Sediment management studies of a run-of-the-river hydroelectric project using numerical and physical model simulations

Abstract

ABSTRACTRun-of-the-river hydropower projects are developed based on the concept of sustaining reservoir life by sediment management. Sediment management is achieved by sluicing or drawdown flushing through low-level spillways. Simulations with numerical and physical models are essential for optimizing the design and operation of such projects. In this paper, numerical and physical model simulations carried out for sediment management of a run-of-the-river hydropower project are presented. For Devsari Hydroelectric Project, Uttarakhand, India, a physical model was constructed to a geometrically similar scale of 1: 60. Experiments were carried out for sediment management for various scenarios. One-dimensional model Hydrologic Engineering Center's –River Analysis System was used to simulate the longitudinal sedimentation and velocity profiles in the physical model. The numerical model was further applied to the prototype for predicting the long-term sediment deposition along the reservoir stretch. Results of the simulation indicated deltaic sediment deposition in the upstream reaches of the main Pinder and Kailganga rivers. The delta advanced towards downstream for lower reservoir operation levels. The flow velocities in the entire reservoir stretch were observed to be very low, thus confirming the design concept of reservoir functioning as a desilting basin. Experiments were carried out on the physical model for simulating sediment removal by drawdown flushing. It was observed that reservoir capacity can be restored by annual flushing during peak flows. Flushing with discharge of 300 m3/s for 12 h duration can remove about 0.0086 Mm3 of sediment and hence may be adopted for reservoir operation.