| Flash flood disaster has a relatively high probability of occurrence and poses a serious threat to local people's lives and property security in China mountainous areas,which is the primary problem in current disaster prevention and mitigation work and cannot be ignored.According to official statistics,Chinese annual flash flood disaster directly or indirectly led to the loss of people's lives and property accounts for about 40 percent of total loss caused by natural disasters.Chinese flash flood disaster presents a wide range of impact,high frequency of occurrence,short duration of disaster,large scale of damage and significant regional differences.Compared to the passive disaster relief,initiative to avoid disaster in the flood control and disaster mitigation engineering is more effective.The flash flood risk division can be a good reflection of this superiority of a flood control and non-engineering measures.As an important part of the flood control and disaster reduction system,the flash flood risk division provides scientific decision-making and effective hedging measures for the emergency command of the flood control department.It provides a reliable basis for the water conservancy department to scientifically determine the flood control standard and plan the flood control project construction,and provides important technical guidance and services of flood prevention and mitigation and emergency shelter for local urban expansion and construction,land use planning,production and operation of soho industry and residents life,which plays an important role in avoiding the losses caused by torrential disasters.Based on the natural environment background and humanistic environment background of the study area,this paper selects appropriate evaluation indicators from disaster factors,natural disaster index and body for disaster and builds the index system of regionalization in the study area.Then the following research work is mainly carried out:(1)Select surface elevation,slope,drainage density,monthly average rainfall during flood season,maximum rainfall in 24 hours and 6 hours,standard area flood peak flow as risk factors,then analysis the flash flood hazard to obtain the flash flood hazard map of research area.Get the distribution of the higher risk of flash flood disaster in the southwest of research area and the lower risk in the northeast and southeast regions.(2)Select population density,the percentage of arable land and road network as vulnerability factors,then analysis the flash flood vulnerability to obtain the flash flood vulnerability map of research area.The results show that the vulnerability of Daihai town,Maihutu town and Zhuozishan town is larger,however,the vulnerability of other regions is smaller.(3)The risk distribution map of the flood hazard and the vulnerability map are plotted in the ArcGIS to obtain the risk distribution map of the flash flood disaster in the study area.Then using the method of natural fracture,the risk level of the study area is divided into low risk,low risk,medium risk and high risk of four grades,get risk grade distribution map in the study.Finally,taking the township as the smallest research object,the author analyzes the risk zoning map according to the principle of zoning risk assessment.The relevant departments in Zhuozi County and Liangcheng County can carry out efficient,reasonable and targeted disaster reduction and disaster prevention work for the different risk levels of disaster area according the risk zoning and specific circumstances of each township level of risk.In the town of Manhan,Yongxing and Daihai,which are in high risk areas of flash flood disaster,some effective flood protection and mitigation measures can be carried out.For example,according to the local environmental conditions,it is necessary to plan the transfer route and resettlement of residents living in high-risk areas.Strengthen the provision of flood protection facilities such as flood protection dams to the larger population density of the high-risk areas. |
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