Hydrological and ecological impacts of dams on the Kafue Flats floodplain system, southern Zambia

Developmental changes in river basins in Africa have become a reality. Many wetland ecosystems have been impacted by dams and other hydrological interventions resulting in both foreseen and unexpected consequences. The Kafue Flats in southern Zambia is an extensive floodplain system that lies within the middle Kafue river basin. The floodplain is about 255 km long and 60 km wide, covering an area of approximately 6,500 km2. It is currently sandwiched between two large dams which are approximately 270 km apart. These dams have completely altered the hydrological regime of the system. Backwater from the downstream dam and releases from upstream have created a permanently flooded area within the floodplain that was not present in the past. Elsewhere, flooding has been reduced. The ecological consequences of these changes for the floodplain, which hosts two national parks (both Ramsar sites), have been extensive. Hydrological and vegetation changes have impacted the habitat for important wildlife communities including the endemic antelope, Kobus leche kafuensis. The most dramatic change in vegetation is associated with the colonisation of parts of the floodplain by the invasive alien plant, Mimosa pigra. This paper discusses these changes and their potential consequences.