Analysis of siltation causes in the downstream of Xiangjiaba Hydropower Station on Jinsha River in 2020
The changes of sediment scouring and siltation in the downstream of Xiangjiaba Reservoir have a significant impact on bank slope stability and navigation.After the operation of Xiangjiaba Hydropower Sta-tion,the downstream riverbed of the dam remained in a state of erosion until silting first appeared in 2020.The sediment discharging from the Xiangjiaba Reservoir and the riverbed scouring and siltation in the down-stream reach are calculated by using sediment-transport balance and topographic change methods,the causes of siltation in the downstream of Xiangjiaba in 2020 are analyzed based on meteorological,hydrodynamic and field survey data.The results show that the annual runoff out of the reservoir does not change much after the water storage in Xiangjiaba,and the sediment out of the reservoir is greatly reduced by the sediment retention effect.In 2020,the downstream tributaries of Xiangjiaba had abundant rainfall,and sediment transported from the tributaries increased significantly,which resulting in a regional strong sediment transport process.The highest water level in this year at each downstream control station is higher than the historical average water level,the water surface gradient during the flood season does not change much,thus the sediment carrying ca-pacity is insufficient to transport significantly increased sediment.In addition,with the reduction of sand min-ing,the sandpits with large downward cutting occurs re-silting.The above reasons cause channel sedimentation downstream of Xiangjiaba Reservoir in 2020.
万方数据
维普
