Ruzizi River

Ruzizi River
Hippopotami in the Ruzizi River in Burundi
Country	DR Congo (DRC) Rwanda Burundi
Source	Lake Kivu
- location	border between Bukavu and Cyangugu, South Kivu, DRC & Western Province, Rwanda
- elevation	1,472 m (4,829 ft)
- coordinates	02°29′27″S 28°53′35″E / 2.49083°S 28.89306°E / -2.49083; 28.89306
Mouth	Lake Tanganyika
- location	west of Bujumbura, Burundi, Bujumbura Rural Province
- elevation	768 m (2,520 ft)
- coordinates	03°21′51″S 29°16′04″E / 3.36417°S 29.26778°E / -3.36417; 29.26778Coordinates: 03°21′51″S 29°16′04″E / 3.36417°S 29.26778°E / -3.36417; 29.26778
Length	117 km (73 mi)
Discharge
- average	100 m3/s (3,531 cu ft/s)

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.

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 among Europeans that this was not the case. The Ruzizi flows into Lake Tanganyika, which overflows into the Lukuga River about 120 kilometres (75 mi) south of Ujiji. The Lukuga flows west into the Lualaba River, a major tributary of the Congo.