Risk Assessment And Control Of Collapse Disaster In Weining Tuohai Small Watershed Scale

Due to the complex and changeable of geological conditions and geographical environment in southwest China,geological disasters occur frequently.With the development of domestic economy,and human activities gradually intensified,Mudslides and other geological disasters will threaten the property and life safety of local residents once encountered external inducing factors such as heavy rainfall,earthquake,collapse and landslide.Therefore,the risk assessment of geological hazards is an important task for disaster prevention and reduction in the region.Taking Guizhou weining map new township drag the small watershed as an example,based on the special project-"Guizhou province key geological disaster risk assessment and control demonstration" of Guizhou province,the data are collected,combined with high resolution remote sensing image to drag the collapse of the river basin on remote sensing,the spot investigation and its results validation.The risk assessment of collapse disaster in a small watershed is carried out by combining GIS technology with mathematical statistics.On the basis of regional risk assessment,typical monomers are selected for risk assessment and reasonable control measures are proposed.This paper studies the risk assessment and control of the collapse disaster in the small watershed of towing the sea,with the purpose of providing references for the local disaster prevention and reduction.The main conclusions are as follows:1.The distribution characteristics of the collapse disaster body and the bearing carrier in the small watershed are analyzedThe collapse disaster bodies,houses,roads and land use types in the small watershed of towing sea were interpreted by high-precision remote sensing,and the results were verified by field investigation,so as to establish the geological disaster and bearing carrier database in the research area.2.Risk assessment of small watershed collapse disaster(1)According to the geological environment characteristics and field investigation in the study area,environmental factors(slope,relative elevation,fault,stratigraphic lithology)and trigger factors(rainfall,distance from rivers,and human activities)were selected as evaluation factors.Firstly,a layer of evaluation factors was established in GIS,and then the weight of factors was obtained according to the analytic hierarchy process.Finally,an evaluation map of collapse risk in the study area was generated.(2)According to the natural environment and economic development characteristics,Vulnerability assessment in the studied area from four aspects—building density,population density,road density and land use,building bearing vulnerability assessment model in the study area for pulling the collapse body in the sea of small watershed in quantitative assessment of vulnerability.(3)The risk assessment of the collapse disaster in small watershed is based on the probability of the collapse disaster and the losses caused.An evaluation model is built based on the collapse disaster risk assessment results and vulnerability assessment results in small watershed,and the spatial superposition calculation is carried out in GIS to obtain the collapse disaster risk result chart.The study areas were divided into four grades and their proportions were as follows: high risk area 1.14%,middle risk area 58.52%,low risk area 40.04% and very low risk area 0.3%.3.Risk assessment of single dangerous rock massFour single dangerous rock masses in high risk area were selected according to the results of collapse risk assessment in small watershed,that is,fanjiayan dangerous rock mass,fazer dangerous rock mass,leju dangerous rock mass and xinkaiping dangerous rock mass.Firstly,the characteristics and failure mechanism of the dangerous rock mass are studied.Then,according to the effects of topographic relief,vegetation coverage and stratigraphic lithology on rolling stone,a three-dimensional and two-dimensional model chart of falling stone trajectory was established,and the scope of the danger zone was divided according to the simulation results of the implementation trajectory.Finally,quantitative risk assessment is carried out for the dangerous area and reasonable risk control measures are proposed.