Figure 1-1: A satellite composite image of Africa (Source: NASA) viii Africa’s Lakes Introduction een from space, the Earth appears Africa, with a total area of 30 244 050 the world, many of which are bordered by 1as a largely blue planet, suggesting km2 (11 677 293 square miles), is the two or more countries. Lake Victoria is the S the presence of vast quantities of second largest and second most populous largest of all African lakes and the sec- water. Although this is true, only about two continent after Asia. It covers approxi- ond largest freshwater body in the world, per cent of the Earth’s water is fresh, with mately 20.3 per cent of the total land area with a surface area of about 68 800 km2 the majority of this small fraction locked on Earth. With over 800 million people, (27 000 square miles). Its extensive sur- up in icebergs and glaciers, or located far it accounts for about one seventh of the face is divided among three countries: the underground beyond our easy reach. Lakes world’s population (Wikipedia 2005). It is northern half to Uganda, the southern half appear like blue diamond mosaics in the also the largest of the three great south- to Tanzania, and part of the northeastern terrestrial mass. As a relative perspective, if ward projections from the main mass of sector to Kenya. all the water on Earth could be put into a the Earth’s surface. It is estimated that According to the WORLDLAKE data- 3 four-litre bottle, the readily-available quan- Africa has about 30 000 km (7 197 cubic base, there are 677 lakes in Africa, with tity for use by people would be about one miles) of water in large lakes (Anon 1978; 88 of them listed as principal lakes (see tablespoon, or less than half of one per WCMC n.d.), which is the largest volume Appendix). Although lakes are a source of cent of the total. Nevertheless, even this of any continent. livelihoods in most African societies, they small amount is deemed suffi cient to meet Africa is endowed with hundreds of are also a major source of natural disas- all the present and foreseeable people’s lakes, both natural and artifi cial (Table ters, tropical diseases and pandemics. It is needs – if it were evenly distributed around 1.1). For example, Lake Bosumtwi is a important to note that Africa’s lakes are the world and protected from degradation. natural lake that was formed by a crater also undergoing signifi cant changes due A lake is defi ned as a large body of when a large meteoroid smashed into to a combination of human activities and water, usually fresh water, which is sur- the continent. Lake Nasser, on the other climate change, with potentially serious rounded by land. Lakes are usually formed hand, is a reservoir or artifi cial lake created implications for people’s livelihoods and when natural depressions or basins in the behind the Aswan Dam in Egypt. Africa is aquatic biodiversity. land surface become fi lled with water over also home to some of the largest lakes in time. They can range from small ponds to water-bodies stretching hundreds of kilo- Lake Tonga Lake Ichkeul Lake Al Wahda metres and containing vast quantities of water; large lakes are sometimes referred to as ‘inland seas’. Some small seas are also often referred to as lakes (Wikipedia 2005). As defi nitions of what constitutes a lake also vary, the precise number of the Toshka Project world’s lakes is diffi cult to determine. Lake Nasser In contrast to fl owing streams and rivers, lakes provide a means for pooling Lake Djoudj Lake Chad or storing water for varying periods of Lake Manantali time. Lakes are one of our most important Challawa Lake Tana Gorge Reservoir natural resources, especially in the tropics, Lake Volta where they form highly productive biologi- Lake Nyos Songor Ch’ew Bahir cal systems. They provide water for con- Lagoon Lake Monoun Lake Turkana sumption, fi shing, irrigation, power gen- Lake Albert eration, transportation, recreation, and a Lake Kyoga Lake Ntomba Lake Edward Lake Nakuru variety of other domestic, agricultural and Lake Mai-Ndombe Lake Kivu Lake Victoria industrial uses (Zinabu 1998). Lake Eyasi Natural and human made lakes and Lake Tanganyika Lake Rukwa wetlands provide signifi cant storage of KEY Lake Mweru somewhat easily accessible global terrestrial Study Lakes Lake Bagweulu Lake Malawi water, which varies seasonally and annually Other Major Lakes Lake according to climate variation and anthro- Cahora Basa Lake Chilwa Lake Alaotra Lake Kariba pogenic activities. There are approximately Lake Chivero 50 000 natural lakes and 7 500 human made lakes in the world (Ryanzhin 2004). Despite the publication of several world lakes datasets and databases (Herdendorf Lesotho Highlands Lake Sibaya Reservoir 1982; Birkett, Mason 1995; ILEC 2002; Lake St. Lucia Wetlands International 2002; Lehner, Döll N 2004), most data on limnologically studied 0 500 1000 Kilometres natural and human made lakes are dis- persed over a wide range of literature. Figure 1.1: Distrubution of Africa’s major lakes UNEP/GRID–Sioux Falls 1 The Mankwe Dam in Pilanesberg National Park, South Africa. Unknown/UNEP/MorgueFile Table 1.1: Africa’s lakes by country Africa, and particularly East Africa, has research focusing particularly on Lakes numerous lakes that support very impor- Victoria, Tanganyika and Malawi. However, Country # of Lakes Percentage tant fi sheries —providing a livelihood governmental support for lakes remains Uganda 69 10% to millions of people, and contributing low in many African countries, with little signifi cantly to the food supply. In many of money allocated from national budgets for Kenya 64 9.50% these lakes, however, fi sheries are reach- their conservation or development Cameroon 59 8.70% ing a state of maturity and unsustainabil- (Petr 2005). Tanzania 49 7.20% ity. The fi sheries of just 11 lakes in the 11 Although Africa’s lakes are limited and Ethiopia 46 6.80% countries of eastern Africa employ close to sensitive resources that call for proper care half a million people, with perhaps three South Africa 37 5.50% and management, they remain among the times as many engaged in secondary activi- most abused of the continent’s natural re- Rwanda 29 4.30% ties and related services—thus supporting sources. The direct disposal of wastewater Ghana 29 4.30% about four per cent of the region’s entire into lakes continues to have a damaging Morocco 26 3.80% population (Petr 2005). This has also impact on their fragile ecological balances. resulted in transboundary water confl icts, Madagascar 25 3.70% Human impacts in lake basins and catch- despite the creation of regional initiatives ments also have devastating consequences Egypt 16 2.40% on integrated water management. Trans- for the lakes themselves, including: rapid Nigeria 16 2.40% boundary freshwater resources will clearly siltation caused by accelerated soil erosion; Mali 15 2.20% become a source of growing confl ict in irreversible uptake of water and/or salini- Tunisia 15 2.20% Africa without the development of—and sation due to irrigation; eutrophication; adherence to—sound multilateral agree- Zaire 15 2.20% contamination with toxic chemicals and ments for their shared management. mine tailings; and acidifi cation. Effec- Malawi 13 1.90% The degree of resource utilisation tive integrated watershed management Botswana 12 1.80% differs greatly from lake to lake, and ac- requires not only strict soil conservation Gabon 8 1.20% cording to the two main types of fi sheries: measures, but changes in the way that Others 134 <20% demersal/onshore and pelagic/offshore. water moves through the agro-ecosystem. Currently, demersal/onshore resources Total 677 100% In Africa, human factors, in combina- are being more heavily exploited or over- tion with the natural conditions of climate Source: World Lakes Network (2004) exploited. Africa’s large lakes are receiving and geology, may infl uence water quality considerable biological attention through to a large extent. Some African nations do a number of international activities, with 2 not have industries that fl ourish in devel- • The multiplicity of transboundary in meeting competing demands for basic oped countries, and pollutants are not pro- water basins water supplies (World Commission on Wa- duced in such large quantities. However, • Extreme and temporal variability of ter for the 21st Century n.d.). pollution resulting from land-use changes, climate and rainfall Water supplies are undoubtedly one of environmental modifi cation and other • Growing water scarcity the most important resources for Africa’s practices associated with rapid population social, economic and environmental well- • Shrinking of some water bodies increase, have caused or accelerated many being. Currently, about two-thirds of the changes in the continent’s lakes (Zinabu • Desertifi cation rural population and one-quarter of the 1998). The major human threats include: urban population are without safe drink- The main threats to water quality in Af- • The pursuit of inappropriate gover- ing water, and even higher proportions rica include eutrophication, pollution, and nance and institutional arrangements lack proper sanitation. Climate change will the proliferation of invasive aquatic plants in managing national and transnational likely make the situation even worse. The such as the water hyacinth. Industrial water basins greatest impact will continue to be felt by wastes are still discharged without treat- • The depletion of water resources the poor, who have the most limited access ment into rivers and lakes in most African through pollution, environmental deg- to water resources (Watson et al. 1997). countries, posing a major and persistent radation, and deforestation Other threats to Africa’s lakes include: health problem.