黄河下游河道对水沙过程变异响应

Response of the Channel to the Variation of Water and Sediment Processes in the Lower Yellow River

近年来黄河下游河道来水来沙量持续减少,河道演变特性发生变化,同时引起黄河下游河道的"小水大灾"、"横河"、"斜河"等问题。针对日趋严重的水灾问题,本文选取黄河下游典型站点分析黄河下游河道对水沙过程变异的响应,得到初步认识:一方面,由于黄河来水量减小,水流挟沙能力降低,致使黄河下游河槽持续淤积抬高、河槽变窄、河道过水断面变小,易引起"小水大灾";另一方面,由于来水来沙量变异,黄河漫滩概率减小,使黄河下游河型发生缓慢的改变,引起河势变化,原有的部分工程措施因水流流路的改变被迫废弃,甚至产生负作用,形成水灾。

With the continuous decrease of the incoming water and sediment, water disasters in the Lower Yellow River is becoming more and more serious, sueh as ＂serious disaster caused by small flood＂, ＂cross flow＂ and ＂gradient flow＂. To reveal the causes of these phenomena, an analysis on the responses of the channel to the variation of water and sediment processes in the Lower Yellow River is performed. The typical stations of Huanyuankou and Jiahetau in the Lower Yellow River are selected in the case study. The results show that as the amount of the water discharge and sediment in the Lower Yellow River decreases, the lower riverbed is deposited, the bed level rises, the channel becomes narrow, and the river pattern is changed. As a result, the risk of water disaster in the lower reaches increases. On the other hand, the changes of the river pattern lead to a failure of proper functions of some river engineering structures and even lead to negative functions of lhese structures, which could also be the cause of water disasters. The rules would be helpful for decision-making in the river, and the further study is necessary.