Zambezi River Basin

© R. J. Boroto

The delivery of safe drinkingwater inmost of the basin’s urban areas is hindered by old and inadequate infrastructure.

Wetlands

Some wetlands in the Zambezi River Basin are receding due to reduced flows caused by droughts and water extraction. Other wetlands are increasingly being infested by aquatic weeds while still others are exposed to persistent organic pollutants such as DDT, the pesticide dichlorodiphenyltrichloroethane. Some wetlands have also been inundated with water as a result of dam construction. Additional threats to wetlands include overexploitation of resources, uncontrolled fires, pollution and deforestation. These threats alter wetlands, causing habitat change and species loss (Chenje 2000). The Lower Shire River in Malawi, the Zambezi Delta in Mozambique, the Kwando/Linyanti/ Chobe system draining down the Caprivi in Namibia, and the Kafue flood plains in Zambia are the most environmentally sensitive wetlands in the basin (Bethune 1999). The Kafue Flats The Kafue Flats in southern Zambia are an extensive floodplain system that lies in the middle Kafue River. The floodplain covers an area of approximately 6 500 sq km, and is sandwiched between two large dams, which are 270 km apart (Mumba and Thompson 2005). The dams have altered the hydrological regime of the system, with backwater from the Kafue Gorge Dam downstream and releases from the Itezhi-

Tezhi Dam upstream creating a permanently flooded area in the floodplain. The hydrological and vegetation changes have affected the habitat for important wildlife communities including the endemic lechwe antelope, ( Kobus lechwe kafuensis ). The other dramatic change in vegetation is the colonization of parts of the floodplain by the invasive alien plant, Mimosa pigra (Mumba and Thompson 2005). The Kafue River and its floodplains are heavily utilized and highly industrialized, and subjected to pollution from mining, industry, agriculture and municipalities. A joint study by the University of Zambia and the Swedish Lulea University of Technology shows high levels of heavy metals, particularly copper, in the Kafue River near the Copperbelt area. The floodplain also suffers from heavy grazing and overfishing (SADC and SARDC 2008). The Zambezi Delta Water regulation from Cahora Bassa dam has substantially reduced the Zambezi Delta wetland productivity and even offshore shrimp catches in Mozambique (Chenje 2000). Saltwater intrusion has become a problem in the delta as a result of reduced freshwater flows and the lack of regular substantial seasonal floods. Irregular floods in the delta are associated with cyclonic rainfall along the Mozambique coast.

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