African Water Development Report 2006 - United Nations Economic ...

African Water Development Report 2006areas. Most African reservoirs are of seasonal,weekly and daily storage regulation. Among thereservoirs of carry-over storage, the Nasser Reservoiron the Nile River should be mentioned.This reservoir which was built in the 1970s isof great importance for the economy of Egypt.The construction of multipurpose water managementsystems, including reservoirs and canalsfor river runoff redistribution in time and space(among various river basins), is the most effectiveway for man’s impact on the hydrographicnetwork (Shiklomanov, 2002). The largest multipurposewater management system in Africa,with water transfers is under operation in SouthAfrica. This complicated hydraulic system consistsof a reservoir, canals, tunnels, and pumpingstations. It connects the Orange and LimpopoRivers and other coastal rivers and is intended toimprove water supply to industrial centres andfor irrigation development. The amount of watertransferred by this system equals 3 to 4 km 3 /year;and stretches over a distance of several hundredskilometres (Ibid).Table 6.3: Principal Reservoirs in AfricaReservoir Country Basin Year of filling up Capacity, km 3Owen Falls(Lake Victoria)NasserKaribaVoltaCabora BassaKossouSuanityKainjiUganda, Kenya,TanzaniaEgyptZambia,ZimbabweGhanaMozambiqueCôte d’IvoireGuineaNigeriaRiverVictoria-NileNileZambeziVolta RiverZambeziBandamaKonkureNigerSource: I.A.Shiklomanov, Regional Distribution of Rivers and Streams in Africa, 2002.19541970195919651977197219611968205169160148622817.215Pollution of Aquatic BodiesThe damage that eutrophication and the proliferationof invasive aquatic plants can do to thequality of surface water, such as rivers and lakes,has already been mentioned in the precedingparagraph, and includes pollution. Water hyacinth(Eichhornia crassipes) and Salvinia molestaweeds are the main culprits. These weedswhich are yet to be effectively controlled alsodisrupt water transport, water supplies to urbanareas, the fishing industry, power generation andthe livelihoods of many local communities. Likethem, poor sanitation and uncontrolled wastedischarges increase the cost for downstreamusers and affect public health. In most Africancountries, the menace of water pollution emanatesmore from microbiological sources thanfrom chemical due to uncontrolled human andanimal faecal disposal. An example of the waterquality status of water sources is shown forCameroon in table 6.4, while the natural physicalquality parameters of both surface and groundwater sources are shown for Congo in table 6.5(AWDR National Reports, 2003).132