Assessment Of The Geological Risk Based On GIS Of Fangshan District In The Beijing Municipal

Fangshan District is located in the southwest of Beijing,and it is located in the east and south of the north section of Taihang Mountain.Mountains and hills account for 2/3 of the whole region,and geological disasters occur with high frequency and large scale,which seriously threaten safety of lives and properties of local people.Scientific and reasonable geological hazard assessment is of great significance to the prevention and control regional disasters.Based on field survey and data collection,this paper taking 810 sites of geological disasters in Fangshan District as the research object.This paper summarizes and analyzes geological environment background,geological disasters and other related conditions of Fangshan District according to field investigation and data collection,so as to obtain the factors that affect the occurrence of geological hazards and their main development characteristics.The risk assessment of geological disasters in Fangshan District was completed by using GIS software,combining with the catastrophe progression theory and fuzzy comprehensive evaluation theory.According to the evaluation results,the corresponding geological disaster prevention measures are put forward.The main research contents and results of this paper are as follows:(1)Taking the natural geological environment conditions of Fangshan District as research background,the development characteristics,forming conditions,influencing factors and engineering geological conditions of geological disasters such as collapse and landslide are analyzed and concluded.(2)The risk assessment system of geological hazards in Fangshan District is established by selected eight indexes,including disaster site density,soil type,geological structure,topographic slope,vegetation cover,precipitation,engineering activities and river density.By using abrupt progression method,the weight of each evaluation index is calculated.GIS software is used for superposition calculation,and the risk is classified into three grades: high,medium and low,by which a map of the hazard of geological disasters in Fangshan District was obtained.(3)Population density,cultivated land density,road density and GDP density are selected for vulnerability evaluation.Streets and towns are taken as evaluation units,and fuzzy comprehensive evaluation theory and GIS software are used.Streets and towns in Fangshan District are divided into three grades: high,middle and low,by which a map of the vulnerability of geological disasters in Fangshan District is obtained.(4)Based on the evaluation results of the risk and vulnerability in this paper,the Risk(R)=Hazard(H)*vulnerability(V)calculation model is used,combinning with GIS calculation and analysis function,the risk of geological hazards in Fangshan District is classified into three grades: high,medium and low,by which a risk map of the geological disasters in Fangshan District is obtained.(5)Based on the results of risk evaluation,Fangshan District is divided into three zones,which are key,sub-key and general prevention and control zones,and different prevention and control measures are proposed for different risk zones.