基于HEC-RAS及HEC-GeoRAS的溃坝洪水分析

洪水漫顶、渗漏等原因引起的垮坝失事,将会给下游人民带来巨大的生命财产损失,因此,对溃坝洪水引起的淹没范围的准确预测至关重要。通过对大渡河上22座梯级水电站进行对比分析,选定长河坝电站水库大坝为研究对象,分析洪水漫顶引起的长河坝溃坝,及由其引起的下游黄金坪、泸定水电站的连续溃坝对泸定县的淹没范围。首先利用HEC-GeoRAS和Google地球提取研究区域的地形数据,然后将建好的模型导入到一维溃坝洪水计算工具HEC-RAS中进行溃坝洪水演进模拟,最后通过HEC-GeoRAS分析研究区域的洪水淹没范围及流速分布。结果表明:由长河坝溃坝引起的下游泸定县的洪水淹没范围为左右岸平均漫堤宽度约200 m,已经淹没到了城区;从流速分布图得出河道中心的流速均较大,最大流速为16.217 m/s。研究结果可为洪水风险图的制作及防洪决策提供一定的技术支持。

Analysis of dam-break flood based on HEC-RAS and HEC-GeoRAS

If the dam failure and break induced by overtopping flow and leakage through the dam, it will cause a great loss of life and property for the people downstream. Therefore, it is significant to predicate accurately the flooding area. By analysis of 22 hydropower stations located on the Dadu River, Changheba hydropower station was selected as a research object. The flooding area of Luding county caused by the overtopping floods of the Changheba hydropower station dam and its downstream Huangjinping dam and Luding dam was analyzed in this paper. Firstly, the terrain data was extracted by HEC-GeoRAS and Google Earth, after then, the data was imported into the HEC-RAS and dam-break flood was calculated. Finally, the flooding area map and flow velocity distribution map were captured using HEC-GeoRAS. The analysis results show that there is a flooding area of 200 m induced by overtopping along both left and right bank sides; the flow velocity along the center of the river is large and the maximum velocity can reach 16.217 m/s. The analysis results can provide a technical support for the production of a flood risk chart and for flood control decision.