EVALUATION OF SEDIMENT MANAGEMENT STRATEGIES ON RESERVOIR STORAGE DEPLETION RATE: A CASE STUDY

Sedimentation aspects have a major role during the design of new reservoir projects because life of the reservoir mainly depends upon sediment handling during reservoir operation. Therefore, proper sediment management strategies should be adopted to enhance the life span of reservoirs. Basha Reservoir is one of the mega water resources projects which are being planned to construct on the Indus river. Under this study, the efficiency of four sediment management strategies were evaluated by using the RESSASS model. The reservoir management strategies considered for sediment simulation of Basha reservoir include the normal operation, raising of MoL, draw-down the MoL (flushing) and controlling the sediment inflows. Under normal operation, the model predicted the life span of Basha reservoir around 55-60 years. But by raising of Mol 2.0m/year implemented after 35 years of operation may add 10-15 years more to the life-span of the reservoir. However, by adopting the flushing operation to draw-down the MoL at El.1010m initiated after 35 years of operation, it may also add about 15-20 years more. Moreover, the results obtained by considering 50% reduction in sediment inflow due to implementation of river basin management projects upstream of Basha within 30 years of reservoir operation, depicts that the life of the reservoir will be more than 100 years. It is therefore concluded that proper sediment mitigation measure can significantly enhance the life-span of planned reservoirs.