长江中下游设计洪水分析

Analysis of design flood in middle and lower reach of the Yangtze river

长江是一条雨洪河流,流域源远流长,大暴雨洪水时有发生。干流自宜昌出三峡后进入长江中下游平原水网区,河道穿行于广阔的冲积平原,水网交错、湖泊毗连,江湖关系复杂,两岸堤防高筑。遇大洪水时期,堤防的溃决或有意识的分蓄洪,以及江湖对洪水调蓄作用的变迁,致使中下游控制站实测洪水系列具有明显不一致性。在分析长江中下游洪水特性基础上,针对中下游河道行洪特征,采用总入流分析法,分析了中下游主要控制站设计洪水。经合理性分析表明,分析的总入流设计洪水成果可靠,能适应防洪规划的需要。

The Yangtze river is a storm flood river with a distant source and a long stream,and large storm floods occur occasionally in this river basin.The stem stream of the Yangtze river comes out of the Three Gorges reach at Yichang and then flows into the middle-lower plain and river-net area.The river runs in the vast alluvial plain with river nets crisscrossing and lakes standing next to each other.In the plain area,the relations between the river and lakes are very complicated and the river dikes are high on the river's two banks.For large floods,dike failure or purposeful flood diversion and storage as well as variations in flood-regulating function of rivers and lakes made flood series observed at control stations in the middle and lower area have obvious incompatibility.Based on analyzing the flood characteristics in the middle and lower Yangtze river,a total inflow analysis method is used to analyze the design floods at main control stations of the middle and lower Yangtze river.Analysis results show that design floods of total inflows obtained by analysis are reliable,and can meet the requirement of the flood control planning.