三峡下游沙卵石河段纵剖面形态对枯水位影响

Characteristics of channel profile and its impact on low flow water level in the gravel/sand bed reach downstream the Three Georges Project

采用近期河床地形及枯水位资料,分析计算了三峡下游沙卵石河段纵剖面形态对沿程枯水位的影响。结果表明:芦家河浅滩是河段内主要控制性河段,对抑制宜昌水位下降起着关键性的作用;下游枝江浅滩、江口浅滩对枝城以上河段枯水位直接控制作用甚小,但对芦家河以下的水面比降影响很大。在将来冲刷过程中,经过江口、枝江、芦家河三个控制性浅滩河段的缓冲作用,陈二口以上段的水位不致发生大的变化,但下游枝江、江口浅滩段水面陡坎可能加剧。

In the near-dam reach downstream the Three Georges Project（TGP）, the channel bed mainly consists of gravels, which controls its channel shape and magnitude. The hydraulic feature of the channel is to some extent controlled by the shape of channel profile. Based on the measured data, the present channel profile and its impacts on low flow water level are studied. The result shows that the Lujiahe shoaling reach, which is covered with gravel layer and has the highest thalweg elevation, plays an important role in controlling the lowering of the upstream water level during channel degradation. Zhijiang and Jiangkou shoals have a slight influence to the water level in the upper reach of Zhicheng, but a big influence to the water surface slope in the lower reach of Lujiahe. In the future erosion process due to the TGP operation, a notable change is unlikely to take place in the shoaling reaches of Jiangkou, Zhijiang and Lujiahe, so the low flow water level will change a little in the upper reach, but the sand bed erosion downstream of the study reach will probably make a big change of the water surface slope in the lower reach.