Lakes

Lakes are the source of many great rivers in Africa, provide enormous amounts of fresh water fish and water to many of the continents inhabitants and are home to unique aquatic and terrestrial species. Africa holds some of the largest lakes in the world.

Africa’s largest lakes are Lake Victoria (Lake Ukerewe), Lake Chad, in the centre of the continent, and Lake Tanganika, lying between the Democratic Republic of Congo, Burundi, Tanzania and Zambia.

Livelihoods

Lakes are important resources of water for agriculture, household use, but of course of fish. Sithole estimated that lakes in Africa support 16-17 per cent of inland fisheries, making Uganda one of the largest freshwater fish producers in the world. Across much of the continent, lake freshwater fisheries provide an important source of food and livelihood for millions of people.

Photo: Lake Magadi. By Vic Klabbers

Great lakes

The most important lake area in Africa is undoubtedly that of the Great Lakes. The African Great Lakes are a series of lakes constituting the part of the Rift Valley lakes in and around the East African Rift. They include Lake Malawi (or Lake Nyasa), with over 500 endemic fish species, and Lake Victoria. Their high lake plateau contains the headwaters of both the Nile and the Congo rivers.

Lake Victoria is the size of Ireland and second largest fresh water lake in the world in terms of surface area. Lake Victoria receives its water from many rivers, the largest being the Kagera. The lake then drains into the Nile through Owen Falls, where there is a man-made hydroelectric dam. Locals introduced the Nile perch, which became the top predator wiping out many endemic fish species.

Also part of the Great Lakes is Lake Tanganyika, the world's second largest in volume as well as the second deepest. Lake Tanganyika’s only outlet is the Lukuga River, which flows into the Congo River. It is home to hippos and crocodiles and varieties of fish, of which are almost 200 unique Cichlid species.

Threats

Despite their beauty, these great lakes rank as one of the world's most endangered water systems. Deforestation, agricultural and industrial pollution, urban waste water and overfishing severely affect the health of many of the lakes and their water basins.

Then there are the threats to rivers that also impact Africa’s lakes. Huge hydropower dams with extensive reservoirs decrease the critical water flow, but also block the routes of many migratory species, such as fish and manatees. These dams are found throughout the continent: Kariba on the river of Zambezi, Asuan in Egypt on the river of Nile, and the biggest dam of the continent: Akosombo on the Volta River in Ghana (Fobil 2003). Furthermore, extensive irrigation for cash crop cultivation and other agriculture put severe limits on water availability, causing lake water levels to drop and turning permanent rivers into seasonal streams. On the African continent as a whole, 85 per cent of water withdrawals are used for agriculture-and the percentage is even higher in sub-Saharan Africa.

Example: Lake Natron, Kenya

Lake Natron in Kenya is Africa’s most important Wetlands of International Importance. It is the only breeding site of the East-African population of Lesser Flamingo. The Lake Natron Basin – being part of the Serengeti ecosystem - was listed as Tanzania’s second Ramsar site in 2001. The 58 x 15 km lake which is only 0.5 – 2 m deep was nominated as a Wetland of International Importance under the Ramsar Convention on Wetlands as a representative example of a Rift Valley soda lake in East Africa. However, the Lake is under severe threat by the renewed plans by the Tanzanian government to mine for soda ash in the lake. Read more

Example: Lake Ichkeul, Tunisia

Lake Ichkeul  (photo top) is one of only four major wetlands in Africa that have been declared as a World Heritage Site. The Ichkeul National Park is part of an estuarine wetland system on the Mediterranean coast of Tunisia, where 250,000 ducks, geese and coots used to over-winter. Numbers were drastically reduced - to about a tenth of that number - as a result of dam construction and water abstraction upstream. By developing a water resource allocation decision-making tool, we introduced equitable water use for all users, as well as biodiversity. Read more

Example: Lake Chad

In Lake Chad, a lake shared by Cameroon, Chad, Nigeria and Niger, climate change, the demand for irrigation water upstream, and poor management decisions in the basin have reduced the size of the lake by 90% over the past 40 years. The net effect on the 20 million people, mainly fishers and farmers, who rely directly on the lake is rising levels of malnutrition, in turn leading to a much increased vulnerability to diseases. Read more