一次特大暴雨诱发的山洪地质灾害淹没模拟分析

本文以四川省安县茶坪河流域2013年“7.9”特大暴雨过程为例,基于Flood Area模型模拟此次洪水的动态演进过程。通过对比5组不同试验结果,发现数字高程数据精度对模拟结果影响较大,采用经过填洼的DEM高程数据得到的模拟结果更为准确,粗糙度系数在取值范围内对模拟结果影响较小。模型最终采用经过填洼的DEM高程数据,反距离权重雨量栅格分布、泰森多边形计算的面雨量文件以及加入嵌入河道的粗糙度参数模拟茶坪河流域此次洪水过程,模型较好的模拟出了整个洪水的动态淹没过程。模拟结果与实地灾情对比:上游考察点附近河道最高淹没深度为5.8m,下游考察点最高淹没深度为3.83m,均与实际灾情较为吻合;对两个考察点逐小时淹没水深与1~8h累积面雨量求相关,得到上游千佛镇预警时效为2h,下游晓坝镇预警时效为6h。考察点位置不同,使得累积面雨量预警时效不同。 

A Simulation of Extreme Rainfall Caused Torrential Flood Inundation

The utilization of FloodArea model in torrential flood dynamic simulation is examined in this paper using the instance of an extreme rainfall process in Chaping River Basin, An county, Sichuan province, July 9th, 2013. The differences of5 model simulations indicate DEM (Digital Elevation Model) accuracy is an important influence factor in FloodArea model simulates. The simulations with filled DEM data are more accurate, the roughness coefficient within a specified range has little influences on simulations. The model simulations of Chaping River Basin torrential flood process in this paper use the filled DEM data, IDW (Inverse Distance Weighted) rainfall raster data, Voronoi diagram of rainfall distribution and the watercourse added roughness coefficients. The simulation results meet the actual torrential flood dynamic process. Compare to the real process, the upstream and downstream inundated depth are 5. 8m and 3. 83 m, meets the actual case. Through the correlation between hourly inundated depth and 1-8h accumulated rainfall distribution get the early warning time indices of two experimental points are 2h and 6h.