涉河工程影响下长江中游河道演变及水力特性变化研究

Study on river evolution and hydraulic characteristics of middle reaches of Yangtze River under influence of river related projects

三峡工程运行后,长江中下游河道发生了长距离、长历时的冲刷,河道水位及形态出现显著调整,对长江中游河床的影响最为明显。以三峡大坝下游宜昌至螺山站河段为研究区域,探究了长江中游河床冲淤、深泓变化、横向调整、床面糙率变化以及岸滩植被生长等在三峡水库运行前后的变化规律,并分析其与同流量下洪、中、枯水位变化之间的联系。结果表明:三峡水库蓄水后,河床横向形态变化有助于岸线的展宽;2001~2009年间河床糙率显著增加,并自2009年以来河段粗化作用基本完成;而河段沿程深泓变化则与相应的中、枯水位的变化规律一致。该研究成果可为长江中游河道治理、防洪规划及蓄滞洪区的利用等提供理论参考。

After the operation of Three Gorges Project,long-distance and long-term scour has taken place in the middle and lower reaches of Yangtze River,and the water level and shape of the river channel have been significantly adjusted,among which the influence on the riverbed of the middle and lower reaches of Yangtze River is the most obvious.Taking the reach from Yichang Station to Luoshan Station in the downstream of the Three Gorges Dam as the research area,this paper explored the changes of riverbed erosion and deposition,thalweg change,lateral adjustment,bed roughness change and beach vegetation growth in the middle reaches of Yangtze River before and after the operation of Three Gorges Reservoir,and analyzed the relationship between the above factors and the changes of flood,middle and low water levels under the same discharge.The results showed that after the impoundment of Three Gorges Reservoir,the transverse shape of the riverbed was conducive to the widening of the shoreline;the river bed roughness increased significantly from 2001 to 2009,and the river reach coarsening was basically completed since 2009.However,the change of thalweg along the river reach was consistent with the change of corresponding middle and low water levels.The research results can provide theoretical reference for river regulation,flood control planning and utilization of flood storage and detention areas in the middle reaches of Yangtze River.