台风暴雨影响区域的溃坝洪水演进数值计算

针对东南沿海受台风暴雨影响流域中下游地势较低洼开阔,在台风暴雨过程中容易积水,存在大面积初始水深,出现较严重内涝的特点,建立考虑下游区域初始内涝水深的二维溃坝洪水演进数值模型.基于数字高程模型(DEM)的地形数据和矩形网格,采用有限体积法和逼近黎曼格式及逆风守恒格式求解方程,并以戌浦江流域为典型,重点分析该流域存在内涝时上游水库发生溃坝的洪水演进特点.结果表明,溃坝洪水受下游初始淹没水深的顶托,下游区域的淹没水深并不是初始淹没水深和不考虑初始淹没水深溃坝计算所得水深的简单叠加,越往下游初始淹没水深对计算结果的影响越大;如果在计算中不考虑初始淹没水深,将会明显错误地估计洪水所带来的灾害风险.

Numerical simulation for dam-break flood in hurricane-prone regions

 The southeastern china is often attacked by hurricanes, in which most of basins have flat and depressed downstream areas. During the extremely heavy rainfall events, the downstream areas are often flooded. Once the dam failure takes place, dam break flood encountering the inland inundation existed in the downstream areas can greatly increase the loss and damage. A two dimensional numerical model was established to simulate the dam break flood, which considers the initial flood areas and initial water depth during the heavy storms. Based on DEM data and rectangular mesh, the governing equations were solved by finite volume method explicitly with the HLL approximate Riemann solver and upwind scheme. The established model was applied to simulate a dam break flood in a typical southeastern, Xupu Rriver basin,basin with the initial inundation water depth due to rainfall. The result shows that the simulated water depth of flood with the initial inland inundation being modeled can not be simply considered as the sum of initial inundation water depth and the water depth from the dam failure flood only. The impact of initial water depth on the computed water depth becomes significant when flood flow moves to the downstream area. Ignoring the initial water depth of inland inundation existed in the downstream area may inaccurately estimate the damage of the dam break flood．