Ruzizi River

The Ruzizi (also sometimes spelled Rusizi) is a river, long, that flows from Lake Kivu to Lake Tanganyika in Central Africa, descending from about to about above sea level over its length. The steepest gradients occur over the first , where hydroelectric dams have been built. Further downstream, the Ruzizi Plain, the floor of the Western Rift Valley, has gentle hills, and the river flows into Lake Tanganyika through a delta, with one or two small channels splitting off from the main channel. The Ruzizi is a young river, formed about 10,000 years ago when volcanism associated with continental rifting created the Virunga Mountains. The mountains blocked Lake Kivu's former outlet to the drainage basin of the Nile and instead forced the lake overflow south down the Ruzizi and the drainage basin of the Congo. Along its upstream reaches, the river forms part of the border between Rwanda on the east with the Democratic Republic of the Congo (DRC) on the west. Further downstream, it forms part of the border between the DRC and Burundi, and its lowermost reach lies entirely within Burundi. To the west, the Fizi Baraka mountains tower over the river. The Bridge of Concord, Burundi's longest bridge, crosses the river near its mouth. Tributaries of the Ruzizi River include the Nyamagana, Muhira, Kaburantwa, Kagunuzi, Rubyiro and Ruhwa, among others. The Ruzizi River, flowing south into Lake Tanganyika, is part of the upper watershed of the Congo River. Nineteenth-century British explorers such as Richard Francis Burton and John Hanning Speke, uncertain of the direction of flow of the Ruzizi, thought that it might flow north out of the lake toward the White Nile. Their research and follow-up explorations by David Livingstone and Henry Morton Stanley established that this was not the case. The Ruzizi flows into Lake Tanganyika, which overflows into the Lukuga River about south of Ujiji. The Lukuga flows west into the Lualaba River, a major tributary of the Congo. Rifting, the slow pulling apart of a tectonic plate, has produced the East African Rift system and its many basins and lakes.