基于FloodArea模型的小流域山洪灾害临界雨量阈值初探

Research of the critical threshold of rainfall to flash flood in small basins based on Flood Area Model

针对缺乏水位流量资料的山区小流域地区山洪临界雨量难以确定的问题,以四川省南江河上游流域作为研究区域,基于德国Geomer公司开发的二维非恒定流水动力模型"FloodArea",利用流域逐时降雨资料,地形高程数据以及土地利用数据,重现南江"6·28"山洪暴发的动态演进过程,对模拟得到的逐时淹没深度与1~24 h累积流域面雨量求相关,选取预警点淹没深度与累积面雨量的相关系数最高的时效作为预警点致灾临界雨量阈值的预报时效,通过建立预警点淹没深度与预报时效累积面雨量的回归方程,从而获取预警点不同风险等级的临界雨量阈值。结果表明:FloodArea模型能够较好地呈现出此次典型山洪的暴发过程,通过对不同地势预警点临界雨量阈值的对比,最终选取地势较低,位于河流汇口地带、风险等级较高的上两九义校作为南江河上游流域山洪风险预警点。

The ＂6 ·28＂flash flood event in Nanjiang River,Sichuan,China,was examined through model simulation by using the tw o-dimensional hydrological dynamics model FloodArea,developed by Geomer GmbH,in combination with rainfall data,DEMand land utilization data. Based on the correlation betw een the simulated hourly water level and the accumulated area rainfall,choosing the given duration with the highest correlation coefficient as the threshold rainfall required to produce flash flooding in the study areas,guidance product of different pre-w arning flash flood can be obtained. Model analyses suggest that the simulated results of FloodArea fairly close to the actual flash flood process. Through the comparison and analysis of the threshold rainfall over different terrains,the Shangliang Jiuyixiao,w hich located at a confluence,is chosen to be the flash flood pre-w arning point of the Nanjiang River basin.