Estimation of Delta Profile in the Indravati Reservoir

In case of the Upper Indravati Hydro Electric Project in the Orissa state of India, the topography of the reservoir area governed the location of the water intake, which is situated about 6.6 km from the upstream edge of the water spread. The total length of the reservoir is 43 km. When the delta arrives at the intake, the water draws a heavy charge of sand and coarser sediment that will damage the turbines. Reasonably accurate prediction of the period required for the sediment delta to travel down to the intake position therefore achieved crucial importance. Three different methods were used to predict the time rate of delta development: (1) a mathematical model; (2) the empirical procedure developed by the U.S. Bureau of Reclamation (USBR), based on the observations about the topset slope, foreset slope, and pivot point, made when the reservoir is in operation; and (3) a procedure based on sediment distribution following the empirical area reduction method. Results achieved by each of the three methods compared well, indicating that such comparative analysis increases confidence in quantitative predictions and improves the predictive methods for delta profile.