Sediment impacts in Africa's transboundary lake/river basins: Case study of the East African Great Lakes

Abstract

The current population pressure, inappropriate cultivation practices, forest removal and high grazing intensities on forests, wetlands, rangelands and marginal agricultural lands leads to unwanted sediment and stream flow changes that mainly impacts the downstream human and natural communities. Forests and bush are cleared, and wetlands are encroached to create space for human settlement, roads construction and to satisfy wood fuel energy demands. Similarly, pastoral areas are subjected to growing human and livestock populations, leading to land degradation, soil erosion and to an increase in the load of non-point pollutants. Landscape disturbance over many decades, and the resulting increase in soil erosion and sedimentation is the dominant cause of the ongoing eutrophication in many of the lakes in eastern Africa. Increased sedimentation in the rivers and lakes has many impacts. For example, it has altered some aquatic habitats and communities, contributed to increasing eutrophication, abetted the proliferation of algal blooms and water hyacinth reduced the amount of dissolved oxygen, etc. This paper outlines some of the problems created by increased sedimentation within the East African Great Lakes basin, and provides some possible solutions to the mitigation of sediment flux through integrated sediment management approaches.