, on April 26, 1901, the first purposely made hydrographic chart of the maritime stretch of the Congo River was published in London. Rambler took water samples at various depths, measured density, salinity, temperature, flow, bed material, etc. One of the findings was that fresh water starts to encounter seawater downstream from Quissanga Island. The layer of fresh water then starts to thin until near Bulabemba Point where it is only a few feet thick. Water samples were analyzed in the UK and showed quite a bit of sand particles. The result was a chart, published by the Admiralty in 1901, later updated. This chart was later known by mariners and hydrographers as the “Rambler Chart.” One had to wait until 1916 for the first modern hydrographic chart, but only depicting the Boma Roads, produced by the Belgian colonial services. It was the work of Jules Nisot, whom we have met earlier, who between 1918 and 1920 charted the Fetish Rock Pool. He considered this expanse of water, between Birds Island and the Angolese coast, the key to improving the maritime access to the colony (Fig. 15.2). What everyone could see at the time was that the Congo River, unlike most large rivers in the world, does not create a delta when it reaches the ocean. Instead, and that was not entirely obvious then,9 it ends in a massive submarine canyon that starts inland, some 20 km [12.5 mi] upstream from Bulabemba Point. It quickly gains depth and by Banana has already reached between 300 and 400 m [1000–1300 ft]. The canyon has a length of 300 km [186 mi], first cutting through the continental

7

Commander Herbert Edward Purey-Cust (1857–1938), later Admiral, in charge of the survey. Fernando-Po, today named Bioko, part of Equatorial Guinea but laying in front of the Cameroon coast. 9 Early soundings for telegraph cable laying had indicated that there was a canyon, but the extend of it was unknown. 8

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Fig. 15.2 The mouth of the Congo River with the onset of the tortuous course of the Congo Canyon. The darker triangles represent 1930s first-order triangulation points. The other points are secondary survey benchmarks

shelf, then through the edge of the shelf to end in a wide fan—a terminal moraine— where the sediment, carried from the Haut-Congo, settles at a depth of between 3000 and 4000 m [10,000–13,000 ft]. Here the Congo Fan is 500 km [310 mi] from shore and has a similar width. The walls of the canyon reach a height of 1100 m [3600 ft] with a width10 of 15 km [9 mi].

15.1 Physical Description of the “Divagante” Region11 While the first 30 km [18.5 mi] of the Congo form a single corridor, past Malela the river splits in four arms. Here starts a 40 km [25 mi] long, braided section, an inland delta with a multitude of ever-changing islands (Fig. 15.3). These islands are made up of alluvial silt, deposited in striated lines because of thousands of years of flooding and retreating waters. The vegetation follows that pattern; drier and sandy elevations are sparsely treed, the intertwining, former gullies, since they are wetter, have a lush vegetation, composed of grasses and bush. When these arteries or veins are recently formed, they present pockets of potholes with the result that the vegetation is even more luxuriant. This multitude of half-dry channels criss-cross each other, creating a varied tropical landscape.

10

Hence, the Congo Canyon is smaller than the Grand Canyon, but, if we could drain the ocean, it would still be an impressive geological “land” formation. 11 In the French hydrographic literature, the region is called: “région divagante,” meaning “wandering” or braided section of the Maritime Congo River. I will use both terms throughout this book.

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Physical Description of the “Divagante” Region

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Fig. 15.3 The first relatively correct topographical map of the entire Bas-Congo appeared in 1901 under the auspices of Hubert Droogmans. Here is a redraw of an excerpt, depicting the braided section of the Maritime Congo

While the upstream side of an island is mostly green, the downstream side often ends up being a jumble of exposed beaches. If the beaches manage to persist for a few years, they get invaded by the same vegetation and might build their own beaches. But then, the flood season might wash large chunks of beach and island away and deposit the material further downstream or take it right out to sea. Except for the Grand Isle of Mateba12 and the island of Katala, none are inhabited permanently. In the days of the CFS Mateba Island was owned by an Antwerp businessman who used it for cattle grazing and palm oil production. Connection with the outside world was conducted through a small settlement at Sicia, on the west side of the island (Fig. 15.4). Looking at the Angolese mainland coast, the south side of the divagante region, from Lucala Island in the west to east of Fetish Rock, a large plain stretches out, composed of deciduous forest patches in the wetter depressions and wood savanna in the open stretches of land. It is called the Congo Yella Plain. Fetish Rock is a 35 m [115 ft] high, rocky remnant of the western edge of the Crystal Mountains. A small Angolese settlement, Emilio de Carvalho, sits in the wide plain, south of the rock. Other rocks, more dangerous for shipping, as they are submerged in the river, lay close to Fetish Rock, upstream in the Ntua Nkulu Pass, formerly called Belgian Pass: Mambuku, Kinkela, and Nzenze Rocks.13 From Fetish Rock downstream, the shoreline forms a circle segment, encompassing a first bay in The Grand Island of Mataba has a surface area of 11,340 ha or over five times the total area of JFK airport. 13 Before the 1980s known as Jorgenson, Triquet and Winton Rocks, respectively. 12

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Fig. 15.4 The key geographical features in the braided section, the second reach of the Maritime Congo. In essence four large islands are a constant, although their shape fluctuates: Mateba Grand Island on the Congolese side, Birds, Bulikoko, and Papyrus Island on the Angolese side. Their heads form “hard points” in the flow pattern of the river

which two, or sometimes three, islands continuously seem to move around: the Payu, formerly Penfold Islands. Hydrographically the bay forms the northern part of the Fetish Rock Pool. The circle segment ends at Payu (Penfold) Head where a second bay starts. The curvature of its shoreline is less pronounced and is formed by a 6–7 m [20–23 ft] high cliff line. Here too, one or two islands move around: the Ducks Island(s). It is the southern half of the Fetish Rock Pool. Some 2000 m [6560 ft] offshore, the river is dominated by the elongated Birds Island.14 The Angolese shore has another “hard point”: Palm Head. It is not really a hard point as it is a slightly curved shore and constantly reshaped. Shrubs and treelines delineated old river channels and various smaller islands offshore form real archipelagos: Papyrus Islands, Iguana and Hummingbirds islands, and the Nkakala (formerly Monro) Archipelago. On older maps the narrow channel along the shore is called “Rio de Sonho.” Habitation is almost nonexistent, except for a handful of buildings at Chichianga (Kikianga). This third river curvature along the Angolese coast ends at Quiambe Head (Nkonko Kiombo), in colonial times called Claeyssens Head.15 From Quiambe Head to Lucala Island the south shore continues in an elongated curve towards the west. This is along the last stretch of the braided river and is 12 km [7.5 mi] long. Narrow side channels first follow the shoreline, then cut deeper inland thereby widening the band of lush vegetation as we get closer to the ocean.

Birds Island (Macacos): About 1600 ha but, as it sits in the centre of the stream flow, the surface area varies predominantly in its downstream grounds. 15 Claeyssens, Joseph (1884–1966): Master Mariner and hydrographer. Served from 1911 to 1924 on the maritime section of the Congo River. Philanthropist. 14

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Physical Description of the “Divagante” Region

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Habitation is non-existent. Two Angolese islands separate the braided section of river from the last, straight run to the ocean: Lucala and Quissanga island.16 They might not look like it, but they are indeed islands with a combination of shrub and wood savanna, but only separated from the mainland by hundred meters [330 ft] wide, winding channels. A few tiny settlements along the narrow beach are cut out from the tropical forest: Senda and Quissanga Head, across from the Congolese shore of Malela. Further downstream is Jacarés (“alligator” in Portuguese) and Quissanga proper. In the olden days white sailors called this coastline Scotchman’s Head. The braided section disappears and from here the river is constricted to one, straight channel towards the Atlantic coast. North, across from Scotchsman’s Head, is the DRC shoreline. Here, at Malela, the river is almost 6000 m [4 mi] wide. Returning inland, several shoals and islands are continually shaped by the river flow. The shoreline is formed by Malela Island, indistinguishable from the mainland due to the many narrow mangrove channels that crisscross the hinterland. To the west lays the Nzadi (Creek) Zayenga, to the east the Pubo Creek. In front of Malela lay, from west to east: Zunga Kai Kambula Island and Kompanga Island. They are separated by the Rambler Pass. Further east is the Malela shallows with the Mangonda (Lawrence) Archipelago. Seagoing vessels must hug the Angolan shore as the river is deeper and more stable there. The headland of Pubo Creek was once known as Henderson Head, the northern counterpart of Scotchman’s Head. East of it, along the beach, stretches out a long row of fishing dwellings. They continue past the sinuous entrance to Zenze Creek, the western end of Katala Island. The island has the same dense tropical vegetation as further west. The old shore settlements of Ponta de Matala, Loanda, Longo, and Ponta da Lenha have disappeared. The village of Katala in the northeast, where the Zenze Creek rejoins the river, is the only shore settlement left in the area. The oval-shaped island of Tunga, at the entrance to the Luango (formerly Maxwell) Channel, is also densely covered with tropical forest vegetation. Between Tunga and the Grand Isle Mateba, where there used to be a second, wide channel giving access to the Luango Channel, today mudflats have filled in the channel. They have a sparse vegetation, consisting of isolated and clustered bush, surmounted by the odd tree. One day, the flats might disappear again. The Grand Isle Mateba has a varied vegetation, like a painting with hundreds of tints of green brush strokes. From old maps we know that in its long history it used to be an amalgamation of islands, changing configuration with each flood season. Hubert Droogmans described the island in 1901:17 In its western end the long and low island has a thick gallery forest, of which a certain number of trees are excellent as construction timber, and some wild coffee-

16

At 1675 ha, Quissanga Island is in area more stable than Birds Island as it lies outside the main streamflow. 17 Droogmans, Hubert (1858–1938): In 1894 Secretary-General of Finance for the CFS. From 1908 to 1911: Secretary-General of the Belgian Congo. Published in 1928 the first edition of the Atlas of Katanga.

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15 Early Maps of the Maritime River

trees. The soil is mostly boggy. The centre of the island has a large swampy plain, while the eastern end is composed of solid and dry ground, composed of fertile turf one metre [3.3 ft] thick, in certain places up to two or three metres [6.5 to 10 ft].18 The most southerly point of the island is called Ziamanganga (Convensaingh in colonial days). Since from here, one has a wide overview of the Mateba Downstream Pass, Ziamanganga has always been a reference point for hydrographic surveys. A few small settlements still exist on the island’s south shore, Mateba village and Tshiongo, across from the ever-remodeling Hippo and Turtles archipelagoes. On the north shore a village called Kudi Boma (Cul de Boma) is situated around two, 50 m [164 ft] high, hillocks with a smaller, third in between. Early in the twentieth century a bench mark—and a signal—on the western hillock formed the origins of a local topographical grid. These hills, along with the Monolith, Fetish Rock, Vambano, and a few minor ones, are the remnants of the Crystal Mountains, a geology that at this point is descending into the river estuary. The northeastern end of Mateba Island is heavily transected by narrow, open channels or elongated ponds as it gets the brunt of the floodwaters when they come down from the constricted river corridor between Matadi and Princes Island. At some point in its history, it was a separate island, named Ntua Nkulu. The name disappeared from maps in colonial times but has now resurfaced as there is a gauging station of the CVM. Around the turn of the nineteenth century several settlements dotted the Luango Channel shore and further inland, but only one still exists: Zambi. Seven to eight kilometers [4–5 mi] to the north, on the higher ground, the N1 motorway follows the curved channel. It connects Moanda at the Atlantic coast with Boma and, since the construction of the Underhill suspension bridge at Matadi, to Kinshasa. The people, once living in the multitude of small villages along the lowlands of the river, seem to have migrated to the N1 motorway where making a living is easier than decades ago, closer to the river. Northeast of Zambi the Lukunga River enters the Luango Channel. This river comes from the north and drains the Vungu wetlands.

15.2

From Boma to Matadi

In front of Boma lie three large islands, sometimes accompanied by one or two smaller ones. They are Angolese territory and, from west to east, are named Selonga, Sacra Ambaka, and Rocca islands (Fig. 15.5). From Princes Island—just east of Boma—to Matadi, 56 km [35 mi], both banks of the river are made up of an uninterrupted line of hillocks, some reaching or even surpassing a height of 250 m [820 ft]. Their summits have been rounded through

18

Quoted from Mouvement Géographique, 1885.

15.2

From Boma to Matadi

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Fig. 15.5 The third reach of the Maritime Congo River, from Princes Island to Matadi. The navigable channel follows several connecting, straight lines indicated on shore by several back and front beacons. Important topographic bench marks (and their respective elevations) are again represented by colored triangles and roundels

erosion and the vegetation is meager, mostly concentrated in the many valleys winding their way to the river (Fig. 15.6). While at Boma the river is still 4000 m [2.5 mi] wide, 5 km [3.1 mi] upstream, at Princes Island the river width only measures 1250 m [4100 ft]. Here starts the corridor toward Matadi, the final stop for ocean-going vessels. The river, now only a 1000 m [3280 ft] wide with short and sometimes sharp bends, strewn with islets and rocky outcrops, follows a restricted, deep, and turbulent corridor lined with hills.19 This reach produces a variety of small and large whirlpools that complicate navigation for seagoing vessels. Navigating this stretch of the river can be toilsome, sometimes even dangerous during flood stage. At the low-water stage, the minimum depth is 10 m [33 ft], but in a lot of places depths between 20 and 30 m [65–100 ft] have been sounded, sometimes even between 40 and 50. Just downstream from Matadi, lies the most notorious whirlpool on the river: “Hell’s Cauldron” (Chaudron de l’enfer). It is an amphitheatre-like corrie,20 2000 m [6560 ft] in diameter, where the mighty Congo makes a 90-degree angle and the waterflow can reach 16 km/h [8.6 kts] or even more. Depths in the cauldron have been measured to be 100 m [330 ft] and more. Well into the twentieth-century seagoing vessels often needed full power to navigate through this turbulent section, keeping to the outside bend to avoid the large whirlpools and eddies in the center. One small mistake by the helmsman could render the ship rudderless, suddenly

19 20

This broken terrain is not very hospitable to the development of towns and industries. Corrie: From the Scottish Gaelic coire. In French Cirque.

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15 Early Maps of the Maritime River

Fig. 15.6 A Borassus tree, pictured in 1923. (Devroey Family Archive)

pushing it downstream and into the lush vegetation (Matitis) of the shoreline. Once passed Hell’s Cauldron the flow stabilizes to 5 or 6 km/h [2.7–3.3 kts] at low water, 9–10 km/h [5–5.4 kts] in the wet season. Nevertheless, except for an unusual high runoff—as in 1924—ships running at eight knots (14.5 km/h) minimum can ascend the river to Matadi year-round (Figs. 15.7 and 15.8).

15.2

From Boma to Matadi

113

Fig. 15.7 An aerial, downstream view, of the port of Matadi in 1934. A. The Matadi Wharf; B. The Fuka-Fuka Wharf; C. Underhill Point; D. Noqui (ANG); E. The railway Matadi to Kinshasa, slowly climbing along the steep hill towards the M’poso River valley. (Devroey Family Archive)

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15 Early Maps of the Maritime River

Fig. 15.8 A more recent view of Matadi, this time upstream. In the foreground the Kala Kala Wharf with large warehouses. (Photo Ir. S. Ides)

Chapter 16

The Acute Need for Bathymetric Surveys

Abstract It was quickly recognized that for successful shipping, bathymetric surveys would be essential and in 1887 the first soundings were completed between Boma and Matadi. But the main problem lay in the braided section. Here it was a matter of maintaining and even improving the meandering thalwegs. So, after 1901, when the first topographical maps of the Bas-Congo became available, hydrographers had a basis to start soundings in this reach. Colonel-engineer Pierre Van Deuren, who had studied the hydrography of the Lower Congo in detail, suggested a few solutions to the problem but in fact, the first bathymetric measurements extended from the first land surveys in the vicinity of the CFS capital of Boma. Keywords Peters J-J · Winton Rock · Captain Boye · Mahieu A · Van Deuren P

16.1

The First Soundings

With the establishment of the CFS in 1885, it became apparent that the detailed sounding of the river had to be a priority. It is noteworthy to indicate that on July 20, 1885, only days after the Congo Free State had been declared, the steamer Ville d’Anvers, with some 60 European public servants on board, hit a submerged rock near Fetish Rock on its voyage to Boma and Vivi. The ship sank, but thanks to the local Musorongo people rushing to the rescue, all souls on board were saved. The accident occurred on the later so-called Winton Rock, just upstream from Fetish Rock. At the time, the obstacle only gave a 4.40 m [14.4 ft] clearance. Due to this fact, a year later the Danish captain Boye1 was contracted by the independent state and upon arrival in the Congo was put in command of the state’s vessel Héron.2

1

Boye, Hans-Albert (1848–1932). Master Mariner. Became Head-Pilot on the maritime section of the Congo River in 1886. Three years later he piloted the first ever ocean-going steamer to Matadi. 2 The Héron was a former tugboat (115 tons) that had been employed on the North Sea. At the beginning of 1882, the vessel had left the Port of Antwerp and, with six passengers on board, later reached the Congo. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_16

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Fig. 16.1 View from the north toward the eastern outskirts of Boma in 1929 with in the background the Angolese island of Sacra Ambaka and its 74 m [243 ft] high, upstream hill. (Devroey Family Archive)

In that capacity, the next year, he buoyed the entrance to the Banana Creek and the Congo River in the vicinity of the Angolese island of Quissanga, across from Malela. His initial sounding work indicated that in the three potential choke points— Quissanga, the Mateba shoals, and the Fetish Rock Pool—he could always guarantee a depth of 7.30 m [24 ft]. In his capacity as Head Pilot, at the start of 1888, he personally took several large ocean-going vessels, with a draught of 6.40 m, safely through the braided section of the river (Fig. 16.1). In 1887 then, Boye accomplished the first bathymetric survey of the Congo River between Boma and Matadi. Up until then Matadi had been a desolated hill, as initially a post had been established at Vivi, a short distance upstream, on the opposite side of the river. But Vivi was not deemed a suitable anchorage for large vessels as it was too close to the first cataracts and on the wrong side of the river. Indeed, by now the border between the French and the Belgian Congo had been agreed on and France would possess part of the north bank of the river, starting from Manianga. Stanley had argued that, to conquer the cataracts, a railway should be built from Vivi to Isangila, then barges could take goods and passengers to Manianga where the same could transfer to the south shore and continue their journey by rail again up to Kinshasa/Léopoldville. Railway experts nevertheless disagreed. The so-called navigable stretch between Isangila and Manianga was after all not that easy to navigate and transferring goods and people twice between Vivi and Kinshasa would be too cumbersome and not economical (Fig. 16.2).

16.1

The First Soundings

117

Fig. 16.2 A sounding boat on the river in 1932. The davit in front of the mast, under the high canopy, could haul in or set out buoys over the side. Notice the bicycle by the stern. (Devroey Family Archive)

It was agreed that the only possibility would lay in the construction of a railway, entirely on the south side of the river, straight from Matadi to Kinshasa.3 Boye’s survey revealed that ocean-going vessels would have a minimum of 18 m [59 ft] depth, all the way from Boma to Matadi. Soundings by engineers of the railway company at the Matadi anchorage furthermore indicated that steamers with a draught of seven meters [23 ft] would be able to moor at a 50-m-long pier [165 ft] projecting from the shore into the river. On June 20, 1889, Chief-pilot Boye, with captain Murray at the helm of the Lualaba, steamed up to Matadi. At the time, the trip from Boma to Matadi, by steamer, was 6 hours up, and 3 hours down. Nevertheless, experts later would declare that the Free State administration had not spent enough effort on improving the navigability of the river. It was with the take-over by the Belgian government that the hydrographic service got the attention it needed. Only then the first reliable charts of the river were drafted, and buoyage and dredging tasks became a priority. Still, when the brand-new steamer Elisabethville4 traveled upriver in 1911, having a draught of only 5.9 m [19.3 ft], and following a fairway indicated as being 6.5 m [21.3 ft] deep, it hit bottom in two spots where it was known that the navigable pass was narrow.

It would still take 11 years for the railway to be finished. The Elisabethville, first “Congo Boat” with that name, served the CBMC from 1911 to 1917, when it was torpedoed on the 6th of September. It had a deadweight of 5695 long tons. 3 4

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While Boye was investigating the riverside of things, Captain Jungers had been leading a topographical team establishing the cadastral boundaries of all properties of the CFS between Banana and Vivi. One of the results being that the delineation of the river shoreline in many places significantly improved. All this work resulted in 1896 in the publication by the Marine Service of the CFS of a map of the maritime section of the river.5 In 1901, Hubert Droogmans published the first edition of 15 topographical sheets of the Lower Congo Region at a scale of 1:100,000, from the Atlantic Coast to the Malebo Pool (then called Stanley Pool).6 With it he added an explanatory annex, for every sheet a description of the hydrography, the soil conditions, main populated places, geographical coordinates, including trail distances, measured by mechanical pedometer. The entire publication was in French. As for the island contours in the braided section of the river, Droogmans used the cartographic survey of HMS Rambler but for the area of the Boma Roads,7 he based his map on the 1895 triangulation of Adolphe Mahieu.8 Mahieu’s topographic work, the first dedicated on a section of the Maritime Congo River, suggests that the aim was to conduct the first hydrographic survey of the anchorage as Boma was the capital of the CFS. Since Mahieu had been dispatched to the Congo to build the Shinkakasa Fort, he most likely established a baseline between a bench mark on the Boma shoreline and the fort. Measuring the angles of this line with a signal on Sacra Ambaka Island, he could then start his triangulation. With the exact local coordinates known, these points could then be used to start a bathymetric survey of the anchorage (Fig. 16.3). In the olden days, the basis for any large-scale topographic survey consisted of the set-up of several bench marks in the area to be surveyed. This procedure rested on the principle in trigonometry that, if one knows the length of one side of a triangle, the two other sides can be calculated after measuring the contiguous angles of that side to a third point. Once you know the length of the other two sides, you can use that information to measure and calculate the next triangle. Eventually you can establish a grid pattern over large distances, simply by measuring angles. To increase accuracy and minimize errors in the system, the entire operation is mathematically more complex than explained above and will usually involve the incorporation of a second measured baseline at the far end of the grid. Physically measuring a long distance accurately involved many repeated measurements, considering temperature variations, chain or ribbon strength, metal expansibility, and others (Fig. 16.4). 5

This was the 1896 CFS Plan, a compilation of earlier maps by Royal Navy officers Medlycott, Flood & Vidal with additions by the CFS, mentioned earlier. 6 The kilometre grid projection on the maps is based on an origin in x at 20° E and the y at the Equator. This results in x increasing from east to west, and y increasing from north to south. 7 Depths in the Boma Roads are well over 20 m [65 ft]. 8 Mahieu, Adolphe (1853–1929). Engineer-officer & civil servant. Leaves Belgium for Congo in 1894. In 1895 he surveys the Boma Roads. Participated in the construction of the Shinkakasa Fort, west of Boma. He had been asked to verify the map of the river between Fetish Rock and Princes Island. Eventually he would spend five stints in the Congo.

16.1

The First Soundings

119

Fig. 16.3 An extract of the Droogmans Map showing Mahieu’s triangulation points. Hydrographer Jules Nisot would carry out the bathymetric survey in 1916, based on Mahieu’s land survey work

Since it had been recognized before the end of the nineteenth century that the region of eastern Congo—along the 1200 km [746 mi] border of the Great Rift Valley—was rich in natural resources, from 1900 on cartographic missions had been conducted along the African Great Lakes by Belgian, German, Portuguese, and British surveyors9 in mixed teams. The first field experience gained during those early topographical expeditions would be valuable in the later surveys in other parts of the country. While the “Droogmans Maps” were more of a descriptive nature of the landscape, it was the first serious geographical attempt to describe the Lower-Congo region. As for the maritime stretch of the river, only two navigational details—two “Clusters of 9

These happened between 1897 and 1924 and involved over 8000 km [4970 mi] of state borders, following thalwegs in rivers and lakes (4800 km, 2983 mi), crest lines of mountains (1800 km, 1120 mi), convention lines like meridians and parallels (800 km, 500 mi) and a mix of the above (700 km, 435 mi). This monumental task was based on large swaths of triangulation chains in mostly inhospitable terrain and under extreme climatological conditions.

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Fig. 16.4 A Belgian hydrographer is examining a bathymetric reading while a Black sailor looks on. Notice the set of wires and pulleys emanating from the davit and the lead line. This picture was taken on the stern of the sounding boat, pictured earlier. The bronze plaque on the wall says that the vessel was built at the “Chantier Naval Hoboken” in Belgium. (Devroey Family Archive)

shrubs & trees”—were incorporated, so in that sense it was not much of a navigation chart, but it gives an indication of the way the river was navigated by the European mariners in those early days of the CFS. Between 1914 and 1918, due to the First World War, most of the survey and cartographic work on the maritime river ceased. In 1920, the Geographical Section of the Naval Intelligence Division, Royal Navy, wrote: About 20 miles [37 km] upstream [from Banana] and opposite the Portuguese port of Kisanga [Quissanga] on the left bank, the river divides into two channels. The old passage along the north bank known as the Mateva [sic] Pass route has not been used for a number of years on account of the insufficiency of water [meaning shallow waters]. That along the southern bank, formerly called the Congo-Yella route but now known as the Fetish Rock or Portuguese route, is taken by practically all vessels going to Boma. The depths on this route vary from 10 to 4 fathoms [18.2 to 7.3 m], except in the parts south-east of Birds Island and south of Fetish Rock, where a depth of 20 feet [6.10 m] is maintained by dredging.

16.2

Pierre Van Deuren

121

While the distance—as the crow flies—between Malela and Boma is 51.5 km [32 mi], depending on the fairway in use, the distance traveled by ocean-going vessels can get up to 61 km [38 mi], or almost 20% more.

16.2

Pierre Van Deuren

Like many other Congo experts in Belgium, realizing that the economic future of the Congo depended on a reliable maritime access to the colony, World War One veteran Col. Pierre Van Deuren10 in 1925 started working on a proposal for a deep-water port on the Maritime Congo River, connected to the Haut-Congo via a navigable inland waterway through the cataract region. He envisioned the construction of a series of dams, and locks, coupled to hydropower stations to move barges directly from this new port to Kinshasa. Initially he was developing his concept behind his desk in Brussels, but in June of 1927 he embarked on the steamer Elisabethville11 for the Congo to verify his ideas with the reality of the lay of the land. Before his departure, as he would need the latest topographical information on the region, he consulted with the Military Cartographic Division regarding the ongoing Cartographic Mission of the Ministry of the Colonies. Upon arrival in Boma the local commander provided him with the latest maps on the cataract region and on his long trip along the banks of the river he got the company of three topographical officers. During a conference in Boma with Colonel Weber12 and under the direction of Mr. Maury,13 Van Deuren proposed to extend the present cartographic work from Matadi downstream towards Banana to attach the existing survey work to the zero in Banana. As such the entire lower Congo region would be covered by a unified network with contour lines, at least at 50 m [164 ft] intervals (Fig. 16.5). Van Deuren recalled: From our arrival in Congo, our attention was attracted to the important difficulties, posed by navigating the passes of the river downstream from Boma. The situation was particularly difficult as the month of July coincides with the low water season, which happened to be

10

Van Deuren, Pierre (1878–1956): Engineer-Professor at the Royal Military Academy in Brussels. Developed a trench mortar during the First World War, adopted by the allied armies. Retired from active service in 1923 to devote his time on various scientific projects. 11 Elisabethville (2): CBMC Passenger liner. In service between 1922 and 1947. 7180 tons deadweight. 12 Weber, Charles M J (1875–1952): Artillery officer. Before the First World War involved with determining the eastern and southern borders of the Belgian Congo, together with Maury. 13 Maury, Jean G F H (1880–1953): Chief-engineer, Director of the Cartographic and Geodetic Service of the Colonies. 1904–1910: First Congo tour as Engineer officer but resigns from the army. Graduates as an electrical engineer. Visits the Congo multiple times as a civil servant (between 1911 and 1946). Professor of astronomy, geodesy, and topography at the Royal Military Academy in Brussels.

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The Acute Need for Bathymetric Surveys

quite low in the summer of 1927. Upon our arrival, at the end of June, we encountered a German steamer, stranded in a pass, which could not be freed without the assistance of the tugboat President Francqui.14 Our own vessel, the Elisabethville, could only pass after unloading 500 tons into local barges and then, the boat still ran aground and could only free itself after many hours. As a result, we arrived in Boma and later Matadi with a day's delay. A month later, in July, the Thysville15 had similar problems. She eventually could pass with a draught of twenty feet [6.10 m]. Coming down from Matadi, the boat had only nineteen feet of draught [5.80 m] but all her potable water reservoirs were empty. On several occasions the vessel scraped her keel on the bottom and then later lost many hours refilling her water tanks. At the same time, the French steamer Asie, at 21 feet [6.40 m] got stuck in a pass and lost three days working herself afloat again. In the first two weeks of August, two Portuguese steamers of 6 to 7,000 tons, chartered by the CBMC, were anchored downstream from the passes, unable to make it through. One of them was immobilized for seventeen days. In turn the Stanleyville16 got stuck. Barges took on 1,200 tons of its cargo, a task that took three days to accomplish.

As for the solutions he proposed to remedy the complex morphology of the river: Navigation through the braided section of the river currently involves important dredging operations. Vessel passage occurs at present along the Angolese coast, the Monro Islands, Nisot Pass and Fetish Rock. This fairway needs to be kept open at any price, even if only precarious, if we want the port of Matadi to remain open to seagoing vessels. Dredging therefore needs to continue, uninterrupted.17 Downstream from Boma the river splits in three distinct courses or arms, each one meandering between islands and sandbanks that continually move. The difficulties of navigating this section consist of finding a way around the sediment arriving from upstream and settling in the Pool because of the slowing down of the water flow due to the widening of the river and the growing influence of seawater vs. fresh water. In order to determine the fairway, we have to take recourse to all the means that are used with success elsewhere: apart from the dredging, we have to mention adjusting the waterflow by means of groynes, speeding up the water flow by narrowing of certain sections by means of levees, even by possibly erecting a dam to block a certain waterway of the river.

Professor Van Deuren believed that the minimum depth of the fairway should be at least 9.15 m [30 ft]. In addition, he mentioned: “It is also interesting to note here that it would be advantageous for the colony to establish a fairway along the northern route, along the so-called Monolith [the Luango Channel, then called Maxwell Channel], waterway of which both shores are in Belgian territory, or at least along the central pass, along the Mateba island where at least one shoreline is Belgian.”18

14

President Franqui: CBMC tugboat in service on the Congo River between 1921 and 1927. 278-ton deadweight. 15 Thysville (1): CBMC Passenger liner. In service between 1922 and 1948. Sister ship to the Elisabethville (2). 16 Stanleyville (2): CBMC Passenger liner. In service between 1926 and 1932. 7518 tons deadweight. 17 Van Deuren was thinking of a new, deeper, and more easily accessible seaport. Eventually he would propose to develop Katala Island as a new port. 18 Since its independence from The Netherlands in 1830, Belgium has had a complicated history of sharing the authority over the Scheldt River, sole access to the Port of Antwerp but through Dutch territory.

16.2

Pierre Van Deuren

123

Fig. 16.5 Aerial view from the north of Boma in 1934. A. Angolan mainland; B. Rocca & C. Sacra Ambaka islands. D. Boma city; E. Kalamu River; F. Today, Maluku Avenue; G. Highway N1 to Matadi. Today, the entire area is practically build-up. (Devroey Family Archive)

The first topographic surveys on the river, after Mahieu’s work on the Boma Roads, were not based on a general plan, but an extension on previous work, done by Jules Nisot from Fetish Rock westward. At the time the local topographic network had its origin (x = 0.00 and y = 0.00) on the Angolan coastline, south of Ducks Island on the mouth of a creek, on the 1928 map called “Geo Creek”.19 Once the

19 At 5°59″ S – 12°55′E, 1200 m [3940 ft] west of the western point (Base O) of the Portuguese Baseline on the Congo Yella Plain.

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topographic work extended further west from that point, the bench marks and calculations entered in “negative territory,” a complication and potential source for errors. So, in 1930, from Fetish Rock to Banana on the Atlantic Coast, a set of permanent metal pyramids were erected in anticipation of a new land survey from new triangulation points.

Chapter 17

Hydrographic Basics in the Tropics

Abstract To understand the initial challenges of the hydrography of the Maritime Congo River, we first look at the basics of depth measuring in the tropics. Around 1900 large ocean-going vessels would unload part of their cargo into barges to reduce their draught before crossing the shallow depths. As this procedure was time-consuming for the passengers and uneconomical for the shipping companies, the CFS administration soon acquired two dredgers that would deepen the troublesome passes. It was recognized that a different approach was needed in solving the navigability on the braided section of the river. Since only one or two hydrographers were stationed at Boma, their duties extended far beyond simple depth sounding. They ranged from meteorology to cartography and included buoy laying and land surveying. Keywords Salmoiraghi · Bathymetric · Sextant · Belgian Pass · Bucket dredger · Hydrography Since the magnetic compass came into use in the twelfth century, mariners had a chance to leave the coastal waters and sail away from land, thus allowing them to shorten their journeys to faraway ports. That in turn brought the need for sea charts that would depict dangerous areas, like submerged rocks and other shallow regions they might encounter. But how to plot these obstacles for safe navigation? While the first chart depicting soundings was probably made by the Castilian navigator Juan de la Cosa in 1504, it was waiting for Gemma Frisius, Dutch mathematician, to develop the theory of trigonometrical surveying a few decades later and the Fleming Gerhard Mercator, who solved the problem of projecting a spherical surface on a flat sheet of paper. These inventions would allow surveyors, with an acceptable degree of accuracy, to pinpoint objects away from land (Fig. 17.1). Hydrography1 is, among others, a combination of land surveying and measuring the depth of a body of water. To fix the location of a certain depth on a chart requires the point of measurement to be plotted on a map. By measuring the depth at multiple 1 The term “Hydrography” and “Hydrographer” were coined later in the same century but became only household names with the Royal Navy exploring bays and estuaries in its efforts to secure safe passage for its merchant’s ships throughout the British Empire.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_17

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Fig. 17.1 A surveyor on the Maritime Congo River with a large model Salmoiraghi tacheometer, in 1933. Behind him a steam-powered sternwheeler, used as a sounding vessel. (Devroey Family Archive)

points over an area one can, by interpolation, draw contour depth lines of the body of water. Before the advent of gps, the entire procedure started with a triangulation of the land around the body of water, as such installing several bench marks with known coordinates. From there the hydrographer could then establish secondary points along the shoreline, to be used as reference points during the actual sounding operation. These “signals” consisted of conspicuous natural or fabricated objects. In those days, in Europe, we would readily think of church spires, bell towers, wind mills, or other high structures. In Africa nevertheless, where in the beginning of the twentieth century tall structures were lacking, trees or bushes that stood out from their surroundings were usually selected as reference points. If nothing of the kind could be found, a simple long pole, planted near the shoreline would often do. This operation was conducted during a quick reconnaissance, most often by (steam or later motor) boat of the area. The coordinates of the land signals were determined through a classic overland survey by means of a triangulation or a traverse with a theodolite or even a sextant.

17

Hydrographic Basics in the Tropics

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Fig. 17.2 A modern-day version of a depth-sounding cable, still used to calibrate electronic bathymetric equipment on the Congo River. (Photo Ir. S. Ides)

Once enough reference points had been established on land, adjacent to the body of water, the hydrographer could start depth sounding. For that purpose, he traveled with a small sounding boat up and down the river measuring depths with a graduated measuring cable while at the same time determining his location vis-à-vis two or more reference points on shore. This required a sounding party, composed of the hydrographer and an assistant-hydrographer (the “observers”), a leadsman and a recorder, plus boat crew (Fig. 17.2). A few diverse methods were used to arrive at a bed profile in the braided section, depending on the circumstances and the available equipment. The most accurate way was to have two instrument persons, staffing two adjacent bench marks on shore and triangulate the boats position when the sounding was exactly taken. Each time a sounding was made, a flagger onboard signaled the action to the onshore crew by raising two flags, a white and a red one. Every fifth sounding only the red flag would be raised. This was a cumbersome arrangement as it was slow and required three isolated technicians taking independent readings and three notebooks to collate the data afterward. Another method was concentrating all actions on the sounding vessel. An operator would measure the angle by sextant to three known signals on shore while the leadperson would lower the lead. Still another method was to have two signals, one on the shoreline (the “front range”), the other more inland (the “back range”). Both would form an imaginary line, extending over the water. The sounding vessel could then travel the line and by means of the sextant only one other signal needed to be observed to get a direction

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Fig. 17.3 A sextant in its carrying case, displayed at the MRAC. Used horizontally these instruments were very practical in the Congo estuary to determine the angle between three known points on land. It thus allowed the hydrographer to calculate the position of each sounding

from. By setting up a series of poles along the beach one would create a baseline with distances between poles measured, one could create fan-like lines,2 a method that would save time while sounding. On a river with multiple channels, most of the time a combination of methods would be used. The introduction of walkie-talkies of course simplified coordination between the various members of the sounding crew (Fig. 17.3). Between Boma and Matadi, where depths of 50 m [165 ft] or more were encountered with flow speeds of 5–6 km per hour [2.7–3.3 kts], the procedure was different. A 7-kg [15.4 pds] weight, suspended from a Warluzel (piano) wire rolled on a drum was thrown overboard and the motorboat was left to drift with the flow. The experienced leadsman would keep track of the revolutions of the handle while the weight hovered close to the riverbed. When the drifting boat crossed the survey line, the man would call out the number of revolutions of the handle, thus the length of the wire, thus the depth at that point. Since straight cross sections of the riverbed had to be determined the survey sloop would then return across the survey line— travel a saw tooth course—and come round oblique for the next measurement. A complex and time-consuming operation where perfect coordination of the crew was essential. Surveying the shallow edges of sandbanks and along the shoreline where mooring was deemed possible was accomplished by a hand lead on a short wire. 2

See the 1942 divagante chart for an example, used in the Camoëns Pool.

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The Role of the Hydrographic Team

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By the end of the nineteenth century and up to 1923, European vessels bound for Boma had two options for sailing through the braided section: either the so-called “Belgian Pass”, south of the Mateba Grand Island or the “Portuguese Pass”, hugging the Angolan shoreline, through the Camoëns Pool and back to the Angolan side. The “Southern Pass,” although longer, was deemed quite stable, but a sand bar existed south of Fetish Rock where only a depth of 4.3 m [14 ft] was available. Owing to this obstacle, large vessels would unload part of their cargo at this point into two CFS-owned barges, but such a procedure was time-consuming and costly for the shipping companies. For that reason, the administration had bought a bucket dredger3 in Antwerp, but it was quickly recognized that this type of dredger was unsuited for work in the Congo. Vessels with a smaller draught meanwhile kept using the shorter Belgian or Northern Pass. Finally, due to the arrival of the trailing suction hopper dredger Mateba4 in 1904 the shoal south of Fetish Rock could be deepened so large vessels could reach Boma and Matadi (Fig. 17.4). While in 1901 a minimum depth of 4.90 m [16 ft] was guaranteed, by 1908 this had improved to 6.10 m [20 ft]. However, one dredger was deemed insufficient and a second unit5 was bought in 1910, slightly larger than Mateba. With both dredgers in operation, between 1911 and 1923 the minimum guaranteed depth in the fairway vacillated between 5.80 [19 ft] and 6.80 m [22.3 ft]. Yet, the situation between the Angolan coastline and the Penfold islands remained a concern. The passage was narrow, curvy and the shoreline eroded quickly, continuously depositing sand in the channel (Figs. 17.5 and 17.6).

17.1

The Role of the Hydrographic Team

In colonial times, the work of the hydrographer on the Congo River was quite diverse. This resulted from the fact that not only were the budgets always tight, but a large turnover in personnel and the lack of enough people on the roster at any given time made that the technicians had to be inventive and willing to take on tasks that were not strictly within their domain. The benefit was that the technicians of the Waterways Dept. learned a lot of additional skills in record time.

3

Cockerill: Later briefly used for land reclamation in Banana, but after that transformed into a coal storage vessel and the buckets used as anchors for buoys. At the time bucket dredgers were extensively used on the Scheldt River. 4 Mateba: Built for the CFS in 1903 in Haarlem (Conrad Wharf), Netherlands. 42.4 m long 7.7 m wide. Hopper volume 300 m3. Used until 1940. 5 Boma: Built at L. Smit & Zn, Kinderdijk, Netherlands. 56 m long, 9.5 m wide and a hopper volume of 500 m3. According to Wauters A-J, this was a cutter suction dredger. As dredging on the open river had to be suspended during the high flow season, the vessels were employed for land reclamation at the ports of Banana, Boma, and Matadi.

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Fig. 17.4 The bucket dredger Cockerill (in the background) in 1898 at Boma. Picture taken from the steamer Albertville, bringing European guests for the inauguration of the Matadi-Leopoldville railway. (Thys Family Archive)

Fig. 17.5 The “Belgian and “Portuguese” navigation channels through the braided section, until the beginning of the twentieth century. It was an updated “Rambler Chart” with the addition of a 4-km [2.486 mi] coordinate grid—here reduced to a 10-km [6.215 mi] grid—with the origin at Cul de Boma. As can be seen, the small, muddy channels criss-crossing the various islands were not yet surveyed at the time

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The Role of the Hydrographic Team

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Fig. 17.6 An unidentified cutter suction dredger on the Maritime Congo in the 1920s. Most likely this is the dredger Boma, acquired by the Ministry of the Colonies in 1911. Once lowered to the riverbed, the cutter head would spin and loosen the bed material. The sediment-and-sludge mixture would then be sucked through the large diameter pipe underneath the shaft to be disposed of in a barge. (Devroey Family Archive)

The basic duty of the hydrographer was to conduct hydrographic surveys and collect flow data with the aim to improve navigation and facilitate the study of the potential evolution of the fairway route. The hydrographer based in Boma and responsible for the entire maritime stretch of the river was at once a land surveyor, a hydrologist, a cartographer, an oceanographer, a supervisor of record keeping, and much more. Some of his duties could be classified as: 1. Maritime topography and bathymetric survey to draft charts on a regular basis so the evolution of the river could be followed by comparing successive charts. 2. Twice daily recording the water level, at ebb and flow—between Banana and Boma—and at flood stage in the wet season. 3. Supervision of the maintenance and installation of shore beacons and buoyage. 4. Study the stream hydraulics: flow, discharge, speed, slope, and wet cross sections. 5. Hydrology: determine water properties and the aquatic transportation of solids. Study the interconnecting channels that influenced the fairway.

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Fig. 17.7 The Mateba dredger on the Lower Congo in 1932. The boom or suction pipe can be seen, hanging over the side, halfway in the water. In the tropics the foredeck would have a tarpaulin to protect the sailors from prolonged exposure to the sun. (Devroey Family Archive)

Secondary jobs were related to meteorology, geology, morphology, and oceanography. Although this was a broad range of activities that the hydrographer had to deal with, it was essential to avoid the creation of a separate service which would have been expensive and slow to get up and running. One had to do with the means one had at its disposal. The instability of funding allocation and the high staff turnover were two factors that the waterways department always had to take into consideration with regard to the complex role the hydrographer on the Congo River had to play (Fig. 17.7). In the inter-war years, a Hydrographic Survey Team, composed of a hydrographer, an officer-cadet of the merchant navy, and a dozen Indigenous workers, conducted bathymetric measurements in the braided section of the river on an ongoing basis. They lived onsite on a housing barge, anchored close to the area of their work. Besides the normal survey and hydrographic equipment, their means of transport were a fast motorboat, a motor launch, and a small, motorized scull. Up to 1930 the hydrographers had a 250 by 150 m [820 by 490 ft] compound on Mateba Island—see “SHS” on Fig. 18.8—but apparently that arrangement proved too cumbersome for the daily commute to the river’s various river channels. The team not only gauged the contours of the riverbed, but also measured flow directions and speeds. These data allowed the Waterways Service to move buoys along the fairway according to the results of the fathoming of the Survey Team. Buoyage was the responsibility of the Officer-Buoykeeper employing a motorboat (vedette) based in Boma and he would daily measure the depth along the fairway in the braided section to direct the three service dredgers (TSHD of 500 m3) to the bars to deepen and, equally important, where to dump the dredged material.

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The Role of the Hydrographic Team

133

Alignments on shore and the location of the numbered buoys provided a reasonable precision to conduct these operations. The daily soundings made by the OfficerBuoykeeper also allowed him to decide if it would be necessary to widen or, on the contrary, even restrict the fairway in certain locations. Those decisions were normally only decided after the survey team would have been called in to make a more thorough examination of the area involved. Three times a week a motorboat would visit the surveyors and the dredgers with everyday provisions and stores. Coal for the dredgers was delivered separately by barges carrying 200 or 400 m3 of coal. A well-equipped machine shop together with a slipway and a floating drydock at Boma were part of the Waterways Department on the Maritime Congo. In ideal circumstances, two or three surveys a year were made of the winding fairway between Malela and Boma, the braided section of the river. Every 2 or 3 years a bathymetric survey would be conducted of the anchorages and the mouth of the river—from Bulabemba to Malela—and in the braided section, the areas outside the fairway. As necessary, the port approaches, the passes, and potential hazardous riffles got an additional survey. A dedicated workforce, supported by the above facilities, allowed the Service to bring the minimum depth in the fairway from 5.80 m [19 ft] in 1927 to 8 m [26 ft] 10 years later (Fig. 17.8).

Fig. 17.8 A black buoy on the river in 1934. At the time there were two kinds of buoys, depending on the side of the fairway they were anchored. They were all a similar spheroconical shape (In plain words, a pointed ice-cream cone, filled with a scoop of ice cream). The red-painted ones bordered the starboard (right) side of the channel going upstream, with the cone bobbing above the waterline. The black ones—like the one pictured—on the port (left) side, showed their spherical side up. (Devroey Family Archive)

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The Topographical Methods

The most important activity of the hydrographer was to conduct the hydrographic survey, also called “Maritime Topography.” A nautical chart, indicating the various depths in the fairway, resolves the immediate issue: providing security along the existing navigable channel. By comparing the chart in use with previous versions, the hydrographer can forecast, with some degree of certainty, the evolution of the riverbed in the short term. But a bathymetric survey could not proceed without the exact shoreline of the river being known and bench marks being established along it. These markers would function as reference points for the hydrographer to which he/she could tie the subaquatic measurements. Any large survey depended on four main elements: 1. Various methods to determine the primary and secondary reference points, as laid out earlier. In general, the main methods were the triangulation, the interpolation, and the polygons or traverses. 2. The instruments used determined the accuracy of horizontal and vertical angles (goniometer, later theodolite, or tacheometer) and the distances measured, direct (invar tape) or indirect (plane-table or stadia rod). 3. Careful control of all measurements and calculations and evaluation of the precision. 4. Use of the appropriate projection and scale in drafting the charts. The topographical methods used on the maritime section of the Congo River depended on the changing geography. From Banana to Malela the shoreline is inundated at high tide. Since the river is quite wide—between Banana and Padrâo Point (Angola) 10 km [6.2 mi], between Bulabemba Point and Fuma-Fuma 5 km [3.1 mi] and at Malela still 4 km [2.5 mi]—long topographical views were impossible because of the earth’s curvature. On the next stretch of river, the braided or divagante section of the river, where sights of 2 and 3 km [1.2–1.8 mi] were easily possible from island to island, the drawback was that the continuous erosion of the shoreline in the flood season resulted in the frequent and random disappearance of established bench marks. Placing bench marks and beacons further inland, away from the unpredictable erosion, was often impossible due to the swamp-like nature of the soil and the mostly impenetrable undergrowth. Further complicating surveys was the fact that there are no high points or mounts that overlook the surrounding topography, while the lush vegetation is always tall and exceedingly difficult to cut through (Fig. 17.9). In the last section, between Boma and Matadi, there are numerous hills, allowing the easy establishment of a hilltop triangulation. However, while climbing the mountains in the dry period is easy, in the rainy season the trek is arduous due to the often-high and sharp-leaved vegetation that cuts hands and face. The result was that in the braided section and between Banana and Malela, the beacons needed to be elevated—as metal pyramids—as ground stations were rarely

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The Topographical Methods

135

Fig. 17.9 Reference Points would often disappear in the flood season, with the result that with every survey new ones needed to be erected (and coordinates calculated). As an example, we see the markers within 2 years—1940 and 1942—and their evolution. The red ones are from 1940 that had disappeared by 1942, the new 1942 ones are in blue. Also notice the hydrographic ranges covering the Camoëns Pool, emanating from signals placed on Birds Island

practicable. Methods using short sights and multiple bench marks were a necessity as the beacons did indeed frequently disappear in the river flow. Because of the tropical climate, fieldwork was always tedious, very much time-consuming, and transport from one point to the next was rudimentary. From a surveyor’s point of view, one also must consider that theoretically one works from the large to the detailed. But such a situation was in practice not always achievable. Due to the priority list, small surveys sometimes took precedence over the larger work. This was no truer than along the Maritime Congo River. Oceangoing vessels had to navigate safely upstream, while a comprehensive colonial triangulation network was still in the making. Thus, between 1926 and 1932, the maritime section of the Congo was covered simultaneously by different triangulation chains—“un canevas” in French—of the first and second order,6 after which more detailed and subsequent chains of the third

6 “First order” refers to the highest level of accuracy in the survey network. It relates to the primary, often nation-wide survey, done with the most accurate instruments available.

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order were completed by the SVN. The entire network was then taken over, completed, and recalculated by the IGC in 1961. Further bench marks and beacons were later established through resection from the existing reference points. Due to the unique nature of the terrain and the multitude of islands in the river, using the “approximate point” or satellite station method7 seemed the most practical way to resolve the topographical problems.

7

One can easily measure an angle to a church steeple for instance, but it would be impossible to set up a station over it. So, a trigonometric method exists to set up a station nearby, measure the appropriate angles, and then transfer these coordinates to the inaccessible reference point.

Chapter 18

A New Navigation Channel in the Making

Abstract By the end of the First World War Jules Nisot, hydrographer in charge at the time, noticed a change in the customary fairway. The river appeared working toward a new thalweg. He eventually proposed to “assist” the river in its evolution and dredge a new fairway through the Fetisch Rock Pool. The authorities decided to follow his advice and by 1925 the navigation channel from Malela to Boma boasted a minimum depth of 8 m. This drastic intervention though had its repercussions further downstream. In the late 1920s, the winding Camoëns Bend became dangerously contorted and eventually in 1933 the thalweg broke through into the Mateba Downstream Pass. From 1926 on the riverbed in the entire braided section was surveyed on an annual basis. Keywords Nisot Pass · Mayaudon Pass · Fetisch Rock Pool · Camoëns Pool · Bulikoko · Katala · Itten G · Sasonoff G

18.1

The Nisot and Mayaudon Passes

To gain 80 cm [2.6 ft] in depth, the amount of sediment dredged annually grew by a factor of three in a decade. Recognizing the growing problem, the colonial administration in 1921 acquired a third dredger, named Congo,1 a vessel slightly larger than Boma. Jules Nisot, who had spent two tours in the Congo as Master Mariner of the yacht Hirondelle, returned in 1909 as Chief Hydrographer of the Lower Congo. In that capacity, between 1918 and 1920 he surveyed in detail the Fetish Rock Pool. Comparing the various charts, he noticed that the southern thalweg—the Portuguese Pass—showed a tendency to dig itself a new path, straight through the pool, instead of around the Penfold islands. He recommended his superiors to help nature and dredge a new pass, straight from Fetish Rock to downstream Penfold Head, into the Congo Yella Deep (Fig. 18.1).

1

Congo: Built at L. Smit & Zn in 1914. 55 m long, 9 m wide, hopper volume 525 m3. Sold to Min. of the Colonies in 1916.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_18

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Fig. 18.1 The Nisot Pass (today called Kindu Pass) project in 1920 and October 1924. The newly dredged pass was 5.2 km [3.2 mi] long with a minimum width at minus 8 m of 55 m [a width of 180 ft. at minus 26 ft], 125 m [410 ft] at the surface. The result was that minimum draught to Matadi increased from 5.8 m [19 ft] to 6.7 m [22 ft]. (Based on Devroey & Vanderlinden, 1951: “Pool de Fetish Rock”)

After Nisot’s retirement and departure in 1920, the proposal was further studied and by September 1923 it was agreed to follow Nisot’s second proposal, to dredge from the West Deep to Birds Deep, west of Ducks Island instead of to the Congo Yella Deep, east of Ducks. With three dredgers, two tugboats, and four hopper barges2 at its disposal it took the Waterways Department a year to accomplish the task.3 Depth in the new fairway was now always 8 m [26 ft] but the work had taken its toll: The Boma dredger had to return to The Netherlands for urgent repairs. Hydrographer and Master-Mariner Joseph Claeyssens, who was to leave the Congo into retirement in 1925 on board a luxury “ville” boat, instead was ordered to take the dredger back to Europe, an uncomfortable and arduous voyage that took him and his Black crew 53 days (Fig. 18.2).

2 Tugboats Flandre and Wallonie (built in 1918) and four dump barges, two of 200 m3 & two of 300 m3 capacity. 3 Enough sediment was removed to raise Central Park in NY by almost 1 m [3.3 ft].

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The Nisot and Mayaudon Passes

139

Fig. 18.2 An overview of the divagante section with the location of the various sub-maps in this and the following chapter

The streamflow in the years between 1910 and 1925 had been favorable for dredging operations as the crews could take advantage of prolonged periods with predominantly low water levels in the divagante reach. Cutting a new and 5-km [3 mi] straight path through the Fetish Rock Pool would inevitably have it consequences in neighboring channels. While the Northern Pass along Mateba Island had been silting up, over the ensuing years the Hippos islands were breaking up due to a steadily increasing instream of water along the northside of Birds Island that started complicating navigation in the northern Camoëns Pool by introducing cross currents at an already critical curve in the fairway. Between 1924 and 1936 crossovers in five separate locations in the pool needed to be dredged and between 1930 and 1933 the Hippos islands had split so far apart that the main flow broke through and the thalweg abandoned the southern path to join up with the Mateba Downstream Pass. In 1930 the crossover was almost in the same spot as in 1927, but the fairway had become contorted immediately D/S. Three years later the thalweg had broken through into the Mateba D/S Pass, thus creating a much smoother fairway. Unfortunately, the crossover had moved back U/S, toward Birds Island. By 1936 the Reopened Channel had changed course, digging into the Hippos U/S Island and depositing the sediment across the channel, around the Hippos D/S Islands (Figs. 18.3, 18.4, 18.5, 18.6, and 18.7).

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Fig. 18.3 The evolution in the Camoëns Pool in five charts, over a period of 12 years. Notice how the Camoëns Crossover moved over the years, posing a constant challenge. While in 1924 the Camoëns Crossover was situated at the end of the Congo Yella Deep and, further D/S, vessels used the Bulikoko Pass. (Based on Devroey & Vanderlinden, fold-out II, 1951)

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The Nisot and Mayaudon Passes

141

Fig. 18.4 In 1927 the Camoëns Crossover had moved downstream, past the elbow. This had a negative effect on the Bulikoko Pass, but widened the Monro Pass, which, as a result, became the preferred navigation route

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Fig. 18.5 Another three years later, in 1930, the crossover had stayed in place, but de fairway further down, along Hippos D/S, had become contorted and restricted as the Mateba Pass flow was slowly gaining importance, but still had a crossover south of the Mateba Grand Isle

While in 1924 the Nisot Pass connected West Deep with Birds Deep, by 1933 a crossover was forming near Ducks Island as Birds Deep was retreating. The situation was rectified by extending the Nisot Pass south, and this extension was called Mayaudon Pass (Figs. 18.8 and 18.9).4 It is interesting to note that between 1925 and 1938 the total volume of dredged material went from 500,000 m3 [653,940 yd3] to 1,550,000 m3 [2,027,203 yd3]—a threefold increase—within 13 years. Also notice the location of the Special Hydrography Service Compound (SHS) on Mateba Island, near the Mateba Village. This saved the survey crews a daily commute back and forth Boma. Later, the compound would be abandoned in favor of a large houseboat that could be towed to any location where the crews were working. 4

Mayaudon, Joseph, A (1895–1934). After a career as mariner before and during the First World War, in 1923 he joined the Hydrographic Service in Boma where in 1929 he became head of the service.

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The Nisot and Mayaudon Passes

143

Fig. 18.6 By 1933 the morphological change was complete: the southerly route had silted up, in favor of the Mateba Pass. On the positive side, this allowed for a much smoother navigation route. Unfortunately, a new obstacle started to manifest itself: The crossover had reappeared back upstream this time, between the Congo Yella Deep and the Camoëns Pool

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Fig. 18.7 By 1936 the so-called “Reopened Channel” had been very active, thereby pushing sediment into the fairway and had it bend southward. As for the dredgers meanwhile, keeping the Camoëns Crossover deep enough remained the priority. This 12-year snapshot brought home the utmost importance of continuous bathymetric surveillance to avoid unnecessary and expensive dredging operations

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The Nisot and Mayaudon Passes

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Fig. 18.8 The evolution of the navigation channel in one graph. It suggests that the combination of the “Reopened Channel” at the top end of the bight and the improved flow through the Congo Yella Deep—due to the Nisot Pass—pushed the thalweg “over,” eventually forcing it into the northern Mateba Pass and abandoning the Monro & Bulikoko passes

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Fig. 18.9 This chart is a colorized version of a compilation of five hydrographic maps, each at a scale of 1: 10,000 of different areas of the divagante region, made in 1927 and 1928. For clarity, the soundings have been omitted but the thalweg/fairway is indicated. There are several ones, but only the most southerly one—including the use of the Nisot Pass—was deep enough for large vessels. Notice that the local coordinate system at the time still had its origin in the so-called “Geo-Creek” on the Angolan coast. The secondary thalwegs along the northern route had a few tricky crossovers: the one in the west near Pelicans Islet had only 6.2 [20.3 ft] and 5.4 m [17.7 ft] in the dry season, while the ones between Turtles Archipelago and Birds Island in the east had only 4.4, 5.2 and even 4.2 m [14.4, 17 & 13.8 ft] of clearance. The southerly route is almost ready to break through between the Hippos U/S & D/S islands and join the Mateba downstream fairway which offered sufficient depths for large vessels without human intervention

Chapter 19

The Mateba Deceiving Bend (Barrage du Faux-Bras de Mateba)

Abstract To stabilize the ever-shifting thalweg, engineers had been looking at constructing fixed river works to “tame” the unstable behavior of the river. The idea was to close certain by-channels, so as to direct the main flow into a single, 9.10 m deep, channel. Finally, in 1929 the decision was taken to start the first phase of the plan, closing the so-called “Deceiving Bend” of Mateba. After several delays and technical changes, in 1934 work started but after many difficulties, the next year it was decided to start all over again, using a different technique. Nevertheless, work dragged on into the summer of 1938 and in the final count, the costs had more than doubled over the initial estimate. Keywords Mateba Deceiving Bend · Faux-Bras Mateba · Sheet Pile Dam · Limnigraph · Barrage As sandbars in the various channels between the shifting islands continuously move around, already in 1902 engineers were contemplating measures to stabilize the fairway by means of groynes and closing side channels. Such measures, it was expected, would restrict the lateral movement of the fairway, and reduce the dredging operations to maintenance dredging without the worry of where the thalweg would manifest itself after the next flood season. Dredgers could only improve the fairway in certain spots, but it was recognized that creating an entire artificial fairway in the given circumstances was just impossible. From 1927 on a detailed plan was studied that would create a fairway, 9.10 m [30 ft] deep at all times and 600 m [1970 ft] wide, that would follow a path from Fetish Rock, through the so-called Reopened Channel, toward Ziamanganga (Convensaingh), Mateba D/S and Quissanga (Kisanga). This projected fairway would cut the existing route from 45.5 km [28.3 mi] to 37.5 km [23.3 mi] or, shortening it by 20%. To reach that goal the deceiving bends would have to be closed by semi-permeable, fascine dams and a few groins along the remaining main channel would have to be constructed. They would all have to be made of the same components, making use of locally available material. The idea behind this method of construction was to allow for some initial flow through the dams to continue, as such only slowly augmenting the flow through the main channel while the fascine © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_19

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The Mateba Deceiving Bend (Barrage du Faux-Bras de Mateba)

dam would close gradually by sand deposition around it. The fascine groins would be held in place by a series of dolphins1 consisting of a series of concrete piles, driven in the riverbed. As a base layer, to prevent riverbed erosion, the bottom would be protected by osier mattrasses, weighed down with riprap. It was a proven method in Europe at the time but would be new to Central Africa. As it was a complex and expensive proposition, the Minister of the Colonies in 1929 set up a commission of experts, including four foreign ones, to get a closer look at improvements of navigation on the lower river in general. Its advice was, due to the limited knowledge of the evolution of the river morphology, to act cautiously and only take one step at a time, giving the river time to adjust and observe the results before continuing with the next phase. The U.S. member of the commission, an expert on the Mississippi River, advised to start construction of the dam through the upstream deceiving bend along Mateba Island and install three groins opposite, on the Pelican shoals, abutting Birds Island. To limit erosion of the Mateba Deceiving Bend riverbed, it was advised to start construction of the dam from the Turtles Islet No. 1. It had been calculated that between 5 and 7% of the total flow passing by Fetish Rock was “uselessly” diverted through this bend. When in November 1929 the Colonial Administration got the green light to start the first phase of the project, for unknown reasons a couple of major changes were proposed. First the dam was to be build, not at the upstream edge of the Islet No. 1 but further downstream in the channel, where the riverbed was shallower. Secondly, the fundamental composition of the dam itself would be altered. Bed protecting mattrasses would still be provided for, but the dam was to be made of timber framing (trestle dam) and closed with standing tree trunks like a needle dam, a procedure often used at the time. A year later the river morphology along the fairway nevertheless had evolved positively and it was decided to let nature run its course. That thought disappeared at the end of 1931 when it became clear that these expectations would not be fulfilled (Fig. 19.1). Another year still passed before a second technical commission investigated the proposed dam site. A hydrographic survey concluded that the dam would have to be 1000 m [3280 ft] long through maximum depths of 3.50 m [11.5 ft] with an average depth of 2.25 m [7.4 ft]. Test borings revealed a sandy riverbed, at least 10 m [33 ft] thick. This time three variants of dam materials were considered: (1) A semipermeable dam with bottom mattrasses, a wooden framework, and needle dam. (2) A waterproof dam consisting of large, rock-filled “rolls” or gabions, to be delivered on site and rolled overboard from a doubled-up barge acting as construction platform. (3) A steel sheet piling dam made up of 10 m [33 ft] long, interconnected piles. Of the three proposals, the consultants advised that the third option was the least favored. It was not only the most expensive one, but they were also of the view that 10 m long piles would not be enough, that scouring at the

1 Dolphin: Originally a mooring post, comprised of a vertical ‘kingpost,’ supported by three shoreposts, all driven into the riverbed.

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The Mateba Deceiving Bend (Barrage du Faux-Bras de Mateba)

149

Fig. 19.1 First attempt at construction of the dam. In the background the pile driving pontoon, in the foreground a barge with a load of sheet piles. Due to severe scouring at the head of the work, the crew had changed to a sawtooth pattern with supporting T-reinforcements (see arrows). Upstream is to the right. Photo taken from the second pile driver. In the background Islet No. 1. (Devroey Family Archive)

working end of the dam would be excessive and they even feared that eventually the structure could be overturned by the strong flow in the flood season. All advice was to no avail. In the spring of 1934, the ministry of the colonies decided to proceed with the construction of a cantilever steel sheet piling dam. Was this decision influenced by the fact that the steel piles were produced in Belgium? We will probably never know. To avoid scouring at the working end of the dam2 it was foreseen that the dam would proceed by 10 m [33 ft] a day (or driving 12 piles a day), as such trying to outrun the potential scouring at the working head. Nevertheless, if indeed scouring would develop in front of the piles, it was assumed that unhooking of the sheet at that point and continuing the pile driving in a sawtooth wave would minimize the problem.3 Scouring of the riverbed means undue removal of sediment caused by fast flowing water, in this case because of progressive narrowing of the river channel. 3 This would lengthen the wall by 25% and as a result diminish the flow rate and scouring action per running meter. 2

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In April 1934 almost 2200 sheet piles of assorted sizes were ordered, together with various accessories, including 10 driving heads. The colonial waterways service would provide barges, pontoons, tugboats, and shuttle ferries needed for the project. The driving crew would be composed of a section-chief, two “drivers” and some 30 Indigenous laborers. On the 3rd of July 1934 the work started, and it was planned, with two pile-drivers, to finish within 3 months. Work was started in the center of the channel, with each piledriver working its way toward the opposing shore. Within the first week the crews noted that severe scouring at the head of the works was reducing the embedment of the 10-m-front pile to an unacceptable 95 cm4 [3.1 ft]. Continuing in a straight line would mean the imminent collapse of the wall. According to the plan, to minimize the scouring, it was decided to unhook the advancing wall and start a sawtooth course. At the same time, work on the north end of the curtain was halted to concentrate all efforts and manpower on the side towards Turtles Islet No. 1. However, by mid-August the 10-m-long piles never achieved the (then required) minimum 1 m [3.3 ft] embedment. The dam had to be supported by upstream anchors while the workshop in Boma fabricated 12-m-long [39 ft] piles by welding two 6-m-long piles and 8 + 4 m piles together. Both types were to be driven-in alternatively so as not to create a weak spot in the wall. However, severe scouring remained a problem and the workshop in Boma had to start fabricating 16-m-long [53 ft] piles (combining 8 + 8 and 10 + 6 m piles). Even with 16-m piles the problem persisted and frequent unhooking of the sheet wall remained a necessity. On top of it every change in direction needed the wall to be secured with heavy timbers, bridging the change in direction and extra upstream anchoring was needed. With the piledriver pontoon, now on the downstream side of the wall as an extra support of the advancing work, it became enormously harder to move it to drive the next pile. By the end of September 1934, the driver had reached the islet No. 1, and driving was continued on land with a wooden driver frame. Having lengthened many piles by welding shorter ones together, no piles were left to finish the dam on the north side, toward Mateba Island (Fig. 19.2). Mid-November a second order of 620 piles arrived, this time all 12 and 15 m [39 & 49 ft] long, but they too lost embedment due to violent scouring during the flood season. Even while driving the piles at the working end, they started to bend under the water pressure, became uprooted, and were carried away by the strong current. A rethinking of the working methods became imperative. The section chief had warned the Belgian authorities of the instability of the sandy riverbed and proposed to drive the piles all the way into the riverbed, thus preventing bed erosion, and then later extract each one consecutively by 1 m [3.3 ft] at a time to avoid scouring. A test run in October had shown that this procedure was promising. To drive the pile under water, a fake piece of pile—up to 6 m [19.7 ft] long—was fabricated that would fit on top of the real pile once it reached the water. The only

4 Today, as a rule of thumb, piles need to have 2/3 embedment and 1/3 free height. So for a 10-m long pile, that would mean an embedment of 6.5 m.

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151

Fig. 19.2 The evolution of the construction of the Mateba Dam over 4 years. What nobody knew at the time, was that just south of the dam, in the thalweg, a rock formation, buried in the river bed, would now and then be uncovered at flood season, disrupting the main river flow over a long distance, making the navigation channel permanently unstable

disadvantage of the process was that the driving energy was partly absorbed by “fluttering” and abnormal heating of the fake pile. Following the successful tests, work was resumed on March 1st, 1935. Starting at the Mateba Grand Island and working its way southwest, 3 months and almost 600 piles later, the piledriver pontoon arrived at the section, built the year before and without any appreciable scouring. Since examination of the original section revealed several ruptures, it was decided to continue the new dam towards Islet No. 1, on the upward side of the existing curtain, through a shallow riverbed already established because of silting up since the first attempt. Since the work was now more or less sheltered in front of the original dam, the pile driver covered the last 406 m [1332 ft], driving an average of 11 piles a day in 48 days. The work was continued on the islet itself for another 186 m [610 ft] finishing on the 3rd of October 1935. Since by now no piles were in stock anymore, it was decided to extract some of the piles from the

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original, zigzag attempt to replenish the stockpile. As such, by the end of February 1936, almost 400 piles were retrieved. All that was left to do was to raise all the piles from underwater to their final height. Fear of scouring would be unfounded as the “sunken” curtain now functioned as a cut-off wall for the river flow. By the end of the month nevertheless two leaks in the pile curtain were detected where water undercut the footings. It took well into the summer of 1936 before the sheet piling in those weak spots could be doubled up. The final phase of the enterprise started in the spring of 1936. One of the first findings was that, when the pile was lifted to the bottom of the pontoon, the water rushing over the pile immediately disappeared under the pontoon (the driver again being anchored downstream of the curtain). That violent flow now created severe scouring on the downstream side, by as much as four meters [13 ft] in half an hour. The crew was forced to bring the pontoon round and work from the upstream side, a procedure that made working much more difficult and posed the risk that the pontoon and its precious load could be pushed over the dam (Fig. 19.3). It took until July 1936 to lift all piles to their projected elevation. By then, on the Grand Island Mateba side, only 200 m [656 ft] of curtain still needed to be lifted. The critical stage had arrived. Whereas before the flow through the deceiving bend had

Fig. 19.3 The piledriver, right, with the hammer (center) ready to drive a pile. Left a barge with a load of sheet piles. The arrow at the bottom points to the sheet piles already driven. (Devroey Family Archive)

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been distributed over 1000 m [3280 ft], now it was concentrated upon these last 200 m [656 ft]. In the calmer waters, between the upstream and downstream side of the sheet piling, the difference in water level was 31 cm (a foot) but in the remaining gap the flow was now so violent that the layer of water spilling over the still submerged pilings reached two meters [6.6 ft]. On the 8th of July, after investigation, between piles 22 and 38, the water passed under the curtain. Immediately the affected piles were driven deeper, and it looked as if the danger had passed. Then, the next day, 50 m [165 ft] to the southwest, a set of piles suddenly started bending. The failure was corrected the next month, but problems kept arising. In the following weeks, in four different spots, the sheet piling had to be doubled up because of new leaks developing in the northern (near the Mateba Island) section of the curtain. Since in February of the following year the weekly surveys did not show any appreciable changes in the riverbed it was decided to extract the remaining salvable piles from the original dam, built in 1934, to replenish the stockpile. By mid-1937 the 120 m [393 ft] gap in the dam was still open, but the engineers concluded that closing it was not an urgent matter as flows through the bend had stabilized. It was decided that in the spring of 1938, the gap would be closed by extending the sheet piling in a curve northward (downstream) to end almost 200 m [656 ft] downstream of the original landing spot on the Mateba Grand Island, a location that was deemed more stable than the original. A month after restarting the work, on April 7th, 1938, the downstream riverbed had silted up so much that it became necessary to move the pontoon again to the upstream side to continue the pile driving operation. By July 25th, the piledriver had reached the Mateba shoreline and work was continued for another 90 m [295 ft] inland to form a solid anchor point for the dam. With the work finished in August 1938, 4 years after the initial start, the crest of the dam would surface in the low water season with a freeboard of 40 cm between the up- and downstream side, while being submerged in the wet season by 1.50 or more meters [5 or more ft]. The question now being if any dangerous scouring would occur in the flood season. Overall, the evolution of the riverbed in the vicinity of the Mateba Deceiving Bend had evolved as expected: shoals had been built up- and downstream of the partly finished dam with scouring in the still open section of the bend. In the main navigation channel, between Islet No. 1 and Birds Island (the Mateba U/S Pass) major changes had also taken place, but it was unlikely they had been influenced by the construction of the dam. That area was already known for its morphological dynamic behavior. It would take another four decades before the cause of this volatility in the pass would be revealed. While flow measurements in the early 1930s had indicated that 5–7% of the total flow was lost through the deceiving bend, flow gauging in 1937 and 1938 indicated that the diversion had dropped from 4% to as low as 1.4%, depending on the time of year when the measurements had been taken (wet or dry season). In the end the total expenditure on the project amounted to almost seven million Belgian Francs, of which close to four million went to the purchase of the sheet piles. The original estimate, in January 1934, had been 2.8 million, raised in October of that year to four million, but that included a second order of sheet piles (Fig. 19.4).

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Fig. 19.4 The dam stood up for several years but by the 1970s it had disappeared from the maps. The location is still known as “barrage” and a tidal gauge (in the background) and a shaky limnigraph were still standing in the 1970s, next to a few remains of sheet piling. As will be noticed, the piles at this point were pulled up alternatively. (J-J Peters Archive, Flanders Hydraulics, Antwerp)

Alexandr Khokhloff, who did major hydrographic work on the river before and after the Second World War, would write in 1964: Taking into account the only attempt at regulating the river—the damming of the Faux Bras Mateba that has gobbled up eight million francs for which the result was absolutely nihil”— it is therefore imperative to study any change to the fairway on a scale model.

In hindsight it had indeed been an expensive experiment. By 1941, 250 m [820 ft] of sheet piling, embedded in the Islet No. 1 had already been swept away by the relentless scouring. Creating an impermeable screen with sheet piles bought from Belgian manufacturers would have been good for Belgian industry but using locally sourced fascines would have created a pervious screen that could have been naturally closed by accumulating sand. Nonetheless, if that kind of dam would have survived the relentless river flow is equally dubious.

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While in 1929 the minimum depth in the fairway had been a precarious 6.55 m [21.5 ft] in 1937 the minimum was over 8 m [26.5 ft] with 8.38 m [27.5 ft] for over more than half the year. Strangely enough this gain was not attributed to the closing of the deceiving bend but to the policy of “directed dredging,” especially the Nisot and Mayaudon Passes through the Fetish Rock Pool. As it was estimated that the typical freighter along the west coast of Africa, for a long time to come, would have a deadweight of 7500–8000 tons with a draught of 7.60 m [25 ft], any further improvements in the braided section of the river by closing side channels or adding groins in the main channel was, for the foreseeable future, deemed unnecessary. Chief engineer for Public Works for the Colonies, Égide Devroey, suggested at the time (1938) that, before attempting further improvements, it might be advantageous to study any deepening of the Luango Channel as this waterway circumvented the braided section and lay entirely on Congolese territory. The same suggestion as Van Deuren had made 10 years earlier. We will further talk about that later (Fig. 19.5).

Fig. 19.5 The distribution of the Congo River discharge through the various channels of the breaded section, over time. Black figures relate to 1938, those in green to 1956 and in red to 1966. The figures suggest that in that period the flow on the Congolese side of the river had diminished in favor of the Angolese side (See esp. the figures for the North and South Pass at the bottom of the chart)

Chapter 20

Difficult Years

Abstract Before 1935 the border between the DRC and Angola, in the braided section of the river, had never been officially established. In that year, a protocol between Portugal and Belgium was drawn up, but it never got ratified by both parties. During the Second World War, bathymetric surveys of the river were limited to the immediate areas along the existing fairway. The work conducted suggests that some of it was related to the transport of strategic goods from the Congo to the USA. With the return of Khokhloff to head the waterways’ service in 1946, the department got back on its feet and in the early 1950s modern hydrographic methods and equipment were introduced. By 1954 the passes, dredged in the 1920s and 1930s, became alarmingly unstable with sharp bends and dangerous constrictions. Keywords Lisbon Accord · Angola-DRC border · Jentgen J · Shinkolobwe · Ville Boat · CMB

20.1

Where Is the Border Exactly?

Most of the land borders of the Bas-Congo were physically established early on, between 1897 and 1901. Strangely enough, the border between the CFS and Angola in the south, from the Atlantic Ocean to Boma, was never described in detail. The only bilateral text available on the subject1 stipulated: In the Congo River, from its mouth to Noqui, the border between both states will follow the centre line of the navigation channel followed by ocean-going vessels. This channel at present [1891] leaves the islands of Bulabemba, Mateba and Princes Island to the right bank2 [CFS] and to the left bank [Angola], among others, the islands of Bulikoko3 and Sacra Ambaca.

1

The Convention of Brussels of May 25, 1891, explaining, precising and rectifying the Convention of Berlin of February 14, 1885. 2 Left and right banks assume the observer is looking in a downstream direction. 3 Bulikoko: African Pheasant. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_20

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For the section between Banana and Malela, and upstream between Princes Island and Noqui, there was no doubt about the country borders, as the river follows a single path between those places. It was another matter in the braided section where there can be two or even three thalwegs and, moreover, it can take the most curious twists and turns. As such the original text was quite vague and owing to this, over the ensuing years, became subject to interpretation. It is clear from the second sentence what islands are on “who’s side” but, according to the first sentence, the border will follow the navigation channel. Since the navigation channel, in the braided section at least, can change considerably over time, does the border then moves with it? That would mean that at certain times one or more of the aforementioned islands would temporarily become enclaves in the opposite country. It appears that the European colonial powers, signatories at the time, believed that large vessels traveling the Congo River should always be able to travel a bi-national route, wherever that channel took them. It would offer them freedom of navigation as indicated in earlier and similar treaties.4 Assuming that the colonial powers, Belgium and Portugal, wanted to clear up this ambiguity, in 1935 a so-called “Lisbon Accord and a Ponta da Lenha Protocol”,5 were prepared in which a fixed border was proposed. This boundary would follow a broken line in three segments, connecting four pre-determined points in the river, from Boma to Malela and numbered I to IV. By 1967 the Accord had not been ratified by either the Republic of the Congo or Portuguese Angola.6 The current situation is unknown (Fig. 20.1). Early on in my research I came across a detailed 1938 map of the Bas-Congo, Sheet VIII “Banana” at the scale of 1:100,000. It contained many shore beacons and signals and interesting enough, only nine of them did bear the designation of Borne [bench mark] and they were numbered from I to IV with each subdivided into “a” and “b” (there is one “c”). These bench marks, following their corresponding Roman numerals, were in four pairs (plus one), between Fetish Rock and Malela. Months later, on the SVN hydrographic charts between 1940 and 1950, I found a broken line in the river, connecting four points (I–IV) and indicated as frontière [border]7 without further clarification. Superimposing this line on the 1938 map revealed that each “river” point corresponded with the aforementioned bornes in such a way that the bench marks could have been used to determine the not-materialized boundary corners in the river through triangulation.8 4

I refer here, among others, to the Vienna Congress Treaty of March 1815, Annex XVI regarding navigation on major European rivers and the Convention signed in Mayence, March 31, 1831, regarding the Rhine River. For more on this subject, see Ngoma Khuabi (2014). 5 Lisbon Accord of May 13, 1935, and the Ponta da Lenha Protocol of August 20, 1935. For more details see: Sterling A, Rombouts C & Charlier J (1967) Rapport de mission . . . p. 58–66. The original documents I was unable to find. 6 The DRC was then called the “Republic of the Congo.” Angola achieved its independence only in 1975. 7 On the 1954 chart this line had disappeared again. 8 With the advent of gps receivers, this procedure would now be superfluous.

20.1

Where Is the Border Exactly?

159

Fig. 20.1 The 1935 proposed “Four-Point” nautical border and its relationship with the bench marks as set out in the 1938 Belgian topographical map. The drawing also depicts the original Portuguese measured baseline and the primary Portuguese triangulation points from which the Belgian land surveyors determined the coordinates of their bench marks on Congolese territory. Cooperation between the Belgian and Portuguese surveyors was always amicable

Assuming this is indeed the “1935 Lisbon” line, a few observations are in order: In 1952, a respected Belgian judicial scholar, P. Jentgen,9 favored an interpretation of a so-called “mobile” border, whereby the islands would remain national territory of their respective countries, as described in the late-nineteenth century acts, but where the “wet” border would always follow the main passes in use at any given time. His argument was that the original signatories always intended to allow vessels of the riparian states to stay within national territory while following the principal navigation channel, wherever in the braided section that would lead. As a result, depending on the fairway in use, certain islands could be considered temporary enclaves in the other’s territory. With the riparian countries having gained their independence since the original acts and accords were laid out, the judicial situation has become even more complex as the Belgian colonial and later Congolese governments have done much work—and spent a lot of money—on studying, equipping and dredging parts of the river that, according to the 1935 proposals, would in essence be on foreign territory. A “mobile” border would in principle solve this problem but create others. What if soundings suggest that an alternative fairway is developing? Which authority will decide to switch, and when? What if an emergency occurs in the intervening period? Enclaves, as a rule, are avoided by international law, as they can be a cause of all sorts of unexpected difficulties. So, a fixed border would be preferable, but the 1935 “four-point” line was quite rigid, in the sense that between point III and IV, the line passed close in front of the 9

Jentgen, Jean P D. Les frontières du Congo-Belge (IRCB, 1952).

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DRC Katala Island, too close for international shipping to freely maneuver. Understandably, with 1935 technology in mind, it would have been quite complex to determine a border comprised of more points, something that, with today’s technology, would not be a problem. Thus it might be prudent to revisit the 1935 proposals and draw up a more detailed agreement.

20.2

The War Years

1940 was of course a disruptive year for the entire world. This also had its impact on the work of the survey crews of the department of navigable waterways in Boma. From December 1939 to May 1940 hydrographic surveys were conducted in the braided section of the river but only along the main fairway in use at the time. The so-called Portuguese passes were not covered as was the Luango Channel along the north of the Grand Isle Mateba. After the month of May there was a hiatus until in August the downstream end, from the Lawrence islands to Ponta da Lenha, was surveyed (Fig. 20.2). Large vessels going upstream would hug the Katala Island until Ponta da Lenha from where they switched temporarily to starboard to hug the Bulikoko islands. In front of Katala depths were not an issue. They ran in places to 20 m or more. Along Bulikoko the available depth shrank to 15 m. Past the Smugglers Shoals the captains had to cross the channel again and head towards the southern headland of Mateba, to enter the Mateba D/S Pass. Here depths would reach an unstable threshold of 9 m after which, entering the Camoëns Pool, the fairway improved to 20 m until a sharp

Fig. 20.2 The divagante region in 1940

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The War Years

161

bend to starboard, in front of Birds Island, where the fairway narrowed, and depths would be reduced to barely 8 m. Then, when nearing Papyrus Island, ships had to make a wide turn to port (left) to clear Palm Head on the Angolese mainland. Here the Congo Yella Deep reached depths of 20 and more meters, but not for long. Ocean going vessels now needed to hug Birds Island on their port side and continue in a straight line for almost 10 km through the Mayaudon and Nisot Passes toward Fetish Rock. Here again it was highly recommended not to stray outside the buoyed fairway. Red and black buoys were now closer together than before. Only when reaching Fetish Rock did the channel widen and deepen again, but now new dangers lurked under water. Near the well-recognizable rocky outcrop, the submerged Jorgensen Rock loomed, while some 3 km on, the submerged Winton Rocks created dangerous turbulence. On the opposite and Congolese side, the Triquet Rocks posed a similar danger. Another 4 km on, along the Angolan island of Selonga, other underwater rocks again created eddies of which vessels best stayed away. But at least, Boma was now in sight! For ships with shallower draughts, say 5–6 m, they could use a more direct route, from the Mateba D/S Pass into the so-called Reopened Channel to the north of Birds Island. However, this required good knowledge of the river currents and water levels in this area as vessels needed to cross over the Reopened Channel into the Mateba U/S Pass. The plus point was that this direct route shaved off 5 km from the main, 8 m deep, fairway through the Fetish Rock Pool. Four tidal gauges kept track of the water level along the route: one on Katala Island near Ponta da Lenha, one on the south shore of Mateba Grand Isle at Ziamanganga (Convensaingh), one on the SE shore of Birds Island and one near the Monolith, west of Boma. In general, between 1931 and 1950 the fairway had gradually improved. By 1944 a minimum depth of 8.50 m [28 ft] was achieved. Between 1944 and 1948 a change in passes required a steep increase in dredging volume, from 550,000 m3 in 1944 to 2.1 mill. m3 in 1947, while before an average of 1.1 mill. annually had proved satisfactory. Despite this, the hard points in the river, combined with the nature of the crossovers, had a negative influence on the natural sediment transportation of the river (Fig. 20.3). A quick glance at the 1942 chart suggests that not much had changed in the past 2 years. Yet, on closer examination, a number of smaller islands had disappeared, and bigger ones had changed their shape. As for new islands that had emerged, I want to draw the attention to the new islands that had surfaced on both sides of Birds Island. They were a build-up of the shoals from 1940. Out of the Flamingo Shoal an island with the same name had emerged. Further downstream, the eastern Bulikoko islands had changed their shape as had the Lawrence Islets fronting Malela. In the upper bight against Mateba Island the configuration had evolved dramatically. The Turtles Archipelago had undergone a radical change. Especially of note is the upstream head of Islet No. 1. It had eroded up to the steel sheet piling that was hammered in only a few years earlier. Instead, a new gully emerged: Fishermen’s Deep. Unfortunately, this diverted valuable flow from the important Mateba Upstream Pass to the south.

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Fig. 20.3 The region in 1942

Another example is the main Hippos Upstream Island. In 2 years, its upstream head had receded by 450 m. The island had gone from 8.35 ha to 6.24 ha, or a reduction of 25%. Notice the 1940 eastern landmark (red dot) that had disappeared in several meters of water. On the positive side, the island had gained a large sandbank on its downstream side. One of many indications that, in a dynamic and broad river environment, shoals and islands tend to morph and move downstream, or even cross the navigation channel . . . but not always! The fairway through this pass had now shifted from south of Hippos Upstream to north of the Island, but there was still a shallow crossover that needed to be dredged. While in 1940 the area of the so-called Portuguese passes, south of the Bulikoko Islands, had not been covered, this time it had been taken in hand and surveyed in October and November of 1942. Did the hydrographers expect an improvement in the navigability of the southerly route? Although the width of the Mayaudon and Nisot passes south of Birds Island had improved, it had deteriorated in the Camoëns Pool. In places the 8-m-deep fairway was barely 50 m wide. The eternal concern remained in the evolution in the Mateba U/S Pass. The Turtles Archipelago had broken up further, as had the Hippos U/S islands. In the low water season, more shoals had shown up, thereby breaking up the previously straight Mateba U/S Pass into two sections. A detail on the 1942 bathymetric chart (but for clarity depicted in Fig. 17.9), gives a rare insight into the way hydrographic surveys were conducted at the time. To cover the Camoëns Pass between the Camoëns Pool and Birds Islands, 13 radial ranges had been set up. Four of them radiated from the back range “E” on the south side of the island and passed through four equally spaced poles (Nos. 1 through 4) set up as the front ranges on the southern peninsula of the island. The captain of the survey boat only needed to keep “E” and one of the front range signals lined up while

20.2

The War Years

163

Fig. 20.4 The Luango (Maxwell) Channel as surveyed in 1943, the only time during the Second World War

his survey crew conducted subsequent sounding across the pass. A similar system, but then with six ranges across six poles (Nos. 5 through 10), radiated out from “Ninette Marker.” Three more beams were set up, but through secondary ranges. Overall, the ranges crossed the 8-m depth line in the pass at intervals of between 100 and 150 m [110–165 yds]. As we have seen earlier though, most sounding ranges throughout the reach were taken in parallel lines (Fig. 20.4). On the 1943 hydrographic map of the braided section, suddenly a surprise: while in the previous three war years no attention had been paid to the bathymetric situation in the Luango Channel, now a thorough survey of this river arm, entirely on Congolese soil, shows up.10 Over 3 months—from June to August 1943—the almost 40 km long channel had been charted. In a time when the colony had already been cut off from its homeland for over 2 years, it has to be assumed that the influx of new hydrographic technicians to relieve the ones on station had dried up and that consequently the annual river surveys would have suffered. However, in 1943 no less than 75 km2 of extra river had been taken on. What would have been the purpose of this extraordinary Belgian survey effort? One explanation might have a link with the now famous but then secret Manhattan Project. In the fall of 1942, the U.S. Government had signed a deal with the head of the Anglo-Belgian Company UMHK11 for the delivery of uranium from the Katanga region in the Congo. At the Shinkolobwe mine in Katanga this company

10 The land survey crew had established an inordinate number of signals along the shore: over a hundred conspicuous trees, bushes, poles and other were reference points (1 landmark per 75 ha of channel). This does not include the triangulation points that were established with greater accuracy before the signals had been chosen. Sounding ranges in the channel were run every 200 m. 11 Union Minière du Haut-Katanga.

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had been extracting pitchblende (uranium ore), extremely rich in radium. The mine had fallen in disrepair since, before the war, there was no real market for the product. Now the United States wanted to secure this strategic uranium source to keep it out of the hands of the Axis Powers. And here was a territorial problem. While the Belgian government was in exile in London, its adherence to the allied cause was never in doubt. In the first years of the war, the same could not be said of Portugal (and its colony of Angola). Since Portugal and Belgium, as colonial powers, shared the maritime section of the Congo River there could potentially develop a dispute over navigation on the river by allied ships. That would not be a significant issue on sections of the river where the fairway coincided with the borderline, like upstream between Boma and Noqui, but it could create a major diplomatic headache when shipping was using exclusive Angolese territorial waters, like the Camoëns and Fetish pools. Imagine Axis Powers getting wind of a shipment of uranium ore traveling through “neutral” waters! Such a potential, geopolitical incident suggests that the hydrographers in Boma had been instructed at the end of 1942 to survey the Luango Channel as an alternative shipping route to avoid having allied shipping plying territorial waters of a state with a questionable stance regarding the war effort. The urgency of the matter then apparently ebbed away as in the hydrographic charts of 1944 and 1945 the Luango Channel bathymetry was not included anymore (Fig. 20.5).

Fig. 20.5 The 1944 bathymetric map. Notice in blue dots the main navigation tripod beacons on land with their centerlines and, where these intersect, the blue dot that represents the “White Buoy,” which was there at the time

20.2

The War Years

165

By 1944 the positive bathymetric situation of the river was declining. The Camoëns Pass had not improved, and the so-called Reopened Channel was slowly closing again. The Mateba U/S Pass was drifting further west but had not made a breakthrough upstream from the Ntua-Nkulu Pass. It was still a secondary channel with limited depth in places and following a tortuous course. A lack of a long-range dredging plan in these difficult years was not helping either. Deepening the Mateba Pass nevertheless would shave-off several kilometers of the fairway between the ocean and Boma/Matadi (Fig. 20.6).

Fig. 20.6 The various sounding charts that had been made up to the end of the war had not been standardized, neither in scale nor in coverage or classification. With Khokhloff at the helm a much more streamlined system was introduced. This is a sample of chart assembly from the 1950s. From now on sounding charts were all made at a scale of 1:10,000

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20.3

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Difficult Years

Alexandr Khokhloff Returns

The 1945 Chart of the Malela-Boma reach is slightly—but importantly—different from the previous editions. The heavy-drawn, eight-meter [26 ft] bathymetric contour line on the earlier charts has been replaced by a similar heavy, but 10-m [33 ft] contour. The eight-meter is still there, but the 10-m now draws the attention. Freighters were getting larger and consequently, draughts got greater also. A wartime Liberty-class cargo ship for instance drew 8.45 m [27.7 ft] at full load, a Victory ship12 8.71 m [28.6 ft]. Inevitably, the new passenger liners to be build that would ply between Antwerp and Matadi would increase in size also. The new Albertville—the sixth with that name—built by John Cockerill in Hoboken, Belgium, and its sister ships Leopoldville (6), Elisabethville (3), Baudouinville (2), and Charlesville, all built between 1948 and 1951, had a deadweight of about 9433 metric tons and a draught of 8.40 m [27.5 ft]. Fully loaded they displaced 16,560 metric tons.13 These, colloquially called, “Congo Boats” would depart Antwerp every fortnight with destination Matadi. It took 15 days to make the one-way journey, including a stop at Tenerife (Canary Islands) and Lobito (Angola). Very democratically, they had only one class with all passengers having free access to all decks and public rooms. The difference in ticket price depended on the location of your cabin and the amenities in it.14 These ships made 17 knots [31.5 km/h], carried a crew of 150 and could accommodate 188 adult passengers and 19 children in 65 cabins. By the end of the 1950s, CMB ordered several cargo ships “MO-Boats” (all had a Congolese name, starting with “Mo. . .”) that had a draught of 9.30 m. In 1946, the Hydrographic Service was in disarray. Five years of being cut off from their families in occupied Europe had taken a heavy toll on the white technicians. Multiple resignations and several overdue retirements suddenly caused a severe staff shortage. Aleksandr Khokhloff,15 the Russian émigré who had worked for the Belgian Colonial Hydrographic Service in Boma between 1928 and 1934 returned to fill the breach. Despite his commendable service, he had been laid off in 1934 because of budgetary constraints during the global economic crisis. Three years later however he was back in the Congo, this time as a topographer in the mining region of Maniema, along the Upper-Congo. In 1947 Khokhloff saw his chance to get back on the water and that year he returned to Boma to lead the Hydrographic Service. In an unprecedented feat he

12

Of each class the CBMC employed seven from 1944 on. The last one was sold in 1966. From 1953 on, CMB vessels were built for a draught of 9 m. As a result, they needed a minimum of 9.15 m [30 ft] over the passes. Every 30 cm less meant a loss of 600 tons of cargo. 14 Single adults would pay between 18,500 and 27,900 BF [370–558 USD at the time] for a cabin with bath. 15 Khokhloff, Aleksandr A (1896–1974). Officer in the Russian Imperial Navy. Fled to Finland after the revolution. Between 1928 and 1935 hydrographer in the Bas-Congo. After his second retirement, in 1964, returned to Boma, as advisor to the Congolese RVM. 13

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managed to singlehandedly put the department back on its feet. By 1956 he had improved the regular gauging of floods and tides on the river and streamlined the inherited overlapping triangulation networks. He introduced the first regular streamflow measurements in the various arms of the river. Under his guidance the cartographic coverage of the maritime river was finally completed, including the location of all submerged rocky outcrops on the riverbed between Boma and Matadi. This work resulted in a new, this time illuminated, buoyage system, allowing nighttime navigation. Under his watch 50 different hydrographic charts and 20 tables & graphics were kept up to date on an ongoing basis. While at the end of the Second World War the fairway depth had been 8 m [26 ft], in 1953 dredging had raised that figure to 9.15 m [30 ft] (Fig. 20.7). In 1950 Khokhloff and his team witnessed the arrival of the first echosounders. This equipment allowed for hydrographic surveys to be accomplished far faster and in continuous lines instead of individual points. The movement of shoals throughout the braided section could now be followed more closely, thus limiting dredging operations to the critical passes. Ergo the fairway clearance could be maintained more economically. Another improvement was made in 1954 when buoys were equipped with lights and horns and adorned with reflective sheeting (Scotch lite). Between 1951 and 1960 the navigability of the braided section diminished again. The opening up of the Nisot Pass, combined with the hard points in the river and the changes in the Mateba U/S Pass had pushed the Camoëns Pool meander to the west (seaward) until the Papyrus Island head forced the flow to split. Sediment started to accumulate on the downstream side of Birds Island resulting in decreased flow through the pool and consequently the pass started to silt up. At the same time a channel opened to the south of Papyrus Island, joining the flows along the Angolan shore. While between 1951 and 1955 navigational depth

Fig. 20.7 A diagram representing the volume dredged (blue line) and the corresponding navigational depth (red line) in the braided section of the Maritime Congo for the period 1944 to 1962. (After Khokhloff, 1964)

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could be maintained with relatively limited dredging, in 1953 two new dredgers16 had been acquired and modern hydrographic tools, like the first echosounders, allowed the technicians to make more precise bathymetric measurements at a much-improved rate. The arrival of this modern technology made it more economical to maintain a minimum depth of 9.15 m [30 ft]. But then, from 1956 on, the situation started to deteriorate again. The Nisot/Mayaudon Pass became constricted due to a large sandbank developing along Birds Island, across from Ducks Island. However, with the arrival of an extra dredger17 dredging volumes remained manageable (5 mill. m3 [6,539,000 yd3] in 1959) (Fig. 20.8). In 1954 the secondary navigation channel, Mateba Pass U/S, was skirting Birds Island and then swinging north again to reach Mateba Village. Birds Island itself had been growing with extensive mudflats on its downstream side, as was the Turtles Archipelago. By 1959, the year before the independence of the country, the morphology was even worse.

Fig. 20.8 The situation in 1954. The Nisot Pass is narrowing as is the fairway through the Camoëns Pool. Here vessels are now forced to follow a S-pattern to clear the shallows. Notice also that, after many years, the coordinate system centered on the Cul de Boma hill has been replaced by the new, national Congolese coordinate system (For those that are interested, the new coordinates of the Cul de Boma Benchmark (0,0) were now 381.980,99 in x and 350.353,59 in y)

16 Dredger Matadi and Mateba, built in 1950 by L. Smit & Zn in The Netherlands. Each 67.5 m long with a hopper capacity of 840 m3. 17 Maxwell, built by Gusto Wharf in The Netherlands, in 1959, with a hopper volume of 800 m3.

20.3

Alexandr Khokhloff Returns

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Fig. 20.9 By 1959 the Camoëns Pool was losing significant flow to the southern Portuguese passes, thereby compromising the Camoëns crossover. Similarly, the Mateba Upstream Pass was losing flow as a new channel was building closer to the Turtles, a new Fishermans Pass?

The northwestern mudflats of Birds Island had grown into an archipelago, called Flamingos and the ones on the south side were called Tumbimbi. Therefore, the Camoëns Pass had been pushed further west, creating a tortuous navigation path and a sharp bend in front of the Mateba Island. The meandering fairway above Birds Island had undergone a similar evolution, its amplitude having grown, made maneuvering to stay within the channel more difficult (Fig. 20.9).

Chapter 21

Independence in 1960

Abstract Unfortunately, in the early 1960s the nautical situation worsened. On the one hand, the river saw exceptionally high floods and sedimentation in 1961 and 1962, while on the other hand, the dredging operations fell back. Congolese authorities requested Belgian assistance and expertise to study and rectify the situation. Various long-term programs were set up for a collaboration between Belgian and Congolese experts. Some of the results were the construction of a scale model in the laboratory in Belgium, abandonment of the “classic” fairway for a new channel, and the acquisition of four new and larger dredgers. While in the 1970s the navigational situation started to improve and in 1986 a new, electronic navigation network was installed, in the 1990s a new and dangerous behavior of the fairway emerged. Luckily, the engineering community had learned that you cannot “tame” a river, but that mankind has to work “with” it. Keywords Zaïre · Scale Model · Riffle formation · Kasai dredger · Mandeifu Rock · Syledis · Kudi Boma Between 1961 and 1970, after the independence of the country, two factors contributed to a decline of the available depth in the fairway: 1. Exceptionally high floods1 in 1961 and 1962, brought unusually large amounts of sediment. 2. A reduction in yield in the actual dredging operations. The 1960s would see numerous changes in the river’s behavior. Due to persistent sedimentation of the Nisot Pass it was eventually decided (in 1966) to abandon the Nisot-Mayaudon-Camoëns route and concentrate on the northerly fairway through the Mateba Upstream Pass. In 1968, the Congolese authorities requested Belgian

1 Khokhloff in December 1961 recorded a discharge of no less than 80,000 m3/s in Kinshasa [2,822,000 cfs], whereas the average is 40,000 m3/s [1,412,600 cfs]. The maximum until then observed had been 63,000 m3/s [2,224,800 cfs]. The water level had reached 6.26 m at the end of 1961 and 5.84 m a year later, while in the 60 preceding years the water level had never surpassed the 5.25 m mark.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Van Pul, Hydrography and Navigation on the Congo River, https://doi.org/10.1007/978-3-031-41065-9_21

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expertise to assist the Congolese RVM (Régie des Voies Maritimes) in remedying the situation. One of the decisions was to study the situation in detail by the construction of a scale model at the then Hydraulics Research Laboratory in Borgerhout-Antwerp. For the immediate improvement of the navigational evolution, and with USAID funds, a powerful cutter suction dredger2 was brought in that eventually dredged the crossover in front of the islets two and three of the Turtles Archipelago and also downstream in front of the Mateba Village. We are all familiar with meander-forming in rivers. Their evolution can be disturbed by many fluctuating factors, for instance varying sediment transport and discharge, different flow speeds (including spiral movements) throughout the water column, geology (sand, clay, rock), and others. When the river enters a wide, flat area with a shallow gradient, all these factors combine to create a complex morphology and flow behavior. In a sense the river becomes “alive” (Fig. 21.1).3 In June 1966 President Mobutu had launched a “Campaign of Authenticity” by abandoning, among many others, the colonial name of the capital Leopoldville for its original name of Kinshasa and subsequently, in October 1971 the “Republic of the Congo” became the “Republic of Zaïre.” In the following years, the nomenclature on the navigation charts began changing as well. Following the early 1960s high runoffs the once-thought stable shoreline in the braided section had been extensively modified by nature and a fairway of 9.10 m

Fig. 21.1 By 1966 Fishermans Deep had morphed into the wider and deeper Mateba U/S Pass but two crossovers still existed further downstream. The Camoëns Pass, not ten meters [33 ft] deep anymore, had moved further west again, thereby flattening out but also narrowing to, in places, barely a hundred meters [330 ft] wide

2

A cutter suction dredger is equipped with a rotating cutterhead that is lowered to the riverbed on a suction boom. The dredger is kept in position by means of spuds and anchor wires during the dredging operation. The head sweeps left and right, clearing a path at the required depth. 3 Eminent hydraulic engineer Jean-Jacques Peters, for many years an expert on the Congo River, would say: “The river is a patient, you have to listen to it.”

21.1

The Scale Model

173

[30 ft] became increasingly difficult to maintain. The fact that a lot of experienced personnel had suddenly left the service upon the independence of the country and the outdated dredging equipment available did not help the overall situation. By 1967 available depth had been reduced back to 7.60 m. Between Boma and Malela, where the river spreads out, sandy crossovers move such that a definite natural thalweg is never formed, and navigable channels are reduced to 5–6 m [16.4–19.7 ft] in depth. Since the beginning of the twentieth century, dredging had been the sole means to maintain fairway depths and assure access to the Congolese river ports for ocean-going craft. While before 1900 the navigable depth was 4.25 m [14 ft], by 1908 it was 6.10 m [20 ft] and 6.70 m [22 ft] in 1925. In 1934 minimum depth had reached 7.30 m [24 ft]. By the end of the Second World War, it was 8.50 m [28 ft] and in 1953 the minimum depth was kept at 9.10 m [30 ft]. The unusual floods of 1961, 1962, and 1963 and other aggravating circumstances degraded the fairway with the result that minimum depth in the late 1960s was again below 7.50 m [24.6 ft]. From 1967 to 1986, numerous studies were carried out by former engineers and hydrographers of the Colonial Waterways Department and their Congolese successors, in the field and in the hydraulic research laboratories in Belgium, regarding the navigability of the Maritime Congo River, in particular the braided section. The aim was to transfer hydraulic knowledge and technology to the Congolese RVM that, at the time, still lacked its own Hydraulic Research Department. The Antwerp lab had already, between 1958 and 1962, conducted studies on scale models of the Inga Run-of-River hydroelectric site in the cataract region, upstream of Matadi. Now the plan was to build two models, one from upstream Princes Island to Birds Island to study the sediment supply process and one from Fetish Rock to Ziamanganga, the alluvium deposit area. This last one could then eventually be extended to the Grass Archipelago. In the end though only one scale model was constructed.

21.1

The Scale Model

While for over 30 years the traditional fairway through the Fetish Rock and Camoëns pools had been used, in the 1960s a new passage had slowly emerged, by natural evolution, through the Mateba Upstream Pool (Fig. 21.2). Due to a lack of up-to-date dredging equipment,4 the Congolese Waterways Department had been unable to keep the traditional Nisot/Mayaudon Pass fairway open and at the same time dredge the Mateba crossover, it had hesitated to tackle this new evolution. In March 1967, the SVN finally started dredging in the Mateba U/S pool expecting to be aided by the early, but unfortunately minor, spring flood season. Thus, the many difficulties encountered continued, until at least the late and major

4

Three dredgers with an 800 m3 capacity, one of which was the Mwene-Ditu.

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Fig. 21.2 A map of the actual scale model (red outline) at 1:500, built in the then Hydraulics Research Laboratory in Antwerp. It measured 48 m [157 ft] long by 16 m [52.5 ft] wide. In the real world, this covered over 120 km2. By foregoing the Fetish Rock Pool, it suggests that the Congolese authorities were looking for a purely “domestic” solution to the navigational issues on the breaded section of river

flood season in September 1967. In both passes, the depth would continue to hover between 7.30 and 7.60 m. The main advantage of opening the Mateba U/S Pass fairway was that the amounts of regular dredging would be far less than what was necessary to maintain the traditional fairway through the Fetish Rock and Camoëns pools. To reinforce the dredging fleet, it was expected that two new trailing suction hopper dredgers5 with a capacity of 1300 m3, would arrive at the beginning of 1969. Experience had indicated that with further deepening of the existing fairway through the Fetish Rock Pool, the dredging costs had escalated disproportionally. Up to then dredging operations had been planned by studying previous sounding charts and anticipating future developments. So, to improve the fairway without excessively increasing the budget, it was deemed more advantageous to construct a scale model where interventions in the river morphology could be simulated and the resulting bed evolutions observed in an accelerated fashion. Construction of the model was planned for 1968 with tests to be done in 1969 and 1970 (Fig. 21.3). In 1969, due to the solid clay shore between the Mateba Village and Ziamanganga the migration of the downstream pass had been blocked. The result was that the Nguvu Pass (formerly, Hippos) opened with a chain reaction further downstream. In 1970 another geologic control point upstream started to manifest itself, again

5 The new dredgers were the Mayumbe and Banana, arriving in 1970. Six years later they were joined by the 1500 m3 capacity Tshuapa and Kasai.

21.1

The Scale Model

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Fig. 21.3 The navigational channel between 1969 and 1971. The Turtles Archipelago had moved downstream, making way for the Mateba Upstream Pass. The Ziamanganga (Convensaingh) Crossover was closing to the benefit of the Mateba Downstream Pass along Katala Island

showing the influence of the geological situation on the morphological behavior of the river. Studies initiated on the scale model, based on over 30 years of hydrographic measurements, were intense. Bathymetric measurements, streamflow, discharge, water levels, scour and suspended materials, geology . . . all these factors were reviewed. Studies disclosed that the hard points in the divagante region—locations that were under geological control6—played a significant role in the evolution of the river morphology. The studies focused primarily on the evolution of depths between five and eight meters [16 & 26 ft] in areas that were judged to be “dredge able.” Among many other revelations, it was observed that sandbanks had the tendency to move from one side of the thalweg to the opposite side. Going back to historical data, this phenomenon had happened between 1943 and 1949 when the Diambote Bank, north of the Grass islands, had crossed over and downstream to the Lawrence islands, in front of Malela (Fig. 21.4). An advantage of the use of the echosounder was that the longitudinal fairway profile could now be studied: the survey vessel would travel the length of the thalweg and record in real time the navigable riverbed and its undulations. Another fact that surfaced was that a pass silting up could be detected when on the upstream side the water level would start to rise. But that required a sufficient network of accurately calibrated gauges distributed along the various channels. When a change in water level occurred it was a matter of finding out where the new thalweg was being formed and start dredging at the new location to assist and speed up the natural transformation, instead of continuing the effort, against nature and at ever-increasing expenditure, in a pass that was doomed anyway. The goal

6

Geological control: even small areas of clay influence the natural “creep” of passes.

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Fig. 21.4 The formation of a riffle can be detected by a subtle change in the water level between two gauges

would be to work with nature rather than impose a less flexible and ultimately more costly “man-made solution.” On top of that it was a matter to follow and compare the change in flow distribution through the various passes. The example being the Puasi Pass along Mateba D/S, which started to develop from 1965 on, but could only be opened for commercial traffic in 1970.

21.2 Nineteen Seventies, Ups and Downs In the early 1970s the situation in general improved: more normal flood stages, better hydrographic surveillance of the braided section—this with the support of the then Belgian Hydraulics Research Laboratories—plus two new dredgers7 and the resurrection of the RVM with the aid of the World Bank. The new fairway had a harmonious form, skirting various geologic hard points but nevertheless not bothering the natural meander evolution such that the mid-1970s provided the best

7

Kasai and Thuapa. Built 1976 at A. Vuyk & Zn and de Klop (Netherlands). Length 82.81 m, width 14 m, hopper volume 1500 m3.

21.2

Nineteen Seventies, Ups and Downs

177

Fig. 21.5 Due to a lack of enough oversight, in 1977 four shallow crossovers started to develop: south of the “barrage”, east of Tshiongo, the Tshiongo archipelago and south of the Mateba Village

natural navigation conditions that had been experienced since the end of the 1950s (Fig. 21.5). The year 1971 saw two scientific missions from Belgian hydraulics engineers conducting data collection in the divagante region, while at the same time in Antwerp the base for the scale model was constructed in the hall of the institute. With the new echo sounding equipment, in 1971 it had been found that between the upstream head of Birds Island and Mateba Island, a major rocky outcrop called Mandeifu Rock8 existed that was normally buried under the silt, but at flood seasons, the rock bottom could get exposed to the waterflow. It was an “up-to-then” hidden hard point, and it did explain why, in the past, the Mateba U/S Pass had, at times, behaved so erratically and why the Turtles and Flamingos archipelagoes and their associated shoals never evolved. In December 1977, a sudden degradation occurred in the fairway with the result that the available depth in the passes fell to 5.50 m [18 ft]. Unfortunately, regular soundings of the fairway had lagged so the authorities responsible were taken by surprise. The precarious situation could not be solved with the three dredgers of the RVM (Banana, Mayumbe, and Kasai) available at the time (Fig. 21.6). More scientific missions from Belgian hydraulics engineers to the divagante region9 would follow. In the mid-1980s flood discharges were relatively weak and water levels remained quite low, with the result that the fairway remained stable, and no new secondary channels developed. Intensive dredging in the Birds North Pass allowed the navigable depth to improve from 7.85 m [25.8 ft] in 1983 to 8.23 [27 ft]

8 In honor of Jean-Jacques Peters, who for many years had devoted his career on improving the divagante region, the rock was named Mandeifu, meaning “The Bearded One.” 9 At the time the Congo River was known as Zaïre River.

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Fig. 21.6 The Kasai dredger, fully loaded with sand, ready to onload. (J-J Peters Archive, Flanders Hydraulics, Antwerp)

in 1984 and even 8.84 m [29 ft] in 1985. Another development, this time electronic, took place as well: In 1986 measurements were made at the topographical level to prepare for the installation of three “Syledis”10 radio beacons, a forerunner of GPS, at the Muba Hill (NE of Boma), Seke dia Mbungu (near Kanga) and Kaitshianga. With the submerged Mandeifu Rock formation again exposed to the river in the early 1980s the Mateba U/S Pass became unstable again as a lot of the discharge through the pass was lost though several by-channels. Three important side channels were identified: Birds-South, Central U/S, and Central D/S. Engineers feared that the Mateba U/S route was on the verge of collapsing. An alternative fairway through the upstream shoals was discounted, as other hard points might be discovered and returning to the Kindu (Nisot) Pass through the Fetish Rock Pool was out of the question as dredging costs would be excessive. It was decided to monitor the natural evolution closely and concentrate on targeted dredging in the existing fairway along Mateba Island, thereby avoiding the submerged Mandeifu Rock outcrop (Fig. 21.7).

10 Syledis: SYstème LÉger pour mesurer la DIStance. French radio navigation system from the 1980s and 1990s.

21.3

About Dredging

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Fig. 21.7 The Mandeifu Rock had in fact been discovered in 1932, but its importance in shaping the river flow was not understood at the time

21.3

About Dredging

To improve navigation on alluvial rivers, one can, on the one hand, construct permanent structures like overflow levees, cribs, groynes, and the like, but on some rivers, especially very wide ones with a high or unpredictable discharge, like the Congo River, those “hard” methods will have only a minor effect or even none. Moreover, the risk exists that such hard structures in a morphological dynamic river system will even have an adverse effect in the long term, since they are designed for a certain morphology which is inevitably changing over time. The alternative option is the use of “soft” engineering. This is based on the longterm knowledge and subsequent understanding of the various mechanism that affect the river’s behavior, which is mainly an interaction between morphology and hydrodynamics. Every river, with or without permanent improvement structures, at some time will need dredging to maintain the navigation channel at the desired depth. With the hard method it is aimed to reduce dredging expenditures by building durable constructions in or along the river. As mentioned before, the question is how effective such hard constructions will be overall if the river system in question is highly morphodynamic.11 When using the soft method, engineers will, as best as they can, anticipate future natural behavior of the river and only intervene, to accelerate natural evolutions, by

11

Morphodynamic: Characterized by vigorous and changing form.

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Fig. 21.8 Detail of the contorted configuration of the Mateba Upstream Pass in 1987. It would require the deployment of a cutter suction dredger to rectify this situation

means of selected dredging. The braided section of the Maritime Congo River, due to its large discharge, and at times high flow velocities12 is economically unsuited for the construction of permanent structural improvements. As a result, targeted dredging in function of the natural evolution of the river’s morphology is the most appropriate way to maintain and improve the fairway to the DRC riverports. It will be clear that good and regular monitoring of the river’s behavior (like surveying, flow measurements, and the like) is essential for the soft method (Fig. 21.8). Rivers are extremely powerful phenomena and dredging in areas that nature has decided to be filled in due to changes in morphology is a hopeless task. For successful river management it is a matter of working with the river, instead of against it. Until the second half of the twentieth century, most hydraulic engineers believed rivers needed to be “tamed.” That might be possible, at great cost in smaller rivers with limited to no morphodynamic conduct, but in large ones this approach is economically unfeasible. We witnessed this in the damming of the Mateba Deceiving Bend in the 1930s. On the contrary, targeted dredging along the fairway aids the natural morphological evolution. Such an approach avoids uneconomical dredging. By the end of the 1970s, employing this last method was believed to be the most appropriate approach for the Maritime Congo River (Fig. 21.9). At the start of 1988, the navigational situation suddenly became critical. The turbulence in the Mateba U/S Pass, due to the Mandeifu Rock, coupled with

12

Velocities up to 8 km/h [7.2 ft/s] over a width of up to 20 km [12 mi].

21.3

About Dredging

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Fig. 21.9 In 1988 and 1989 a large cutter suction dredger was hired to remove harder layers of bed material in three specific locations. Meanwhile, the CVM trailing suction dredgers continued with maintenance dredging tasks

substantial amounts of sediment deposits along the Mateba Grand Island, threatened to cut-off deep-water navigation to Boma and Matadi, without any alternative solution immediately available. As several meters of sand needed to be removed in the critical crossovers it was decided to bring in a stationary cutter suction dredger from outside sources to remove the accumulations. This was deemed the only solution to save the existing fairway in the shortest time possible. Besides, it would restore the natural cleansing system by the river. The dredged material would be dumped in the by-channels, to limit them draining essential discharge away from the main channel. It was hoped for that the by-channels would show a tendency of sedimentation due to the decrease in discharge. An analysis of the history of the fairway development indicated that in the past decades no thalweg had ever evolved in the dump area. The year before a seismic-geotechnical survey had indicated that more hard features—rock and clay layers—lurked under water. The use of a cutter suction dredger was therefore deemed essential to remove some of those undesired hard spots. In the fall of 1988 and again in 1989, the dredging program was accomplished, and it proved to be a success. After this emergency intervention, the Mateba passes, both upstream and downstream, remained stable for several years. The fairway meanders showed a slight curvature, connected by straight sections. Nevertheless, by 1996 the D/S end of the Ntua Nkulu Deep (West Deep) showed a tendency to split again, with one arm reaching back into the Fetish Rock Pool, an evolution which was akin to the situation in 1918 when hydrographer Nisot had proposed to connect the then called West Deep with the Congo Yella Deep (Fig. 21.10).

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Fig. 21.10 By 1996 the morphological evolution was again in question. See the “Ezaty” beacon (in red) for reference with the previous chart

Chapter 22

Based on Detailed Land Surveys

Abstract All the hydrographic work on the river had been based upon decades of improving the land surveys, the leveling operations, and the cartographic enhancements brought about by modern technologies. Here we look at some of these developments. Regular natural changes in the powerful nautical environment forced the colonial administration and later the Congolese authorities to review and constantly re-establish the network of beacons and benchmarks throughout the maritime region to be able to continue and improve the bathymetric surveys. Keywords Triangulation · Leveling · Bathymetry · Instruments We have seen that for decades the bathymetric measurements were based on a local survey network. Before 1932 the local topographical grid had its origin at the “Geo Creek” on the Angolese shore. It was derived from the original western (Oeste in Portuguese) bench mark “Base O” of the Portuguese Baseline in the Congo Yella Plain. From 1932 until 1958 the origin of the local grid moved to the Belgian bench mark “A”, this time on the hill at Kudi Boma (Cul de Boma) and finally it became a theoretical reference point, originating at 14° E (being x = 500,000 m) and the Equator (y = 10,000,000 m) (Fig. 22.1).1 The basis, or datum, for the leveling by the SVN,2 on the other hand, was the 0.85 m mark on the tidal gauge in Banana, or the average sea level at this point, an arbitrarily agreed level. All elevation bench marks in the country would refer to this point. From a practical standpoint, the bench mark used at Banana was at +1.31 m. As an example, bench mark SVN-1953-BO/001, a bronze bushing on the base of the signals mast on the waterfront in Boma, had an elevation of 5.904 m. Bench mark R/145, on km 45.4 along the highway to Banana, where SETAC3 attached its leveling network in 1957, was at an elevation of 126.427 m.

1 These rectangular grids were calculated, considering the geographical coordinates, magnetic north and the gauss projection conform F.14. 2 SVN: Service des Voies Navigables. 3 SETAC: French topographical company.

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Fig. 22.1 Accurately measuring water levels required a dense network of leveling bench marks throughout the region. The first detailed, national leveling grid was set out along the highway from Boma to Banana and Moanda in 1957 (the black, dash-dotted line along the north). At the same time a local network of bench marks was developed, augmented in 1959, 1970, and 1971. In 1985–86 three “Syledis” radio stations were installed for radio navigation

Modern leveling was done with WILD N2 and WILD N3 instruments, with the latter, being twice as precise as the former, for long distance work (across wide channels). The regular (short) distance covered between leveling rods (with the instrument in the middle) was maximum 120 m. (WILD N2). As some bench marks were washed away over the years and others did seem to have sunk, risen, or simply had elevations that seemed suspicious over time, renewed leveling work was done over the years, following strict procedures and accompanied by complex calculations (Fig. 22.2). The same criteria were adopted for the fieldwork of the triangulation network along the Maritime Congo and the subsequent calculation of the coordinates of each bench mark. Since the original baselines of the 1930s of (then Portuguese) Congo Yella and Kinshasa-Ndolo were at some point abandoned in favor of new—and even more accurately measured—baselines at Kitona (near Moanda), Matadi, and Kinshasa, the calculated coordinates of already known and still existing bench marks saw new geographical and rectangular figures. Between 1968 and 1971 more work was done, this time by the SVN and in cooperation with various Belgian Hydrographic Missions. Between 1973 and 1975 a British company (Hunting Surveys) was hired by, what was then called Zaïre, to do a comprehensive topographical control survey of the entire river estuary.

22

Based on Detailed Land Surveys

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Fig. 22.2 The original Belgian coordinate system in the Lower-Congo was calculated from the Portuguese baseline in the CongoYella Plain. Later a second baseline was created on DRC territory near Banana (Kitona). The Muba point near Boma eventually became the center for the electronic navigation system employed on the Maritime Congo River

Fig. 22.3 A hydrographer on a leveling job in the divagante region in the 1950s or 60s. He is using a Wild N3 Level, the most precise leveling instrument at the time. (J-J Peters Archive, Flanders Hydraulics, Antwerp)

Needless to say, that today this kind of labor-intensive and slow survey process has been superseded by gps technology (Fig. 22.3).4 4

An overview of the triangulation work in the Congo basin can be found in Meex P. (1997) “Historique du réseau triangulé au Congo belge/Zaïre”. Brussels. Bull. Séanc. Acad. R. Sci. OutreMer. 23 p.

Chapter 23

Epilogue: A Concept for the Future?

Abstract While the port of Matadi is the gateway for the DRC to trade with the world, its topography does not allow for major expansion in the future. While engineers in the past recognized these limitations, a new location for a modern DRC port has, up to now, not been explored in detail. In this epilogue, the author develops a concept for a twenty-first century container port in an appropriate location with relatively minimal cost for an efficient connection with Matadi and the rest of the country. Keywords Container Port · Luango Channel · Monolith · Mbungi Island In 1887 the decision was made to build a railway from Matadi—then an uninhabited, rugged hillside on the south bank of the Maritime Congo River—to Kinshasa on the Haut-Congo, to circumvent the cataract region. Three years later a single, 35 m [115 ft] long pier had been built at Matadi. When in 1892 the railway company did a comprehensive bathymetric survey of the anchorage it was proposed to lengthen the pier by 44 m [144 ft] to allow larger steamers to dock. By 1967 the port had reached its current layout with a quay length1 of 1600 m [5249 ft]. Furthermore, downstream from Hell’s Cauldron is a small container terminal with a berth length of 330 m. Due to the hills reaching to the waterline, the container yard is extremely narrow, with containers parked up to a maximum of only 180 m [590 ft] from the water’s edge. Unloading fuel products is done at two other jetties2 a few 100 m downstream. Today, port enlargement in the Matadi area is impossible. In the long term the DRC will have to consider the establishment of a new port area, in a location where ample space will be available for future expansion (Fig. 23.1). A major impediment for the DRC government is, on the one hand, the local topography in the Matadi region, and on the other hand the proximity of Angolan territory, 6 km downstream. From there on, the DRC has no authority over the lands along the left bank (south side) of the river. Any new development will have to be

1 2

Matadi wharf 625 m. Fuca Fuca section: 425 m, Kala Kala (inaugurated in 1967) 560 m. Oil port at Ango-Ango.

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Fig. 23.1 The all-metal pier in Matadi in 1932. It had started as one jetty with, by 1907, a second jetty, both interconnected. Shortly after the entire construction would be reinforced with a concrete quay. Before the Second World War a second quay (Fuca-Fuca) would be inaugurated, followed by a third (Kala-Kala). Here we see a “Ville”-boat and the government cutter “Kinshasa.” Due to a lack of heavy-lift quayside cranes, ships had to use their on-board tackle for loading and unloading. (Devroey Family Archive)

found on the northern or right bank of the river. Unfortunately, between Matadi and Boma, the Crystal Mountains prohibit the installation of any large port facilities. Nevertheless, since Matadi is currently the main oceanic connection of this great Central African country, a way will have to be found to enlarge the DRC’s sea trading facilities to cope with the inevitable growth of its international import and export. With climate change, the issue has even taken on a greater urgency. From a geographical point of view, it is only from the city of Boma on that a potential site might be found. Of course, it is not only (flat) topography that determines the location of a new port. Numerous other factors come into play to create a successful shipping hub. But first a bit of history. Prof. Pierre Van Deuren already in 1928 argued for the development of port installations along the lower maritime river. His proposal suggested the development of Katala Island at the downstream end of the divagante region. He, however, overlooked one major impediment: the absence of any major urban center in the vicinity that could anchor a developing port, which would be especially important during the early years. His project, published in a 280-p. book, never got any traction, mainly because it was too complex and ambitious.3 With the further

3

Van Deuren included a futuristic plan to transform the cataract reach of the Congo River into a navigable waterway by means of tunnels, locks, and dams, financially an unachievable goal.

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189

development of Matadi as the main Congolese port, Van Deuren’s idea faded into history. Then, during the inter-war period, a seemingly unrelated idea developed, in 1951 put forward by colonial engineers Devroey and Vanderlinden. They suggested, to circumvent the volatile braided section to, at some point, develop the Luango Channel into a full-fledged navigation channel to be utilized by vessels to reach Matadi. Since Matadi at the time did fulfill all the needs for nautical cargohandling of the colony, they did not go as far as to recommend an alternative harbor location. Since the Luango Channel is entirely within DRC territory, it is indeed an attractive option as opposed to keeping a fluctuating and often unpredictable fairway open through the divagante region as we have seen in this book. Devroey and Vanderlinden could never have envisioned the development of the size of twenty-first century vessels and the navigational constraints, especially due to draught and length, which would severely limit the access of these vessels to the port of Matadi. In 1962, quay-side draught at Kala-Kala was 10 m, less at Fuka-Fuka. Any expansion of the port facilities could only come by moving downstream, as has happened at Petrocongo and Ango-Ango where 16 or more meters are available. But there also, the mountainous terrain that stretches to the waterline prevents major expansion inland. For any further development of port facilities for the DRC, Matadi and area have hit their limits. Commercial sea trade today is dominated by container traffic and that has been the prime driver to propose the concept described below. One of the first container ships in the world was the 1960s Santa Eliana. With 154 m long and 23 m wide it could carry 476 containers. By the 1980s we saw ships like the Dart Atlantic, 220 m long, 30.6 m wide that could carry 4500 TEU4 while today large container ships are 400 m long, 61.5 m wide, and can carry over 24,000 TEU. This has been an evolution that neither Matadi nor Boma can accommodate. It appears that a combination of Van Deuren’s idea of Katala Island and Devroey’s & Vanderlinden’s suggestion of the use of the Luango Channel could prove to be a financially achievable and economically viable expansion of the DRC’s port facilities. While Katala Island is situated too far from any urban center,5 upstream the Luango Channel and just west of the Monolith near Boma, a large enough, flat terrain exists that could be developed into a modern container port. Nowadays, a rail connection with the Upper-Congo could be constructed at a reasonable cost by extending the existing railway from Kinshasa to Matadi by 65 km, along the north side of the winding river. See Fig. 15.5 for a detail of the terrain to be covered (Fig. 23.2).

4

TEU: Twenty-foot Equivalent Unit. A modern, unofficial unit to broadly describe the capacity of a vessel. 5 On top of it, from a geological perspective, the soil conditions at Katala Island do not seem to be attractive for large-scale quay development.

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Fig. 23.2 An overflow dam at the Monolith, incorporating two navigation locks, would minimize silt and sediment access to the Luango Channel. A semi-submerged sediment deflection dam would complement the structure

Since the Luango Channel only takes 13% of the total flow (see Fig. 19.5) of the Congo River, the main issue would be to minimize the sediment throughput of the channel to economize the dredging operations in the Luango Channel. While in the past hard engineering solutions in the braided section have proven to be fruitless due to the immense discharge, the Luango Channel can be considered as a separate river, in comparison not twice the size of the Rhine River in Europe. As such, limiting sedimentation could be accomplished by erecting two structures at the upstream end of the channel, south of the Monolith. Here the channel is restricted to a width of 450 m [1476 ft] with on the north side the Monolith hill and in the south the upstream head of the Mateba Grand Island. A control structure in this location would consist of a combined over- and underflow dam with six gates.6 In normal conditions these gates would allow the overflow of river water, thereby preventing any bedload from transiting into the channel. When necessary, these gates could be lifted to allow flushing out heavier sediment that has accumulated over time on the upstream side. Further minimizing the build-up of heavy bedload could be accomplished by installing a submerged “sediment deflection dam” to guide sediment material toward the braided section. To allow smaller ships to proceed further upstream, to Boma and Matadi, two navigation locks would have to be incorporated. A large one for medium-size

6

In comparison, the movable Storm Surge Barrier in the Oosterschelde in The Netherlands is over six times larger than this structure would be.

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Epilogue: A Concept for the Future?

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Fig. 23.3 West of the Monolith, adjacent to the RN1, a modern container terminal would be able to accept the largest vessels currently in service

seagoing vessels and one for smaller ships and barges. To protect the upstream Mateba Island, it might be necessary to incorporate a flood protection levee along the island’s southern shoreline for a certain distance downstream (Fig. 23.3). These measures would make it possible to develop a modern-day container terminal, downstream of the Monolith Narrows, between highway RN1 from Boma to Moanda on the Atlantic coast. The railway extension from Matadi would provide for a secure and fast inland transfer of containers—or other goods—brought in by sea. This leaves the terminal to be connected to the Atlantic Ocean. To accomplish this a dredged canal following the Luango Channel would have to be established. As depicted in the drawings, the canal would be 35 km [21 mi] long, 20 m [65.6 ft] deep, and have a width at the bottom of 160 m [525 ft]. This is comparable to the current Suez Canal dimensions (Fig. 23.4). Having a deep-water seaport away from the coast has its advantages: the river currents are more stable, the tidal range is smaller,7 and the wind is less volatile, facilitating the maneuvering of large vessels and less disruptive for loading and unloading cargo/containers. Moreover, the supply of renewable energy (wind, solar, and geothermal) is less expensive and the availability of nearby human and commercial resources, in this case the cities of Boma and Kuda Boma, would support the project, certainly crucial in the initial stages. The concept described above is evidently only a sketch of a potential development that could turn the DRC Bas-Congo into one of the largest players in the WestAfrican Sea Trade. It will be obvious that this idea would need a massive, combined

7

In this instance it would be practically nil.

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Fig. 23.4 The central part of the Luango Channel, in the vicinity of the Zambi settlement

research effort to determine the feasibility and affordability of such an undertaking. From an environmental point of view, it would liberate the braided region from any commercial traffic and its potential hazards. Instead, the braided section could be designated a world-class Nature Reserve, without sacrificing further economic development of the Central African region (Fig. 23.5).

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Fig. 23.5 Near Katala Island the new fairway would re-enter the Congo River proper, where another sediment diversion dam would direct bedload downstream, away from the fairway and into the deeper Congo Canyon

Appendices

Appendix 1: A Brief History of the “Congolaise des Voies Maritimes” (CVM) The authorities of the Congo Free State, recognizing the major importance of the maritime access to the Congo basin, already on April 26, 1884, even before the official, international recognition of the CFS, instituted a public utility, headquartered in the city of Boma, that would protect, maintain, and improve the maritime access to the country and the navigable inland waterways and called it the “Service Special de l’Hydrographie”.1 In December 1932, under Belgian rule, the service was restructured and renamed “Service des voies navigables” (SVN), Service of Navigable Waterways. For the maritime section, of the Congo, the sub-heading was “Section du Bas-Congo,” until 1952 when it became “Section du bief maritime” [Maritime section] (Fig. A.1). After the independence of the country in 1960, the maintenance of the maritime access to the Congo slowly degraded until in 1971, under the rule of President Mobutu, the government decided to break up the SVN into three separate entities, namely the Administration of Maritime Waterways (RVM), the Administration of Inland Waterways (RVF), and the Administration of Airways (RVA). In the context of this book, only the RVM is important. The RVM, since 2002 called “La Congolaise des Voies Maritimes” (CVM) is a public entity of a technical and commercial nature with the object of: 1. The study of the hydrography and the navigability of the maritime section of the Congo River and the territorial seas of the DRC. 2. Execution of the necessary works, like buoyage and dredging the fairway, to allow oceangoing vessels safe passage up to the port of Matadi.

1

Special Hydrographic Service.

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Fig. A.1 A workboat of the CVM in the company’s floating drydock in Boma. Notice in the background a freighter passing by on its way to Matadi. (Photo Ir. S. Ides)

3. Providing pilotage to vessels using the above regions, the use of which is obligatory. 4. Management of the coastal station (Banana) and the maritime radiocommunications. 5. Collection of the government-imposed navigation fees, such as port dues, pilotage fees, and communication fees. Due to an amendment of the law, in 2008 the agency was transformed into a company with limited liability. Tasks added were the commercialization of public quays and piers and operation of public wharves on a commercial footing. Besides being responsible for maritime fishing, the company is now also responsible, if necessary, for the cleaning and the disinfection of vessels operating in territorial waters. The CVM headquarters are in Boma with two dependencies, one at Matadi, and one in Banana. It also has an office in the capital Kinshasa. In both Matadi and Banana, pilot stations have associated administrative offices. Matadi also houses a communications sub-station. To fulfill its role, the CVM possesses a fleet of vessels, including four TSHD dredgers. The latest acquisition in this category was in December 2020 when the CVM received the “Manzanillo II,” later rechristened “Félix Antoine Tshisekedi Tshilombo.” This middle-aged dredger is a giant compared to the older dredgers in

Appendices

197

Fig. A.2 The Tshuapa dredger is the sister ship of the Kasai. Both vessels were built in 1976 in the Netherlands. (J.-J. Peters Archive, Flanders Hydraulics, Antwerp)

the CVM fleet.2 Built in 1988 in France, it has a hopper capacity of 4000 m3 (Fig. A.2).

Appendix 2: Congo Waterways Interbellum Figures In general, below an altitude of 500 m, the rivers in the cuvette centrale run tranquil. Upstream though, at the higher elevations, rapids and waterfalls create white water conditions where navigation is impossible(Fig. A.3). In colonial times navigable Congolese rivers were classified into three categories: Category 1: River channels with a depth of 2.0 m [6.5 ft] at high water, 1.3 m [4.26 ft] at low water (800-ton and 1200-ton barges3). Category 2: River channels of 1.5 m [4.9 ft] at high water, 1.0 m [3.3 ft] at low water (150- and 350-ton barges, but exceptionally 500-ton barges, when river bends did permit it).

2 3

Banana (1800 m3), Kasai & Tshuapa (both 1500 m3). These tonnages are metric and are only nominal. See below for more details.

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Fig. A.3 An overview of the navigable network in the Congo basin in colonial times. In 1914 the dotted reaches were also classified as navigable, but no further information on them is available. Improving rail and road connections in the 1950s made water transport on the narrower, secondary rivers uneconomical

Category 3: 1.2 m [3.9 ft] in the wet season, 80 cm [2.6 ft] in the dry season (Packet steamers with a 40-ton barge). Category 4: 60 cm [2 ft] in the dry season. Only for motorized whalers.

River reaches according to category (see Fig. 5.1 for details): Lower-Kasai (Kwamouth to Ilebo) High-Kasai (Ilebo – Djoku-Punda) Upper-Kasai (Tshikapa – Makumbi) Fimi: up to Kutu Inzia: up to Mushuni and Bao Kwango: up to Kingushi Kwenge: up to Kwenge

Cat. 1 Cat. 3 Cat. 3 Cat. 2 Cat. 2 Cat. 3 Cat. 3

605 km [376 mi] 184 km [114 mi] 100 km [63 mi] 184 km [114 mi] 38 km [23.6 mi] & Cat 3. for 170 km, [105 mi] 215 km [133 mi] 25 km [15.5 mi] (continued)

Appendices Kwilu: up to Kikwit Lokoro: up to Lokolama Lukenie: up to Kole Lulua: up to Luebo Lutoi: up to Kiri Lutshima: up to Lutshima Mai-Ndombe (Lake): to Donkese Sankuru: up to Pania-Mutombo Wamba: up to Mukila

199 Cat. 2 Cat. 3 Cat. 3 Cat. 3 Cat. 3 Cat. 3 Cat. 2 Cat. 2 Cat. 3

342 km [212 mi] 250 km [155 mi] 792 km [492 mi] 58 km [36 mi] 68 km [42 mi] 15 km [9.3 mi] 127 km [79 mi] 590 km [367 mi] 146 km [90 mi]

Total navigable kilometers in the Kasai watershed in 1939: 3909 km [2429 mi], of which 15% in Cat. 1, 33% in Cat. 2, and 52% in Cat. 3. In the 1920s and 1930s several barges, designed for the Congolese waterways, were built. This is a selection: 1200-ton barge: Type V (1937): 76 m [246 ft] long, draught of 2.35 m [7.7 ft], 1521 tons [1676 ST4] load, 1756 metric tons [1935 ST] all-up weight. 800-ton barge: Type L (1931): 62 m [203 ft] long, draught 2.30 m [7.5 ft], 745-ton [821 ST] load, 893-ton [984 ST] all-up. 500-ton barge: Type II (1923): 47 m [154 ft] long, draught 1.80 m [6 ft], 415-ton [457 ST] load, 505-ton [556 ST] all-up. 350-ton barge: Type C (1924): 46 m [151 ft] long, draught 1.80 m [6 ft], 270-ton [297 ST] load, 330 ton [263 ST] all-up. 40-ton barge: Type VII (1923): 25 m [82 ft] long, draught 0.95 m [3 ft], 45-ton [49 ST] load, 57-ton [62 ST] all-up (Fig. A.4).

Selected Data on the Maritime Congo Average discharge: High flooding period (October–January = 57,670 m3/s or 2,036,600 cfs) Lower water period (February–March = 36,276 m3/s or 1,281,100 cfs) Lower flooding period (April–May = 40,282 m3/s or 1,422,500 cfs) Extremely low water period (June–September = 32,000 m3/s or 1,130,100 cfs) The divergence in water level between low water and flood level reaches 7 m [23 ft] at Matadi, 2.7 m [9 ft] in Boma and only 1.5 m [5 ft] at Katala Island where the water flow is a lot slower than in the upstream passes. From Boma downstream the tides influence the water level. At Banana, the tidal range varies between 0.40 and 1.82 m [1.3 & 6 ft]. At Katala Island, the difference is only 0.53 m [1.7 ft], while at Boma it is barely 10 cm [1/3 ft].

4

ST = US short ton.

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Fig. A.4 A tranquil view of the Congo River with a Délivrance packet boat moored at a post. Between the two world wars these small but economical to run steamers formed the backbone of public river transport on the Upper-Congo. (AP.0.0.11242, collection MRAC Tervuren; photo s.d. Tous droits réservés)

Glossary

Bas-Congo The Congo River between the Atlantic Ocean and the Malebo Pool. As such it includes the cataract region above Matadi. In English, “Lower-Congo.” Cantilever Only supported at one end (here the riverbed), no anchors or any other support type at the extremity. Caravel A small, fast sailing ship developed by the Portuguese in the fifteenth century with the aim to explore the west coast of Africa. Congo Couloir The “Corridor-Congo,” from the Malebo Pool, upstream to Tsumbiri. Crossover The transition from one bend in a river to the next. Due to the slower flow speed in the crossover, the thalweg will tend to be shallowed in this stretch. Deadweight Total load a ship can carry; cargo, stores, fuel, crew, passengers, etc. (Fr.: Port en lourd). The Congo boat Baudouinville, built in 1939 for the CMB, had a deadweight of 7139 metric tons and already a draught of 7.85 m. Deceiving bend or by-channel A (secondary) arm of a river whose morphology is showing large sedimentation due to shifting currents and so is unfit for navigation by large vessels (Fr.: Faux bras). Directed dredging Dredging only the shallow areas of the thalweg where, through continuous bathymetric surveys, there is the expectation that it can be developed and maintained into a viable fairway. Not sticking to a particular route if the evolution of the river morphology indicates the natural development of a new navigation channel. Discharge Rate of flow (volume per time unit) passing a specific cross section of a waterway.5 Can be visualized using a hydrograph. Discharge float method Watching a floating object in the current and measuring the distance it travels over a certain time (not officially accepted). 5 For the uninitiated “River Discharge” is sometimes difficult to comprehend. I suggest checking the website of your local waterways department and consult the stream records for the nearest gauging station. The discharge figures will give you a basis to reference the data you will find in this book.

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Glossary

Fairway The navigation route ships follow when traveling up or down river. Today the word thalweg has fallen in abeyance as often major and continual dredging operations on large rivers have created an artificial thalweg. Subsequently, one talks about the “fairway” or “navigation channel.” Groyne or groin wall A short piece of levee, sticking out of the shoreline at almost right angles. The idea of this structure is to narrow the river, as such increasing the water level for a certain discharge improving conditions for navigation (Fr.: Épi: Du.: Kribbe). Haut-Congo The general term for all the waterways in the Congo Basin, upstream from the cataracts (in other words, from Kinshasa on). Limnimeter An enclosed, sensitive form of water level gauge for not only measuring, but also recording the variation of water levels in lakes and rivers. See also “Marigraph.” Marigraph An instrument, located well above the highest water level, that, through a wire and float, on a continuous basis records tide levels on a rotating paper drum. The paper is replaced at regular intervals. Maritime Congo That part of the Lower-Congo River that is navigable by oceangoing vessels, from the Atlantic Ocean at Banana to Matadi. Middle-Congo The Congo River, from Tsumbiri to the city of Kisangani. Needle dam An overflow dam, consisting of a solid wooden or metal framework against which wooden or metal “needles” are leaning, arranged tight against each other to raise the water level upstream. Plimsoll line The load line painted on a ship’s hull, indicating to what maximum draught the ship can be loaded under different circumstances (e.g., depending on temperature and/or salinity of water). Named after the British politician Samuel Plimsoll. Resection Determining the exact location of a new survey point, by measuring the angles to it from three mapped, coordinated points. In geodetic operations, the observations will be adjusted to compensate for various errors. Stream gauge An instrument to measure the flow discharge in a waterway. Thalweg The line connecting the deepest points of a river. Thalweg is German for “valley route.” Tide gauge A simple graduated board that, through a precise leveling, is referenced to a local or national leveling datum. The water level can be read from a distance and, as the water level fluctuates throughout the day, the bathymetric survey crew calculates the river depth by comparing each sounding to the water level gauge nearest its position. Traverse A polygon line that starts at a known reference point. Each leg and subsequent angles are measured and calculated. A traverse is “closed” when the line starts and ends at a point of which the coordinates are known. Upper-Congo The Congo River, also called Lualaba, above Kisangani.

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