基于数值模拟的群发性泥石流危险性评价——以甘肃岷县麻路河流域为例

Risk assessment of mass debris flow based on numerical simulation:An example from the Malu River basin in Min County

岷县是甘肃南部泥石流频发地区。岷县泥石流多分布于洮河干支流两岸,为群发性泥石流。为了研究群发性泥石流的运动及堆积特征,选取了甘肃岷县麻路河流域为研究区域,以流域内2012年"5·10"暴发泥石流造成重大损失的6条泥石流沟作为整体研究对象,并考虑主河对泥石流堆积物的冲刷携带,运用FLO-2D模拟降雨前主河流动情况及不同降雨频率条件下主河及泥石流的流动情况。根据野外调查结果对比2%降雨频率条件下泥石流模拟结果,验证模型的可靠性。基于模拟结果用ArcGIS进行危险性评价,识别流域内高危险泥石流沟并划定高危险居民区,统计受冲击范围,为泥石流防治和预警工作提供科学依据。

Min County is an area with frequent debris flow in the south part of Gansu Province.In order to study the movement and accumulation characteristics of debris flow,the Malu River basin in Min County,Gansu Province,which was affected by serious debris flow on May 10,2012,is selected as the research area.Six debris flow gullies in the basin are taken as the research object,which are taken as a whole.Considering the main river’s scouring and carrying of debris flow deposits,FLO-2 D is used to simulate the flow situation and different rainfall frequency of the main river before rainfall.According to the field investigation results,the debris flow simulation results under the condition of 2%rainfall frequency are compared to verify the accuracy of the model.Based on the simulation results,ArcGIS is used to carry out the risk assessment,identify the high-risk debris flow gully in the basin,delimit the high-risk residential area,and make statistics of the impacted area,so as to provide scientific basis for debris flow prevention and early warning.