Congo River

or Zaire River

River, west-central Africa.

Rising in Zambia as the Chambeshi and flowing 2,900 mi (4,700 km) through the Democratic Republic of the Congo to the Atlantic Ocean, it is the second longest river in Africa. It flows through three contrasting regions: the upper Congo, characterized by lakes, waterfalls, and rapids; the middle Congo, with seven cataracts known as Boyoma (Stanley) Falls; and the lower Congo, which divides into two branches forming a vast lake area called the Malebo (Stanley) Pool.

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▪ river, Africa

Introduction

also called  Zaire River,  

 river in west-central Africa. With a length of 2,900 miles (4,700 kilometres), it is the continent's second longest river, after the Nile. It rises in the highlands of northeastern Zambia between Lakes Tanganyika and Nyasa (Malaŵi) as the Chambeshi River at an elevation of 5,760 feet (1,760 metres) above sea level and at a distance of about 430 miles from the Indian Ocean. Its course then takes the form of a giant counterclockwise arc, flowing to the northwest, west, and southwest before draining into the Atlantic Ocean at Banana (Banane), Democratic Republic of the Congo (Kinshasa) (Congo). Its drainage basin, covering an area of 1,335,000 square miles (3,457,000 square kilometres), takes in almost the entire territory of the Congo, as well as most of that of the Republic of the Congo, the Central African Republic, eastern Zambia, and northern Angola and parts of Cameroon and Tanzania.

      With its many tributaries the Congo forms the continent's largest network of navigable waterways. Navigability, however, is limited by an insurmountable obstacle: a series of 32 cataracts over the river's lower course, including the famous Livingstone (Livingstone Falls) (Inga) Falls. These cataracts render the Congo unnavigable between the seaport of Matadi, at the head of the Congo estuary, and Malebo (Malebo Pool) (Stanley) Pool, a lakelike expansion of the river. It was on opposite banks of Malebo Pool—which represents the point of departure of inland navigation—that the capitals of the former states of the French Congo and the Belgian Congo were founded: on the left bank Kinshasa (formerly Léopoldville), now the capital of the Democratic Republic of the Congo, and on the right bank Brazzaville, now the capital of the Republic of the Congo.

      The Amazon (Amazon River) and Congo are the two great rivers of the world that flow out of equatorial zones where heavy rainfall occurs throughout all or almost all of the year. Upstream from Malebo Pool, the Congo basin receives an average of about 60 inches (1,500 millimetres) of rain a year, of which more than one-fourth is discharged into the Atlantic. The drainage basin of the Congo is, however, only about half the size of that of the Amazon; its rate of flow—1,450,000 cubic feet (41,000 cubic metres) per second at its mouth—is considerably less than the Amazon's flow of more than 6,180,000 cubic feet per second.

      While the Chambeshi River, as the remotest source, may form the Congo's original main stream in terms of the river's length, it is another tributary—the Lualaba (Lualaba River), which rises near Musofi in the Katanga (Shaba) region of Congo (Kinshasa)—that carries the greatest quantity of water and thus may be considered as forming the Congo's original main stream in terms of water volume.

      When the river first became known to Europeans at the end of the 15th century, they called it the Zaire, a corruption of a word that is variously given as nzari, nzali, njali, nzaddi, and niadi and that simply means “river” in many African dialects. It was only in the early years of the 18th century that the river was first called the “Rio Congo,” a name taken from the kingdom of Kongo that had been situated on the lower part of the river's course. During the period (1971–97) when the Democratic Republic of the Congo was called Zaire, the government also renamed the river the Zaire. Even during that time, however, the river continued to be known throughout the world as the Congo. To the literary-minded the river is evocative of the famous 1902 short story “Heart of Darkness” by Joseph Conrad. His book conjured up an atmosphere of foreboding, treachery, greed, and exploitation. Today, however, the Congo appears as the key to the economic development of the central African interior.

Physical features

Physiography

      The expression Congo basin refers, strictly speaking, to the hydrographic basin. This is not only vast but is also—with the exception of the sandy plateaus in the southwest—covered with a dense and ramified network of tributaries, subtributaries, and small rivers.

      The Congo basin is the most clearly distinguished of the various geographic depressions situated between the Sahara to the north, the Atlantic Ocean to the south and west, and the region of the East African lakes to the east. In this basin, a fan-shaped web of tributaries flows downward along concentric slopes that range from 900 to 1,500 feet in elevation and that enclose a central depression. The basin itself stretches for more than 1,200 miles from north to south (from the Congo–Lake Chad watershed to the interior plateaus of Angola) and also measures about 1,200 miles from the Atlantic in the west to the Nile-Congo watershed in the east.

      The central part of the Congo basin—often called the cuvette (literally, “saucer,” or “shallow bowl”)—is an immense depression containing Quaternary alluvial deposits that rest on thick sediments of continental origin, consisting principally of sands and sandstones. These underlying sediments form outcrops in valley floors at the eastern edge of the cuvette. The filling of the cuvette, however, began much earlier. Boreholes have revealed that since late Precambrian times (i.e., since at least 570 million years ago) considerable sediment has accumulated, derived from the erosion of formations situated around the periphery of the cuvette. The arrangement of surface relief, thick depositional strata, and substratum in amphitheatre-like fashion around the main Congo channel, which has been uniform across time, is evidence of a persistent tendency to subsidence in this part of the continent. This subsidence is accompanied by uplifting on the edges of the cuvette, principally on its eastern side—which has also been influenced by the formation of the Western Rift Valley.

      From its sources to its mouth, the Congo River system has three contrasting sections—the upper Congo, middle Congo, and lower Congo.

      The upper reaches are characterized by three features—confluences, lakes, and waterfalls or rapids. To begin with, several streams of approximately equal size unite to form the river. In a little more than 60 miles, the upper Lualaba joins the Luvua and then the Lukuga. Each stream for part of its course undergoes at least a lacustrine type of expansion, even when it does not form a lake. Thus, Lake Upemba occurs on the upper Lualaba; Lakes Bangweulu and Mweru (Mweru, Lake) occur on the Chambeshi–Luapula–Luvua system; and finally Lake Tanganyika, which is fed by the Ruzizi (flowing from Lake Kivu) and by the Malagarasi, itself flows into the Lukuga. Rapids occur not only along the headstreams but also several times along the course of the main stream. Navigation thus is possible only along sections of the upper Congo by vessels of low tonnage; even so, these stretches are in danger of being overgrown by aquatic vegetation, particularly water hyacinths.

      Kisangani (formerly Stanleyville)—located just downstream of the Boyoma (Boyoma Falls) (Stanley) Falls, a series of seven cataracts—marks the real beginning, upriver, of the navigable Congo. This central part of the river flows steadily for more than 1,000 miles to within 22 miles of Kinshasa. Its course at first is narrow but soon grows wider, after which many islands occur in midstream. This change in the character of the river corresponds to its entry into its alluvial plain. From that point onward, with the exception of a few rare narrow sections, the Congo divides into several arms, separated by strings of islands. It increases from a width of more than three and a half miles downstream from Isangi (where the Lomami enters the Congo) to a width of from five to seven miles and on occasion—for example, at the mouth of the Mongala—to eight miles. Beyond the natural levees (formed by silt deposits) occurring on either bank, some areas are subjected to extensive flooding that increases the river's bounds still further. (It is not always easy to distinguish such areas from the “rain swamps” in regions lying between rivers.) The middle course of the Congo ends in a narrow section called the Chenal (Channel), or Couloir (Corridor). Between banks no more than half a mile to a mile wide, the riverbed deepens, and the current becomes rapid, flowing through a valley that cuts down several hundreds of yards deep into the soft sandstone bedrock of the Batéké Plateau. Along this central reach the Congo receives its principal tributaries, primarily the Ubangi (Ubangi River) and the Sangha (Sangha River) on the right bank and the Kwa on the left bank. An enormous increase in the average rate of flow results, rising from less than 250,000 cubic feet a second at Kisangani to nearly its maximum flow at Kinshasa.

      Upon leaving the Chenal, the Congo divides into two branches, forming Malebo Pool, a vast lacustrine area about 15 miles by 17 miles, which marks the end of the middle Congo. Immediately downstream occur the first waterfalls of the final section of the river's course. Cataracts and rapids are grouped into two series, separated by a fairly calm central reach, in which the altitude drops from a little less than 900 feet to a few yards above sea level. The Congo's estuary begins at Matadi, downstream from the rapids that close off the interior Congo; 83 miles in length, it forms the border between Angola and Congo (Kinshasa). At first the estuary is narrow (less than half a mile to about a mile and a half in width) with a central channel 65 to 80 feet deep, but it widens downstream of Boma. There, the river, obstructed by islands, divides into several arms, and in some places the depth does not exceed 20 to 25 feet, which makes dredging necessary to allow oceangoing vessels to reach Matadi. Beyond the estuary's mouth, the course of the Congo continues offshore as a deep underwater canyon that extends for a distance of about 125 miles.

Hydrology

      The Congo has a regular flow, which is fed by rains throughout the year. At Kinshasa the flow has for years remained between the high level of 2,310,000 cubic feet per second, recorded during the flood of 1908, and the low level of 756,000 cubic feet per second, recorded in 1905. During the unusual flood of 1962, however, by far the highest for a century, the flow probably exceeded 2,600,000 cubic feet per second.

      At Brazzaville and Kinshasa, the river's regime is characterized by a main maximum at the end of the year and a secondary maximum in May, as well as by a major low level during July and a secondary low level during March and April. In reality, the downstream regime of the Congo represents climatic influence extending over 20° of latitude on both sides of the equator, a distance of some 1,400 miles. Each tributary in its course modifies the level of the main stream. Thus, for example, the low level in July at Malebo Pool results from two factors: a drought that occurs for several months in the southern part of the basin at that time, as well as a delay before the floods of the Ubangi tributary flowing down from the north arrive, which does not happen before August. The Congo basin is so vast that no single meteorologic circumstance is capable of disturbing the slow movement of the waters' rise and fall. The annual fluctuations may alter drastically, however, when floodwaters from different tributaries that normally coincide with each other arrive at different times.

      Lake Tanganyika (Tanganyika, Lake), apart from brief seiches caused by wind drift and sudden changes in atmospheric pressure, may experience considerable variations in its water level from year to year. In 1960, for example, its waters flooded parts of Kalemi, Congo, and Bujumbura, Burundi. A series of particularly rainy years, followed by a blocking of the outlet by floating vegetation, may explain this phenomenon.

Climate

      Typical of the climate in regions through which the Congo flows is that of Yangambi, a town situated on the river's right bank slightly north of the equator and a little downstream of Kisangani. Humidity remains high throughout the year, and annual rainfall amounts to 67 inches and occurs fairly regularly; even in the driest month the rainfall totals more than 3 inches. Temperatures are also uniformly high throughout the year, and there is little diurnal variability. The average temperature at Yangambi is 76° F (24° C).

      From the pluviometric equator (an imaginary east–west line indicating the region of heaviest rainfall), which is situated slightly to the north of the geographic equator, the amount of rainfall decreases regularly in proportion to the latitude. The northernmost points of the basin, situated in the Central African Republic, receive only from eight to 16 inches less during the course of a year than points near the equator; the dry season, however, lasts for four or five months, and there is only one annual rainfall maximum, which occurs in summer. In the far southern part of the basin—at a latitude of 12° S, in the Katanga region—the climate becomes definitely Sudanic in character, with marked dry and wet seasons of approximately equal length and with rainfall of about 49 inches a year.

Plant life

      The equatorial climate that prevails over a significant part of the Congo basin is coextensive with a dense evergreen forest. The Congolese forest spreads out over the central depression, extending continuously from about 4° N to about 5° S; it is interrupted only by clearings, many of which have a natural origin. The forest region is bordered on either side by belts of savanna (grassy parkland). The forest and savanna often meet imperceptibly, blending together in a mosaic pattern; more rarely, strips of forest invade the grassland. Farther away from the equator, and to the extent that the Sudanic features of the climate become evident, the wooded savanna region, with its thin deciduous forest, is progressively reached.

      As it courses through the solid mass of the Congolese forest, the Congo and its tributaries are bordered by discontinuous grassy strips. Meadows of Echinochloa (barnyard grass), papyrus, and Cyperaceae (sedge) occupy abandoned river channels, fringe the banks, or, behind a curtain of forest, blanket the depressions in the centre of the islands; they also spring up on sandbanks, as well as on the downstream ends of islands that are fertilized by the floods. A shrub, Alchornea, frequently marks the transition to the high forest that grows on the levees behind the banks.

Animal life

      The animal life of the Congo basin is identified to a certain extent with that of the equatorial forest, which is sharply distinct from the wildlife of the savannas. Within this equatorial domain, the Congo and its principal tributaries form a separate ecological milieu. The animal population of the great waterways often has fewer affinities with the neighbouring marshes or the forests on dry land than it has with other river systems, whether of the coastal region or the savannas.

      Numerous species of fish live in the waters of the Congo—more than 230 have been identified in the waters of Malebo Pool and in the waters that flow into it alone. The riverine swamps, which often dry up at low water, are inhabited by lungfish, which survive the dry periods buried and encysted in cocoons of mucus. In the wooded marshlands, where the water is the colour of black tea, the black catfish there assume the colour of their environment. The wildlife of the marshes and that of the little parallel streams do not mix with the wildlife of the river itself.

      The waters of the Congo contain various kinds of reptiles, of which crocodiles are the most striking species. Semiaquatic tortoises are also to be found, as are several species of water snakes.

      The forest birdlife constitutes, together with the birdlife of the East African mountains, the most specifically indigenous of that to be found on the African continent. In the Congo region more than 265 species typical of the equatorial forest have been recorded. Occasionally or seasonally, however, nontypical birds may be observed. Seabirds, such as the sea swallow, fly upstream from the ocean. Migratory birds from Europe, including the blongios heron and the Ixobrychus minutus (little bittern), pass through the region. Species with a wide distribution within Africa, such as the Egyptian duck, also have been noted. Ducks, herons, storks, and pelicans, however, are abundantly represented.

      Aquatic mammals are rare, consisting of the hippopotamus, two species of otter, and the manatee (sea cow), which lives entirely in the water. The manatee has been officially identified only on the Sangha tributary but appears to have given rise to some curious legends on the lower Congo, including its association with a creature called Mami Wata (a kind of siren).

The people and the economy

Life of the river peoples

      Three types of environment are found, either juxtaposed or in succession, along the river and its tributaries: the narrower sections, bordered by firm ground; the wider stretches, dotted with islands and accompanied by backwaters; and the zones where flooding occurs or where there are extensive marshes.

 Almost all the river peoples engage in fishing. Along the narrow sections, where rapids often occur, fishing is only of interest to a small number of villages. The Enya (Wagenia) of Boyoma Falls and the Manyanga living downstream from Malebo Pool attach fish traps to stakes or to dams built in the rapids themselves. Fishing of a very different nature, notably by poison, is conducted in the marshy areas, where the population is more extensive than might be imagined. Among these peoples are the “water people”—the Ngombe—who inhabit the Itimbiri-Ngiri and the triangle formed by the Congo and the Ubangi. Other fisherfolk of the marshes dwell in the lagoons and the drowned forests of the region where the confluence of the Congo and the Alima, Likouala, and Sangha occurs.

      Despite unfavourable conditions, all these peoples are also cultivators. They raise dikes, often of monumental size, to plant cassava on the land thus sheltered from flooding. Other crops, such as sweet potatoes, bananas, and yams, are of little importance. Although the Congo basin has the continent's most important timber resources, the timber industry is still largely undeveloped, mainly because the interior is so inaccessible and because the cost of transporting timber to the coast is so high.

      Few modes of existence have undergone such profound changes as a result of contact with the modern world as has that of the river's fisherfolk. The growth of the towns on the banks of Malebo Pool as well as the taste of urban dwellers for river fish have served to stimulate fishing by relating it to a cash economy. It is not just a question of villagers smoking fish that they sell to passing traders. Increasingly numerous fishing crews sail up the Congo, the Ubangi, and the Kasai, well above their confluences, to fish in the shallows.

Transportation

      The Congo is the most important navigational system in Africa. Within the territorial limits of Congo (Kinshasa) alone, there are some 8,700 miles of navigable waterway. Of this total, 650 miles are accessible at all seasons to barges with capacities of between 800 and 1,100 tons, depending upon the height of the water. The amount of goods transported by water—consisting mainly of agricultural produce, wood, minerals, and fuel—is very modest in comparison to the traffic on European rivers (for example, the commercial traffic from the port of Kinshasa does not reach a million tons), but river transport remains essential for communications with regions that are inaccessible by road, especially in the cuvette. The three principal routes, all of which converge on the downstream terminus at Kinshasa on the Malebo Pool, run from Kisangani, from Ilebo (formerly Port-Francqui) on the Kasai, and from Bangui on the Ubangi. River transport, however, falls short of the role it could play in development. It has actually declined since the states of the Congo basin became independent in 1960 because of serious problems with aging equipment, a lack of maintenance of the infrastructure, and the poor functioning of the public waterway agencies. In Congo only the section from Ilebo to Kinshasa is still important, because it constitutes the river link (the other link being a railway between Kinshasa and Matadi) by which part of the copper production of Katanga is conveyed to the coast.

      This network has fostered economic development in inland areas, far from the coast. Varied activities include the production of palm oil on the banks of the Kwilu, centred on the port of Kikwit, and the establishment of plantations of robusta coffee in the Kisangani area.

      Before such developments could be undertaken, however, it was necessary to overcome the barrier to the sea formed by the Congo's lower course. That feat was accomplished in 1898 with the opening of the railway between Matadi and Léopoldville (now Kinshasa) and in 1934 by the completion of the Congo–Ocean rail line on the right bank between Brazzaville and Pointe-Noire.

      While the river system facilitates navigation, it also hinders land transportation. Only a small number of bridges cross the Congo and its tributaries. The Kongolo rail and road bridge over the Lualaba was reconstructed in 1968, and a bridge over the Congo at Matadi was opened in 1983. Numerous projects to improve the situation nevertheless exist, notably a link between Kinshasa and Brazzaville. This project has long been under discussion, although to financial obstacles are added difficulties caused by political dissension. Several times since the two countries gained independence in 1960, such dissensions have interrupted the ferry traffic between the two capitals.

Power

      It has been estimated that the hydroelectric (hydroelectric power) potential of the Congo basin amounts to about one-sixth of the known world resources, but only a fraction of this potential has been harnessed. The single site of Inga, just upriver from Matadi, has a power potential estimated at more than 30,000 megawatts. Two hydroelectric projects, called Inga I and Inga II, have been completed there since the independence of Congo (Kinshasa). Although the combined installed capacity of Inga is only a small fraction of the total potential, it is greater than the present power consumption of Congo. Thus, it will be many years before the Congo region's energy needs equal the potential output of the river.

Study and exploration

      The problem of the origin of the Congo confronted European explorers from the time that the Portuguese navigator Diogo Cão (Cão, Diogo) discovered the river's mouth in 1482, which he believed to be a strait providing access to the realm of the mythical Prester John, a Christian priest-king. It is virtually certain that, well before the Welsh explorer Henry Morton Stanley arrived in 1877, some 17th-century Capuchin missionaries reached the shores of Malebo Pool. This exploit, however, was not followed up, even by the amply supplied Tuckey (Tuckey, James Kingston) expedition, which was sent out by the British admiralty in 1816 but was decimated and had to retrace its footsteps even before it had surmounted the cataracts. Preposterous hypotheses about the river continued to be entertained, connecting, for example, the upper Niger to the Congo or maintaining that the Congo and the Nile both flowed from a single great lake in the heart of Africa.

 Even after the discovery of Lake Tanganyika (see photograph—>) by the British explorers Richard Burton and John Speke (1858), then of the Lualaba (Lualaba River) (1867) and of Lake Bangweulu (1868) by the Scottish explorer David Livingstone (Livingstone, David), uncertainty remained—uncertainty that Stanley was to dissipate in the course of his famous expedition in 1876 and 1877 that took him by water over a period of nine months from the Lualaba to the Congo's mouth. In the interior of the Congo basin, and above all on the right bank, the final blank spaces on the map could not be filled in until about 1890, when the exploration of the upper course of the Ubangi was completed.

Gilles François Sautter Roland Pourtier

Additional Reading

Gilles Sautter, De l'Atlantique au fleuve Congo, 2 vol. (1966), discusses the Congo basin in general as well as the river itself, covering hydrology, climate, vegetation, and fishing. G.A. Boulenger, Les Poissons du bassin du Congo (1901), is a classic work on ecology. Jan Vansina, Introduction à l'ethnographie du Congo (1966), synthesizes available knowledge on the subject, with a section on the relationship between fishing and social organization. André Huybrechts, Les Transports fluviaux au Congo (1965), analyzes the evolution and organization of traffic on the middle course of the Congo and its affluents in the period 1925–63, and his Transports et structures de développement au Congo (1970), studies the role of transportation in the economic transformation of the Congo–Zaire region from 1900 to 1970. Jean-Claude Willame, Zaïre, l'épopée d'Inga (1986), critically analyzes the economic and political implications of the Inga Dam. Roland Pourtier, “Transport et développement au Zaïre,” Afrique contemporaine, 29(153):3–26 (1990), discusses current transportation in Zaire. Henry M. Stanley, Through the Dark Continent, 2 vol. (1878, reissued 1988), and The Congo and the Founding of Its Free State, 2 vol. (1885, reissued 1970), are classic works on African exploration, describing the author's famous descent of the Congo to Malebo (Stanley) Pool and the two upper Congo expeditions. An introduction to the river's history can be found in Peter Forbath, The River Congo (1977).Roland Pourtier

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