Ruzizi River

The Ruzizi (also sometimes spelled Rusizi) is a river, 117 kilometres (73 mi) long, that flows from Lake Kivu to Lake Tanganyika in Central Africa, descending from about 1,500 metres (4,900 ft) to about 770 metres (2,530 ft) above sea level over its length. The steepest gradients occur over the first 40 kilometres (25 mi), where hydroelectric dams have been built. Further downstream, the Ruzizi Plain, the floor of the Western Rift Valley, has only 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 watershed of the Nile and instead forced the lake overflow south down the Ruzizi and the watershed of the Congo.

Course

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.