Modeling Sediment Yield and Deposition in Rusumo Reservoir Using SWAT

Sedimentation impacts many infrastructures including river regulation works, reservoir, etc. This has attracted increasing attention from the public and engineers. Recently, the Rusumo Falls hydroelectric project has been approved. The falls are located on the Kagera River whose tributaries; Nyabarongo and Ruvubu Rivers, are known for their high sediment load content. The high concentrations in sediment lead to the sedimentation of the reservoir and consequently to a loss of storage capacity within a short period. For a proper planning and management of the reservoir, an anticipated quantification of sediment yield and deposition was carried out using the Soil and Water Assessment Tool (SWAT). The SWAT model produced information on sediment yield which was fed into the empirical methods i.e. Ort (1930) and the method of rate of storage capacity loss. The results showed that part of the sediment will be deposited in the wetland area far upstream of the dam, and the remaining part in the pool just behind the dam. A loss of 2.5-10% of the storage capacity of the reservoir was predicted within a period of ten years after the commissioning of the project.