陆溪口鹅头分汊河段冲淤调整分析

Evolution of Goose-head Braided Channels in Luxikou Reach

陆溪口河段为长江中下游典型的鹅头分汊河段,三峡工程蓄水前,受进口单边挑流节点及弯道环流作用,河道演变呈现周期性演变规律;三峡工程蓄水后,在上游水沙条件变化、人为因素等影响下,河段冲淤规律将产生调整。采用理论分析、实测资料分析等方法,对蓄水后陆溪口河段周期性演变规律进行研究。分析表明:蓄水后河段周期性调整规律及趋势仍然存在,且由于上游来沙量减少,河段冲淤调整甚至有加快趋势;新洲洲头遭受严重冲刷,出现串沟,直港进口淤积严重,分流格局产生调整,航道条件变差。人为实施航道整治工程后,河势才有所稳定,但河段周期性演变的内在动力并未消失,对航道条件及整治工程带来了一定的不利影响。

Luxikou reach is a typical goose-head braided channel in the middle and lower reaches of Changjiang River. Before the impoundment of the Three Gorges Project,channel evolution shows periodic tendency due to flow deflecting caused by single-side node in inlet of channel and bend circulation effect. After the impoundment,the evolution regularity of scouring and silting changes under the influences of water and sediment in upper reach and human activities. According to theoretic analysis and measured data,we carry out research the periodic evolution of Luxikou goose-head braided reach. The results show that periodic evolution still exists,and adjustment of scouring and silting even speeds up due to the decrease of incoming sediment from upstream. Furthermore,the head of Xinzhou sandbar suffers severe erosion,and erosion ditch occurs. Meanwhile,sediment deposition is serious in the inlet of Zhigang,which leads to adjustment of flow distribution pattern and bad channel condition. After the implementation of artificial waterway engineering,the river regime gradually tends to be stable,but the inherent effect on cyclical evolution of river reach still exists,bringing out a negative effect on navigation conditions and regulation projects.