Loss of hydropower caused by upstream water diversion: A case study of Pingshang water diversion project in Shanxi, China

For water diversion projects, both the economic benefits from solving water shortage for water supply area and the effects on economy and environment for water source site should be highly valued. This paper analyzes the influence of diversion volume and selection of water source sites on the loss of cascade and parallel hydropower plants downstream and presents an optimization diversion scheme for the minimum energy loss based on the minimum ecological base flow of the water source site and the downstream river via a case study of Pingshang water diversion project in Shanxi province, China. The results show that energy output increases greatly with river runoff increase and energy loss cuts down as the volume of upstream diversion reduces. When water source site of diversion projects lies in the upstream parallel plants, optimal allocation of diversion volume depends mainly on distribution of the downstream power stations, the total installed capacity of cascade hydropower stations and the individual kinetic energy characteristics. The optimization diversion scheme of the project studied based on the minimum ecological base flow could cut down 13.7% of energy loss compared with the scheme that water diverted symmetrically from two parallel rivers.