三峡水库蓄水前后宜都弯道河道演变特性分析

Analysis of River Channel Evolution Characteristics of the Yidu Bend before and after Three Gorges Reservoir Impoundment

为研究宜都弯道在三峡水库蓄水前后的河道演变特征,采用1970~2021年实测的地形资料,分析了宜都弯道岸线、深槽、深泓、横断面和冲淤变化特性,结合弯道水流运动特性进一步分析了河道演变的机理。分析结果表明:与一般弯道“凹冲凸淤”的规律不同,宜都弯道主要冲刷部位为弯道上游马家溪边滩和下游曾家溪边滩,马家溪边滩冲刷时期集中在三峡水库蓄水前的汛期,曾家溪边滩在三峡水库蓄水前后持续受到冲刷,汛期和枯水期均有发生。

In order to study the river channel evolution characteristics of the Yidu Bend before and after the im-pounded water in the Three Gorges Reservoir, the landform data measured from 1970 to 2021 were used to analyze the change characteristics of water front, deep groove, thalweg, cross section, erosion and siltation of the Yidu bend, and the mechanism of river channel evolution was further analyzed combined with the flow movement characteristics of the bend, which is different from the rule of “erosion of concave banks and siltation of convex banks” in general bend. The analysis results show that the main scouring sites of the Yidu bend are Majia Stream side beach on the upstream of the bend and Zengjia Stream side beach on the downstream of the bend. The scouring period of Majia Stream side beach is concentrated in flood season before the impoundment of the Three Gorges Reservoir, and Zengjia Stream side beach continues to be scoured before and after the impoundment of the Three Gorges Reservoir, both in flood season and dry season.