Risk Assessment Of Geological Hazards In Pingshan County Based On GIS

Pingshan County is located in the foothills of Taihang Mountain in the west of Hebei Province.Affected by local geological environment,human engineering activities,rainfall and other factors,there are geological disasters such as collapses,landslides and mudslides in the study area.The existence of geological disasters restricts the social and economic development of Pingshan County.The risk assessment of geological disasters integrates the information of geological disasters and disaster-bearing bodies,and the evaluation results have reference value for the prevention and control of geological disasters in the study area and urban construction planning.This paper takes the geological disasters in Pingshan County as the research object.Based on the collection and sorting of regional geological data and geological disaster data,this paper organizes and analyzes the natural geography and geological environment of the study area,and influences the types,characteristics,distribution laws and influencing factors of the geological disasters in the study area.The analysis and summary are carried out;based on GIS technology,the geological disaster risk assessment is carried out using the information quantity model,the comprehensive index model and the analytic hierarchy-information model,and the influence of different models on the sensitivity of the evaluation index is analyzed and discussed,and three types of evaluations are made.The accuracy of the evaluation results of the model was verified and compared,and the evaluation results of the best evaluation model were selected as the final geological hazard risk evaluation results;the township was used as the evaluation unit,and the gray relational analysis method was proposed to analyze the risk of geological hazards in each town in the study area.Finally,based on the risk and vulnerability evaluation results,select the "R=H×V" risk evaluation model,and use GIS technology to conduct geological disaster risk evaluation and zoning.The main research content and results of the paper are as follows:(1)Select the slope,aspect,elevation,topographic undulation,landform type,rock group,distance to fracture,distance to river,NDVI,distance to road that characterizes human engineering activity factors,and annual average rainfall that characterize rainfall factors are selected to characterize geological environmental factors Measure these 11 evaluation indicators to establish a geological disaster risk evaluation index system in the study area,and use the information volume model,the comprehensive index model and the analytic hierarchy-information volume model for risk evaluation.The sensitivity analysis results of the evaluation indicators of that model are consistent.The ROC curve is used to verify and compare the evaluation results.Among the three models,the analytic hierarchy-information model has the highest evaluation result accuracy,with an AUC value of 0.821,indicating that the model can predict the geological hazard risk in the study area very well.The risk of geological disasters is divided into four levels: extremely high,high,medium and low.The extremely high-risk areas are distributed in the central,northern and southwestern parts of the mountainous area.The high-risk areas are mainly distributed in most areas of the western mountainous area,and the medium-risk areas are mainly Distributed in the eastern part of the study area,the low-risk area is mainly distributed in the central and eastern regions.(2)Three indicators of population density,building density and road density are selected to construct a vulnerability evaluation index system for geological disasters.Using townships as the evaluation unit,combined with GIS technology,a grey relational analysis method is proposed for the vulnerability of 23 townships in the study area.A classification evaluation was carried out,and the vulnerability of geological disasters in the study area was divided into four levels: extremely high,high,medium and low.Among them,the extremely high vulnerable areas were distributed in 3 towns in the east of the study area,and the high vulnerable areas were distributed in the study area.4 townships in the middle,middle vulnerable areas are located in the west and north of the study area 4 towns,low vulnerable areas are located in the southeast,southwest and northwest of the study area.(3)According to the results of the geological disaster risk and vulnerability evaluation in the study area,the risk evaluation model "R=H×V" is used to superimpose the risk,and the risk level judgment matrix is used to classify the risk evaluation results to obtain the geological hazard risk of the study area The zoning map divides the geological hazard risk of the study area into four levels: extremely high,high,medium and low risk.The extremely high risk areas are mainly distributed in the central part of the study area,and the high-risk areas are mainly distributed in the northern and central parts of the mountainous area.In the west and southwest,the medium-risk areas are mainly distributed in the northeast,southwest and Gangnan Reservoir of the mountainous areas and on both sides of the upstream water system.The low-risk areas are mainly distributed in the eastern part of the study area.