Spatial Characteristics And Sensitivity Evaluation Study Of Collapse,Landslide And Debris Flow Potential Point In Karst Area

The hidden geological hazard is heterogeneous and unstable geological environment in Karst mountain and hilly area,with certain disaster conditions,the geological disasters can be induced,which pose a serious threat to people's lives,property and living environment,and restrict the sustainable development of society and economy.Qianxinan Prefecture is located in the Nanpan River orogenic zone,terrigenous clastic rock and carbonate rock mosaic,fully developed folds,faults,poor rock mass integrity,weak stability,and hidden geological hazard distributed over a broad area,which is one of the major prevention area in Guizhou province,also it's a typical study region for geological hazard point distribution analysis and sensitivity evaluation.In order to explore spatial pattern of hidden geological hazard point development and its sensitivity characteristics,this study took collapse,landslide and debris flow in Qianxinan prefecture as an example,used the weighted information value model to analysis the spatial characteristics of various types of hazards(including disaster points)and it's quantity and spatial correlation with hydrology,topography and climate rock characteristics,land cover,human disturbance factors,at the same time,evaluated and zoned the sensitivity of hidden points and control recommendations were put forward to reduce the pipe sensitivity of hidden disaster points,and draw the following important conclusions:1.Structure and distribution characteristics of collapse,landslide and debris flow hidden points(1)In terms of structure,the geological hazard potential points in Qianxinan prefecture was consisted of most landslides and some collapses,debris flows.and their number were 579,338 and 21 respectively,and accounting for total hidden points were 61.73%,36.03% and 2.24%.From the point of various potential points structure,the landslide potential points including landslide disaster potential(513 points),unstable slope(40 points)and potential landslide(23 points);landslide hazard points were mainly constituted by the landslide hazard point(147 points)andunstable rock mass(180 points);debris flow hazards were mainly composed of debris flow disaster points(19 points).(2)In terms of geographical distribution,landslide hidden points shown the common features of agglomerate and dispersive type in Qianxinan prefecture.The maximum hidden point density area was located in Longguang Town in Anlong county,its value reached 0.678count/km2,followed by was,Luojiang Town in Xingyi City,Longshan Town in Anlong county,and Changliu Town in Qinglong County,other area was small,which most of area was below 0.3/km2.In addition,the distribution characteristics of landslide potential points with feature of aggregated distribution,and collapse potential points are characterized by centralized and decentralized distribution.debris flow potential points are scattered mainly.2.Statistics and GIS spatial analysis method was applied in distribution statistics of landslide,collapse and debris flow disasters with their number,diversity and main affecting factors and quantitative screening,which aimed to reveal the relationship between spatial distribution and influence factors' in Qianxinan prefecture.Analysis shown that:(1)The surface roughness and the types of land use and construction land from 3 factors,the key factors affecting the development of the landslide disaster point slipstream.The collapse point is mainly distributed in the surface in the 1.063~1.138 forest and grassland area,landslide and debris flow hazard point distribution to the surface fluctuation in 1~1.062 between forest and grassland area,three kinds of geological hazards are all concentrated in the land and the construction of distance in the range of 1000~10000,showed that the disaster with strong spatial selectivity.(2)There is a nonlinear correlation between the hazard point and the environmental factor,and the spatial correlation has the factor interval selectivity.Taking the correlation between slope and hidden danger point as an example,the correlation between the number of landslide hazard points and the slope is satisfied with a single factor two regression model: Y_collapse =-0.03x2+1.907x-8.711(R2=0.742).The hidden danger of landslide meets the one element three regression model: Y_,slip =-0.004x3+0.256x2-3.171x+7.955(R2=0.918).3.After evaluation factors were determined,according to the natural breakpoint method and previous research results,the evaluation factors were classified.Then,used the analytic hierarchy process(AHP)to construct the weighted information model,the sensitivity of geological hazards potential points in the study area was divided.In the sensitivity level,severe sensitive area was 5956km2,which potential points density was 0.08 /km2,it was the largest area and density in the study area,and extremely sensitive area only 1349km2,but the corresponding point density was 0.07 /km2,in addition,insensitive and light sensitive area were the lowest density area(0.02/km2).4.According to the distribution characteristics in different sensitive areas,from the view of sensitivity control,the comprehensive strategy including : carry out geological environment survey and disaster monitoring;sensitivity and division of potential points of geological hazard evaluation;reasonable layout the production and living facilities and risk governance.In order to cut down the sensitivity of geological hazard potential points,reduce the occurrence of geological disasters,and provide reference for the prevention and control of geological disasters.