Application of mathematical model on deposition study of pumped-storage power reservoir

Abstract

Sediment deposition can cause a reduction in reservoir capacity and hydro-mechanical abrasion of pumped-storage power stations (PSPSs). To increase the operating efficiency and service life of PSPSs, sediment deposition in the process of reservoir water transfer needs to be addressed. Combined with hydrodynamics, reservoir sedimentation theory and a numerical model, a two-dimensional sediment model of the lower reservoir of Tianchi PSPS was established. Considering the characteristics of the upper and lower reservoirs of this PSPS, water and sediment exchange between the reservoirs was realised by setting source and sink terms. The process and distribution of sediment deposition were analysed over 50 years. Sediment deposition in the lower reservoir of the PSPS was found to be 0.5–1.8 km in front of the dam and triangular. The main stream of sediment-carrying flow could be moved from the right-hand channel to the sediment discharge tunnel and spillway by setting up a sediment discharge trench. The average sedimentation thickness of the reservoir during 10 years of operation was about 0.8 m with a sediment intercept weir (SIW) established, while it was more than 4.2 m in the main stream area outside the SIW. For operation of 50 years, these values were 3 m and 10 m, respectively. The SIW effectively reduced deposition near the inlet (outlet) of the PSPS, the amount of sediment passing the machine and deposition to the dam front. The results provide a reference for simulations and preventive measures of sediment deposition in PSPSs.