Risk Assessment And Scenario Simulation Of Mountain Flood Disaster In Zizhou County

Because of the special climatic and geographical characteristics in the loess plateau,the flash flood,which is prone to take place in the flood season of summer,causes a serious damage to the mode of production and life of people,and restricts the sustainable development.Based on the research area of Zizhou County in Yulin city of Shaanxi Province and the detailed collection of the natural geospatial data,social economic attributes and the historical flash flood events.This paper starts with the trigger factors,environment factors of the underlying surface and the social economical vulnerability,which may affect the formation of the flash flood disasters,and then build the risk evaluation index system of mountain flood disasters by selecting 11 factors in total.Based on ArcGIS software for data processing and spatial analysis,finally the results of risk grade distribution of the flash flood disasters in Zizhou county are obtained.Then using P-Ⅲ distribution curve to simulate the precipitation in different recurrence periods,and the surface runoff is simulated by SCS-CN model,the results are used to simulate the inundation of the study area under different recurrence periods and finally combined with results of the risk assessment,zoning the flash floods prevention,putting forward the suggestions of flood control and disaster reduction,And taking the county area as an example,then proposing the super standard scheme for flood defensing.The conclusions are mainly obtained in the following areas(1)The results of mountain flood disaster risk assessment indicate,the high-risk areas and higher-risk areas of the flash flood disasters are concentrated in some areas in northeast and south,such as Dali river,Tuoerxiang ditch,Chabagou river,Huaining drainage basin.From the township perspective,Shuanghuyu,Miaojiaping,Matigou,Sanchuankou and Tuoerxiang towns are seriously threatened by flash flood(2)The results of the inundation simulation in study area shows that,the large areas of the formed town in Miaojiaping,Shuanghuyu and Huainingwan are submerged,when the raim of once-in-20-year occurred.And the larger areas of Peijiawan and Matigou town are submerged,when the rain of once-in-a-century occurred.(3)Demarcation of the mountain flood prevention zone,the results of the division is the towns,which has a high-risk of inundation and a large area that locates in high-risk regions,such as Miaojiaping,Matigou Shuanghuyu and Huainingwan town,are classified into.Sanchuankou,Peijiawan,Tuoerxiang,Dianshi,Zhoujian are divided into the sub-optimal control zones,other townships are belonging to the final control zone.(4)For the measures of flood control and disaster reduction,it is suggested that primary control zones should be given the priority to the dyke building,whose standards of construction are suitable for once-in-30-year,and for townships in sub-optimal control zones constructing the embankment is based on a standard for once-in-20-year.For the county areas,the watercourses should be cleaned in time,and enlarging the flood flowing zone and constructing the rescue channels,in order to cope with the ultra-standard floods.Evaluation of the current situation of mountain flood disasters,simultaneous division of mountain flood disaster prevention and control zones and put forward measures for flood control and disaster mitigation in Zizhou County can provide certain decision-making basis for local mountain flood disaster management,flood control decision-making and rescue and assist,and can also provide some reference for flood control and disaster reduction in the similar type of area,at the same time achieve the purpose of reducing disaster losses.