清水下泄条件下沙质弯曲河段滩槽演变规律分析

摘要

三峡蓄水后,库区泥沙落淤,清水下泄,对坝下河段滩槽格局产生一定影响.文章针对沙质弯曲河段,研究了三峡水库蓄水后河段的演变规律.按深泓平面变化特点,沙质弯道河段一般分为进口直线区、横向过渡区、弯顶区以及出口直线区.清水下泄条件下,进口和出口直线区河势总体变化不大,横向过渡区深泓由凸岸走向凹岸态势保持不变,但横向过渡区及弯顶区河势变化相对剧烈,突出表现为凸岸边滩冲刷,滩体根部窜沟发展,凹岸潜洲持续发育,深泓向凸岸侧摆动,断面向枯水双槽发展,导致弯道滩槽稳定性变差.%As the impoundment of the Three Gorges reservoir, sediment deposited in the reservoir and clear wa-ter was discharged in the downstream river. In this paper, typical reaches were chosen to study the effect of release of clear water on sandy bend reach evolution law. Sandy bend reach could be divided into four areas:inlet-straight line area, transverse transition area, bend vertex area and outlet-straight line area. Under release of clear water con-dition, inlet-straight line area and outlet-straight line area always keep stable. Talweg direction from convex bank to concave bank was not changed in transverse transition area. However, river regime in transverse transition area and bend vertex area changed dramatically, including beach eroding in convex bank, channeling groove developing in beach root, deep groove depositing in concave bank, talweg swing to convex bank, river section shape turning to dou-ble groove. The evolution had caused instable of sandy bend reach.