基于洪水涨冲落淤特性分析游荡性河道双岸整治对冲淤的影响

基于黄河下游及主要干支流、美国密苏里河和密西西比河的实测资料,分析了低含沙洪水和高含沙洪水的输沙与冲淤特性。研究表明,河道沿程比降虽然变缓,但河宽变窄,流速沿程增加,是造成冲积河流保持洪水输沙平衡的边界条件。底沙的运动比洪水波传播得慢,是造成洪水在河道中长距离冲刷的根本原因,而与河道的比降陡缓关系不大。河道输沙特性呈现"多来多排",是形成河床沿程冲刷的水流动力条件。通过黄河下游河道双岸整治,河道形成窄深、归顺、稳定的河槽,使洪水造床和输沙作用增强,从而对河道冲刷作用增加。

Influences of regulation by two banks on the wandering Reach of Lower Yellow River based on scouring and deposition during flood processes

Based on field data,characteristics of sediment transport and scour in the Lower Yellow River and its main tributaries,the Missouri River and the Mississippi River are analyzed.The Characteristics of sediment transport,scouring and deposition of low-sediment concentration floods and hyper-concentrated floods are as follows:although the slope becomes mild along the river,the width becomes narrow and flow velocity increa ses,which creates the boundary condition of flood and sediment balance in alluvial rivers.The bottom sediment movement is slower than that of the flood wave.This is the fundamental reason for the long-distance scour in the river channel,which is not related with the gradient of the river.Characteristics of sediment transport can be described as "more sediment supply,more sediment being transported",which is the hydrodynamic condition of scouring along the river bed.Through the regulation of both banks of the lower Yellow River,a narrow,straight and stable river channel can be formed.The role of flood for bed-forming and sediment transport will be strengthened,as well as increasing its function of bed erosion.