多沙河流横断面调整及其对排洪和输沙能力的影响

多沙河流输沙能力的变化，突出地表现为河槽横断面的调整。黄河下游高含沙洪水过后，使游荡型河段河槽宽深比大幅度减少，从而提高了同流量的输沙能力，但因此使排洪能力大幅度下降。频繁出现的高含沙洪水异常高水位证明，断面缩窄比前期河床淤高对洪水位的影响更大。为了解决排洪与输沙的矛盾，建议排江与输沙分道，即尽可能地将高含沙水流徙用干流水库拦蓄，再用明渠向两岸高浓度输沙放淤，而河道只输送低含沙水流入海。

The Adjustment of Cross Sections in Over-loaded Rivers and its Influence on the Flood Delivery and Sediment Transporting Capacity

The sediment transporting capacity evolution of an overloaded river is evidently manifested in thechange of the cross section of the river channel. In the Yellow River, after a hyperconcentrated floodpassed, the ratio of width to depth of the channel is largely decreased in wandering reaches, and thereforethe sediment transporting capacity of same discharge is raised, and because of this the flood deliverycapacity is decreased in large extent. The fact of that there have been frequent abnormal high water levels inhrperconcentrated floods shown that the shrink of cross section influence the flood water level more thanthe before river bed silt does. In order to solve the contradiction between flood delivery and sedimenttransport, it is recommended that the flood delivery be seperated from sediment transporting in channels,i.e., to store hyperconcentrated flood as much as possible by reserviors in stem, then delivered tooutsides of both dykes by open channels to silt, and the river channel is only used for transporting the flow oflower sediment content into the sea.