Research On Disaster Characteristics Anal Lysis And Susceptibility Zoning Of Landslides And Collapses In Luonan County,Shaanxi Province

Luonan County is located in the eastern section of the Qinling Mountains in the Qinba Mountains.It has diverse natural terrain conditions,complex geological structures,concentrated rainfall,and strong human engineering activities.It is one of the counties prone to geological disasters in Shaanxi Province.Landslides and collapses occur frequently in the study area,seriously threatening the lives and property of local residents."2018-2022 Shaanxi Province Geological Hazard Comprehensive Prevention System Construction Project"is the basis of this paper,taking Luonan County’s landslide and collapse disasters as the research object.Based on the county’s geological environmental conditions and field surveys,the development and distribution characteristics of landslides and collapse disasters in the study area Perform analysis.Using Arc Gis software as the analysis platform,spatial analysis of the selected eight main influencing factors is carried out,and the law of landslides and collapse disasters in Luonan County is summarized.Taking the grid unit and the slope unit as the basic evaluation unit,using the information amount-analytic hierarchy process evaluation model,the landslide and collapse in Luonan County are used to carry out the zoning study of the geological hazard susceptibility.In order to test the accuracy of the evaluation model,the evaluation results were compared and analyzed with the help of ROC curve.The main contents of the paper are as follows:(1)Through the field survey of geological disasters,109 hidden danger points of landslide and collapse disasters in Luonan County were classified and statistics,and the development,types and characteristics of landslide and collapse disasters were summarized;Mapgis software was used to draw the distribution map of landslide and collapse disasters.Analyzed the distribution characteristics of landslide and collapse disasters in the area from three aspects:administrative area,topography and geomorphology,and time of occurrence.(2)After fully understanding the development and distribution characteristics of landslides and collapses,select 8 major hazards such as elevation,aspect,slope,stratum lithology,average annual rainfall,fault distance,river distance,and highway distance.Using the spatial analysis function of Arc Gis software,combined with the relative density method,each type of factor is analyzed,the influence of each hazard factor on the landslide and collapse disaster is studied,and the law of landslide and collapse geological disaster in Luonan County is summarized.(3)Eight factors including elevation,aspect,and slope are used as evaluation factors,and based on the basic principles of analytic hierarchy process and information volume method,the comprehensive weight and information volume of the susceptibility of each evaluation factor are calculated.Through the information-level analysis evaluation model,grid unit and slope unit are used as the basic evaluation units to separately evaluate the susceptibility of landslide and collapse geological hazards in Luonan County.(4)Based on the basic principle of ROC curve,take the cumulative amount of landslide collapse susceptibility area ratio as the abscissa,and the cumulative amount of the percentage of landslide collapse disaster points as the ordinate.The accuracy of the susceptibility evaluation results were tested,and the AUC values were 0.70 and 0.74,respectively.It is concluded that the susceptibility evaluation effect with the slope unit as the evaluation unit is better.The susceptibility of landslide and collapse geological disasters in Luonan County is divided into high-prone areas(391.82km~2),medium-prone areas(851.10km~2)and low-prone areas(1588.18km~2).