Study On Risk Assessment Of Geological Hazards In Loess Area Based On GIS

Zhongyang County is located in the middle of the Luliang Mountains.Quaternary loess is widely distributed in the territory,and geological disasters occur frequently,which restricts the local economic and social development.In order to reduce the property loss caused by geological disasters and the safety of people's lives,and to effectively control the geological disasters,the work of geological disaster risk assessment is particularly important.Taking Zhongyang County as the research object,this paper has ascertained the location,type,development characteristics and distribution rules of geological disasters,analyzed the disaster-generating geological conditions in the area,and carried out the risk,vulnerability and risk of geological disasters.Partition.The results obtained are as follows:(1)There are 86 geological disasters in Zhongyang County,18 landslides and 68collapses,which are mainly distributed in the loess hilly area in the north,west and southwest of Zhongyang County.According to field survey statistics,the types of collapses are:60 soil collapses,8 rock collapses;9 medium collapses,59 small collapses;53 tipping collapses,12 falling collapses,and 3 spalling collapses.The types of landslides are:5 traction landslides and 13 sliding landslides;4 medium-sized landslides and 14small landslides.(2)Geological disasters in Zhongyang County are group-occurring in time,generally concentrated in the rainy season each year;they are unevenly distributed in space,and there are more geological disasters in areas such as river valleys and landforms where populations live,and the county is southeast Because of the relatively small population density in the northern and southern bedrock areas,engineering activities are relatively weak,and geological disasters are relatively undeveloped.(3)The loess hilly areas with slope heights of 10-30m,slopes greater than 30°,and low vegetation coverage are areas of high incidence of geological disasters in Zhongyang County.The high and steep slopes formed by cutting slopes for building houses and cutting slopes for road construction are prone to geological disasters such as collapses and landslides under the conditions of rainfall,weathering and man-made disturbances.(4)This paper adopts three methods of analytic hierarchy process,information volume model and weighted information volume to evaluate the risk of geological hazards.Comparing the evaluation results,the weighted information volume model results are the best,and the weighted information volume model evaluation results are as follows:The area of extremely high risk area for geological hazards in Zhongyang County is about 29.11km~2,accounting for 2.02%of the county's total area,and 21geological disasters have developed;the area of high-risk areas is about 221.91 km~2,accounting for 15.40%of the county's total area,and is a geological disaster point.44places;the medium-risk area is about 383.98km~2,accounting for 26.64%of the county's total area,and 18 geological disasters are developed;the low-risk area is about806.40km~2,accounting for 55.95%of the county's total area,and there are 3 geological disasters.(5)This paper uses grey clustering theory to divide the vulnerability of geological disasters.The extremely vulnerable areas are Jinluo Town and Ningxiang Town,and the highly vulnerable area is Nuanquan Town.The areas with medium vulnerability are Zhike Town,Wujiazhuang Town,and Xiazaolin Township,and the area with low vulnerability is Chemingyu Township.(6)The geological disaster risk assessment result and the vulnerability assessment result are superimposed to obtain the geological disaster risk zone in Zhongyang County.The evaluation results are:the area of extremely high risk of geological disasters in Zhongyang County is about 15.51km~2,accounting for 1.08%of the county's total area;the high-risk area is about 249.04km~2,accounting for 17.28%of the county's total area,and the area of medium-risk areas.About 300.99km~2,accounting for 20.88%of the total area of the county;the low-risk area is about 875.86km~2,accounting for 60.76%of the total area of the district.