黄河下游河道萎缩模式研究

依据河工模型试验和原型定位观测资料分析，研究了黄河下游河道萎缩的基本模式及河道萎缩与水沙过程的跟随性。结果表明，河道萎缩模式主要有“滩槽并淤”和“集中淤槽”两大类，同时，还存在着“淤积不萎缩”的造床现象；对于某一变异水沙过程，河道萎缩具有“前置”性，而且，河道萎缩并不需要在很长的时期内才可完成，一个汛期内就可能发生明显萎缩；主河槽过流面积、主河槽河床平均高程是判别河道萎缩的必要因子，而断面宽深比不是必要因子。

Study on channel shrinkage mode in the lower Yellow River

According to the physical model test and the field data, the basic mode of channel shrinkage in the lower Yellow River and the response of channel shrinkage to the flow-sediment processes have been analyzed. The results show that channel shrinkage modes can be summarized as two main types, i.e. deposition occurs in both floodplain and main channel and deposition appears mainly in main channel. In addition, the bed-forming phenomenon of deposition without shrinkage is also observed. The results also indicate that the channel shrinkage can be finished in a short time and sometimes an obvious shrinkage could happen in only one flood season. It is suggested that the change of wetted-area and main channel bed elevation of a cross section are the two main factors to judge channel shrinkage, but the ratio of width to depth is not necessary.