黄河游荡河段河床形态调整对洪水过程的响应

以黄河流域1950～1985年200余场洪水资料为基础，并增加了最近的实验资料，分析了黄河下游游荡河段不同含沙量沙水过程中河床形态的调整过程，结果表明，由洪水过程所导致的河床形态变化是相当剧烈的。且与含沙量密切相关，表现出非线性的变化规律，当含沙量较小时，随含沙量的增大，洪水后河床宽深比增大，当含沙量增大到一定程度后再增大时，宽深比随含沙量的增大而减小，这一结果为修正Schumm关于河床形态变化的定性预测关系提供了新的依据。

The Response of the Channel Form Adjustment at the Wandering-braided Reaches of the lower Yellow River to Flood Events

Based on data from over 200 flood events covering a wide range of sediment concentration of the lower Yellow River from 1950 to 1985 and recent experimental data, this paper reveals the complex response of channel transverse adjustment at the wandering-braided reaches of the lower Yellow River to flood events with different sediment concentrations. The results show that the flood events can induce large extent of channel transverse deformation. And flood events with different sediment concentrations have different behaviors of fill-scour and ways of channel adjustment. The variations of the channel cross-section are firmly related to and exhibit complex relationships with the variations of sediment concentrations of flood events. When the sediment concentration of the flood events is low, the width to depth ratio of the channel will increase with it and when it increases to a certain degree to the range of hyper-concentrated flow, the width to depth ratio will decrease with the increase of sediment concentration. The channel metamorphosis controlled by channel fill and scour behavior is largely affected by the situations whether flood overflows floodplain or not. The over floodplain floods often carry heavy sediment load and cause the flow scouring in main channel and the sediment depositing on floodplain in large quantities, and as a result, the shallow and deep channel is formed. From the above results, the qualitative prediction relationships of river metamorphosis of Schumm's could be modified.