Abstract: In order to understand the impact of a long series water and sediment process on the adjustment of reservoir bed, we simulated the scouring and deposition and deformation in the downstream reservoir of Tianchi pumped storage power station using MIKE based on water level fluctuation in the downstream reservoir. Through calibration of parameters and model validation, we obtained the long series total deposition amount and sediment delivery ratio of the reservoir as well as the deposition profile along stream and deposition process of characteristic reaches.Results suggest that the sedimentation of reservoir corresponds with the water and sediment process. Sedimentation mainly displays a delta shape, focusing in the range of 0.5-1.8 km upstream the dam.Affected by hydraulic and boundary condition, the deposition features and deposit compositions of different reaches vary correspondingly. Floods of certain frequency has a significant influence on deposition amount despite that flood does not occupy much of the flow-sediment series. Flood dispatching and operation of power station must be adjusted and optimized to enhance sediment delivery ratio and reduce sedimentation. The research results are in agreement with those from scale model test, hence could offer technical parameters for the reservoir dispatching operation.

Key words: pumped storage power station, downstream reservoir, long series, numerical simulation, deposition, sediment delivery ratio, focus of deposition