金沙江向家坝水电站下游河道2020年淤积成因分析  

Analysis of siltation causes in the downstream of Xiangjiaba Hydropower Station on Jinsha River in 2020

作　　者：杜泽东 秦蕾蕾 董先勇 DU Ze-dong;QIN Lei-lei;DONG Xian-yong(China Three Gorges Construction Engineering Corporation,Chengdu 610041,China)

机构地区：[1]中国三峡建工(集团)有限公司,四川成都610041

出　　处：《泥沙研究》2024年第1期45-50,共6页Journal of Sediment Research

基　　金：国家自然基金长江水科学研究联合基金项目(U2040217);中国水利水电科学研究院水利部水沙科学与江河治理重点实验室开放研究基金项目(Grant NO.IWHR-JH-2020-A-05)。

摘　　要：向家坝下游河道泥沙冲淤变化对岸坡稳定及通航具有重要影响,向家坝水电站运行后坝下游河床一直呈冲刷状态,但2020年首次出现淤积。采用输沙法和断面法计算向家坝出库沙量和下游河段泥沙冲淤量,结合气象、水动力及实勘资料,分析向家坝下游2020年淤积成因。研究结果表明:向家坝蓄水后出库年径流量变化不大,出库沙量受上游电站拦沙作用大幅减少,但2020年向家坝下游支流降雨偏丰,支流输沙量大幅增加,产生区域强输沙过程;该年下游各控制站最高水位较历史平均水位均偏高,汛期比降变化不大,水流挟沙能力不足以输送显著增多的泥沙;加上采砂减少和采砂造成的下切幅度较大部位发生回淤。这些原因导致2020年向家坝下游河道产生淤积。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 Station,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 downstream 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 capacity is insufficient to transport significantly increased sediment.In addition,with the reduction of sand mining,the sandpits with large downward cutting occurs re-silting.The above reasons cause channel sedimentation downstream of Xiangjiaba Reservoir in 2020.

关 键 词：向家坝水电站 泥沙冲淤 水面比降 水动力条件 河道采砂 

分 类 号：TV147.5[水利工程—水力学及河流动力学]