Sedimentation of Reservoirs

It is well known that the useful life of reservoirs intended for irrigation, flood control and hydraulic developments is reduced by deposition of suspended sediment, bedload and bed material brought down by the rivers. In India the quantity of sediment deposit in reservoirs is generally assumed from the sediment observations carried out on the rivers in the planning stage. Broad aspects of sedimentation commonly used for prediction of the life of reservoirs have been dealt with. The method of determination of rate of sedimentation adopted by the Central Soil Mechanics Research Station, Central Water and Power Commission, has been described giving the technique of estimation of suspended sediment adopted in India. Also the role played by the bedload and unit weight of sediment is given along with the method of computation of sedimentation of reservoirs. The observed rate of sedimentation of reservoirs in India particularly of Bhakra, Maithon, Panchet, Hirakud, Mayrakshi, and Krishnarajasagar has been compared by actual sedimentation surveys carried out recently on each of them.