Great river of West Africa, for its vastness of basin and course development among the largest on the Earth, and, for its flow rate, inferior only to the Amazon River. The length of its path, starting from the origins of the Ciambesi, considered as its main spring branch, is approximately 4640 km., While its distance as the crow flies from the origins to the mouth is about 2300 km; the area of the drainage basin is estimated to 3,700,000 sq. km, equal to about 1 / 8than that of the whole African continent. The drainage basin is not limited to the orographic basin; but due to the fact that the river also welcomes the Lukuga, an emissary of Lake Tanganyika, it also includes vast regions that orographically would be part of East Africa. The abundance of precipitation that falls throughout the vast basin, located by considerable extension in the equatorial rain zone, and extending north and south in the subtropical zones of the two hemispheres, with alternating periods of rain corresponding to the respective summers, means that, despite having two alternating periods of flood and low water, the flow of the river remains very high in every season, averaging between 60 and 80 million cubic meters. per second. The Congo basin forms in its greatest extent a vast basin, limited by reliefs from 1000 to 1500 m., exceeding 3000 m. in the N. region of Lake Tanganyika. This conformation gives the profile of the river a special course, so that, while the middle section remains flat, the extreme sections upstream and downstream have very pronounced differences in height and give rise to rapids and jumps that prevent navigability.
According to Sportsqna.com, the Ciambesi, for the greater development of its course, is, as we said, considered as the source branch of the Congo. It originates in the region of the highlands interposed between lakes Tanganyika and Niassa, included in Northern Rhodesia, and runs its course with direction from the NE. to SW. until it drains into the vast swampy expanse of Lake Bangueolo (v.): on leaving it it takes the name of Luapula and forming a tight curve with the convexity to the south, then turns directly north, interrupted by the Johnston waterfalls, until it flows into the lake Moero (913 m.). He succeeds with the name of Luvua and, after another 200 km. of development, in Ankoro, receives from the left the Lualaba which, despite the minor course development, due to its greater reach is considered the main trunk of the Congo, hence the name of Lualaba is preserved in the river even after its union with the Luvua. The Lualaba originates from the slopes of Mount Musofi (1550 m.) In the Catanga plateau, from which it collects the sloping waters from the northern slope, about 100 km away. to O. of Elisabethville. Mountain river in its upper stretch for about 400 km. of development, interrupted by frequent and elevated waterfalls, becomes, after its confluence with the Lubudi, its left tributary, in the Bukama region, at about 600 meters above sea level, a river with a navigable level and subject to easy expansions that give rise to lakes more or less persistent. Downstream from Ankoro, the combined Luvua and Lualaba, which retain the name of Lualaba as mentioned, continue in the direction of N. receiving from the right after about 120 km. the Lukuga, emissary of Lake Tanganyika. Then the river narrows up to 500 m., Flowing within the rocky gorges of the Portes d’Enfer, and its navigability remains interrupted. But in Kasongo (Maniema), after the confluence of the Luama, it becomes navigable again by flowing in a flat bed and reaching a full width of 2500 m. After bathing the ancient and well-known Arab market of Nyangwe and passing the Kibomno rapids, the Lualaba crosses the equatorial forest and the district of Kindu and finally, after passing the waterfalls of the same name and descending to an altitude of 500 m., It returns navigable up to Ponthierville (470 m.), For a stretch of over 300 km.
It receives numerous tributaries in this section, especially from the right; among which we remember the Elila, the Ulindi and the Lowa, coming from the mountain regions that close the basins of northern Tanganyika to the W, of Lake Kivu and Lake Edward. Beyond Ponthierville begin the Stanley Falls: a succession of rapids and jumps of limited height (3 m.), Which for about 100 km. interrupt the navigability of the river. But this resumes free and safe beyond Stanleyville, when the river, which by now takes the name of Congo, proceeds slow and rich in water, dividing itself into numerous branches that enclose vast river islands, populated and covered with thick wooded vegetation, as well as a dense forest is covered throughout the region that the river crosses. It is in this section that the river cuts through the vast basin which once constituted an immense closed basin, changing direction and forming that characteristic curve which reaches with its northern convexity the latitude N. of 2 ° 15 ‘, to then fold, with an almost constant trend, towards SW. Numerous and powerful tributaries bring it rich tribute of waters on both sides. We recall the main ones: from the right the Lindi and the Aruwimi, which with the name of Ituri originates from the mountains that limit the basin of Lake Alberto to the W. in the Congo near Basoko. Of much greater importance is the Ubanghi, an immense river, the largest of the tributaries of the Congo, which originates in the mountainous area of the Nilo-Congolese watershed, about 100 km away. west of Wadelai, and therefore took the name of Uellé, swollen by the Bomokandi and numerous other tributaries, often interrupted by rapids and waterfalls, it receives after Bondo the Bomu, which marks the border between French equatorial Africa and the Belgian Congo, assuming only then the name of Ubanghi; after which, forming a wide curve, it confuses its waters with those of the Congo at 50 km. to S. of the Equator. Throughout its journey the Ubanghi forms a border line between the possessions of France and those of Belgium and for almost 600 km. downstream of Zongo it offers a convenient river communication route. From the right, the Congo still receives the toll of other minor rivers, albeit always conspicuous and rich in water and partially navigable, such as the Sanga, the Kouyou and the Alima, which enter the main river in the downstream section of the Ubanghi confluence. The left tributaries are more numerous and overall of greater importance. The first one encountered downstream from Stanleyville is the Lomami, which originates in southern Catanga and, flowing in a direction parallel to that of the Lualaba, at a distance of 50-200 km., it enters the Congo at 130 km. downstream from Stanleyville, offering a convenient waterway for a considerable stretch of its lower course. Parallel to the Congo, from which it does not deviate on average more than 50 km., Is the Lulonga, called Lopori in its upper trunk, which, swollen by the Maringa at Basankusu, enters the Congo at about 100 km. to N. of the Equator. Just below the Equator, in Coquilhatville, flows the Ruki-Busira, which, with its numerous tributaries that convey the waters of a vast area of the central region, offers a wide network of river communications. But the most important of the left tributaries is the Cassai, which has its origins in Angola in the Bihé plateau and runs in a narrow valley up to the Wissmann waterfalls; after which, enriched by a very large number of tributaries that bear a conspicuous toll of waters, it becomes, starting from Charlesville, navigable for boats of 22 tons. Of its numerous tributaries, the largest is the Sankuru, which joins it on the right at Basongo, navigable from its confluence to Pania-Mutombo also for boats of 150 tons. Very conspicuous watercourses, tributaries of the Cassai, are also the Cango and the Giumo (Kwilu), which meet at their confluence in the Cassai in Bandundu and which with their sub-rivers form a navigable network of over 1200 km. which 650 km. also suitable for boats of over 22 tons.
Finally, among the tributaries of the Cassai we remember the Fini, emissary of Lake Leopoldo, a vast expanse of marsh of 2325 sq. Km., Which occupies the bottom of the Congolese basin and which can be considered, the last remnant of the internal basin that already covered it; from its exit from the lake, the Fini, which enters the Cassai at Mushie at 80 km. from the Congo, it measures 180 km. navigable for boats of 22 tons; its tributary Lukenie, which enters the Fini near the outflow of Lake Leopoldo II, is navigable up to Dekese (450 km.) for boats of less than 22 tons. The medium Congo ends in the Stanley Pool (Stanley Pond), a river lake of 1500 sq. Km, largely occupied by the island of Bamou at a height of 260 m., like an immense mountain stream, a path opens up through the mountain barrier of the Monti di Cristallo that separate it from the sea coast. The narrow and winding gorge that forms its riverbed narrows in some points up to 400 m., with depths ranging from 40 to 90 m., giving rise to 32 waterfalls or rapids in which copious waters rush with immense noise and speed. These falls took the name of Livingstone Falls, after the great Scottish traveler who first revealed the source region of the mighty river. The middle stretch of this section, from Manianga to Isangila, for a development of 140 km. however, it is free from waterfalls and therefore navigable for modest boats. But the regular navigability of the river as far as the ocean is then found in Matadi, where the new port accessible to sea navigation and the departure station of the railway line that directly reaches the Stanley Pool arise near the ancient village of Vivì. Downstream of Matadi begins the wide and deep estuary of the river, which penetrates the continent for 80 km., extending into the ocean for almost as much, as clearly appears from the examination of the marine bathymetric curves. The estuary, 15 to 17 km wide, is dotted with numerous islands, the largest of which is the island of Mateba inhabited by cattle breeders. At the mouth of the estuary, on the right or northern bank, in Belgian territory, stands the port of Banana; on the left or southern one, in Portuguese territory, that of Santo Antonio.