三峡坝下游河道造床流量与水流挟沙力的变化

Variation of Dominant Discharge and Sediment-carrying Capacity of Flow in the Downstream of Three Gorges Reservoir

通过对三峡水库蓄水前后坝下游水沙条件代表站——宜昌水文站的资料进行统计,分析了三峡水库蓄水前后坝下游河道造床流量的变化,并结合水力学计算对水流挟沙能力进行估算,简要分析了坝下游河道水流挟沙能力沿程的变化情况。分析认为:三峡水库蓄水后引起的坝下游第一、第二造床流量变化和水流挟沙能力变化反映了坝下游河床以纵向冲刷为主的发展趋势;三峡蓄水前后同流量级条件下沿程水流挟沙能力的变化反映了三峡蓄水以来坝下游河段以中低水冲刷为主、中枯水位下降相对明显及河床沿程变化受节点控制的客观事实。

We analyzed the variation of dominant discharge and sediment-carrying capacity of flow in the downstream of Three Gorges Reservoir before and after the reservoir impoundment.The analysis is mainly based on data observed from Yichang hydrological station,the representative station in the downstream of the dam.We found that the variations of the primary and secondary dominant discharges caused by water storage of the Reservoir as well as the variations of sediment carrying capacity revealed the trend of longitudinal erosion of the riverbed.Moreover,variation of sediment-carrying capacity before and after the impoundment in the presence of equal flow explained the facts of medium and low flow erosion,medium and low water level,as well as the riverbed variation controlled by nodes.