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Lake Kivu () is one of the African Great Lakes.

It lies on the border between the Democratic Republic of the Congo and Rwanda, and is in the Albertine Rift, the western branch of the East African Rift. Lake Kivu empties into the Ruzizi River, which flows southwards into Lake Tanganyika. In the past, Lake Kivu drained toward the north, contributing to the White Nile. About 13,000 to 9,000 years ago, volcanic activity blocked Lake Kivu's outlet to the watershed of the Nile. The volcanism produced mountains, including the Virungas, which rose between Lake Kivu and Lake Edward, to the north. Water from Lake Kivu was then forced south down the Ruzizi. This, in turn, raised the level of Lake Tanganyika, which overflowed down the Lukuga River. Lake Kivu is one of three lakes in the world, along with Lake Nyos and Lake Monoun, that undergo limnic eruptions (where overturn of deepwater stratified layers releases dissolved carbon dioxide (CO2)).

Lake Kivu is approximately 42 km (26 mi) long and 50 km (31 mi) at its widest. The world's tenth-largest island in a lake, Idjwi, lies in Lake Kivu.

Lake Kivu is a meromictic lake containing a freshwater surface layer that becomes more saline with depth, with a salinity approaching 6 g/kg near the bottom. The trigger for lake overturns in Lake Kivu is unknown, but volcanic activity and changes in climate are both suspected. In Lake Kivu's case, it includes methane (CH4) and carbon dioxide (CO2), as a result of lake water interaction with volcanic hot springs. A future overturn and gas release from the deep waters of Lake Kivu would result in catastrophe, dwarfing the historically documented lake overturns at the much smaller Lakes Nyos and Monoun. The carbon dioxide would then suffocate large numbers of people in the lake basin as the gases roll off the lake surface. The risk posed by Lake Kivu began to be understood during the analysis of more recent events at Lake Nyos. An experimental vent pipe was installed at Lake Nyos in 2001 to remove gas from the deep water, but such a solution for the much larger Lake Kivu would be considerably more expensive.

Lake Kivu has recently been found to contain approximately 55 billion m3 (1.9 trillion cu ft) of dissolved biogas at a depth of 300 metres (1,000 ft). In addition, Symbion Power Lake Kivu Limited was awarded a Concession and Power Producing Agreement (PPA) in 2015, to produce 50 MW of power using Lake Kivu methane.

The fish fauna in Lake Kivu is relatively poor with 28 described species, including four introduced species. The exploitable stock of the Lake Tanganyika sardine was estimated at 2,000–4,000 metric tons (2,000–3,900 long tons) per year. It was introduced to Lake Kivu in late 1959 by the Belgian agronomist Alphonse Collart. At present, Lake Kivu is the sole natural lake in which L. miodon, a sardine originally restricted to Lake Tanganyika, has been introduced initially to fill an empty niche. Prior to the introduction, no planktivorous fish was present in the pelagic waters of Lake Kivu. The elevation of the mountains west of the lake (which is currently the Kahuzi-Biega National Park, one of the largest reserves of eastern lowland (or Grauer's) gorillas in the world), combined with the elevation of the eastern rift (located in eastern Rwanda) would be responsible for the drainage of water from central Rwanda in the actual Lake Kivu. This concept of "proto-lake Kivu" was challenged by lack of consistent geological evidence, although the cichlid's molecular clock suggests the existence of a lake much older than the commonly cited 15,000 years. Lake Kivu is the home of four species of freshwater crab, including two non-endemics (Potamonautes lirrangensis and P. mutandensis) and two endemics (P. bourgaultae and P. idjwiensis). Among Rift Valley lakes, Lake Tanganyika and Lake Victoria are the only other with endemic freshwater crabs.

Quick Facts

• Lake Kivu is one of three lakes in the world, along with Lake Nyos and Lake Monoun, that undergo limnic eruptions (where overturn of deepwater stratified layers releases dissolved carbon dioxide (CO2)).
• Lake Kivu empties into the Ruzizi River, which flows southwards into Lake Tanganyika.
• The volcanism produced mountains, including the Virungas, which rose between Lake Kivu and Lake Edward, to the north.
• In addition, Symbion Power Lake Kivu Limited was awarded a Concession and Power Producing Agreement (PPA) in 2015, to produce 50 MW of power using Lake Kivu methane.
• At present, Lake Kivu is the sole natural lake in which L. miodon, a sardine originally restricted to Lake Tanganyika, has been introduced initially to fill an empty niche.

Source material: Wikipedia - "Lake Kivu". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.