Coastal Impacts of Water Abstraction and Impoundment in Africa: the Case of Rufiji River

Abstract

Construction of large dams with reservoir type storage impound water behind them for seasonal annual, and in some cases for multi-annual storage and regulation of a river. Similarly, tubewells abstract surface and ground water bodies from their natural flow. The impoundment of water by damming and its abstraction through tubewells are common practices in the world and even within the Africa region (WCD, 2000). Globally, the number of large dams has grown at a tremendous pace during the last 50 years (Fig. 1.1) The fast growth in dam construction is driven by an increasing demand of water from urban and rural communities for reliable freshwater supply, agricultural irrigation and hydro-electric power. As these practices become more widespread, they are leading to significant reductions in the fluxes of water and river-borne sediment that are discharged through catchment to coastal sea systems. These flux reductions are contributing to changes in the state of the coastal environment and these changes are in turn impacting coastal communities through issues including coastal erosion, estuarine salinisation and the depletion of nutrients in the coastal sea.