Study on Sediment Management Strategy of Sandy River Reservoir

Abstract

The establishment and operation of one hydropower complex will change the movement law of water flow and sediment of the river way, and sediment deposition is difficult to avoid. Due to the characteristics of “high utilized water head, small reservoir storage, high sediment content and particle hardness” of proposed Upper Arun Hydroelectric Project, this paper applies one-dimensional hydrodynamic & sediment model to studying the movement law of flow and sediment of 3 different sediment management strategy, then finding the rational one which can not only maintain a sustainable live storage of the reservoir by sediment flushing, but also reduce sediment abrasion to turbines. The results show that, when the proposed fully open of all low-level outlets for sediment flushing being implemented during high flow periods, the difference of sedimentation is relatively minor, which all 3 options can effectively maintain the live storage of the reservoir thereby minimizing deposition of sediment at the places that will affect project operation. Therefore, the selection of sediment management strategy should depends on the comprehensive technical and economic comparison. Due to the advantages of relatively short outage periods, conventional technology of construction and the largest Net Present Value, the appropriate sediment desilting operation mode is applying a sediment bypass tunnel with its intake located in the middle of reservoir, and meanwhile utilizing the reservoir’s sedimentation effect, to reduce sediment content transported through the turbines.