Characteristic And Risk Assessment Of Geological Disaster In Yijun County

Yijun county is located in Tongchuan City,Shaanxi Province,and in the Loess Plateau of Northern Shaanxi Province.In recent years,with the development of economy and the continuous improvement of urbanization,a large number of engineering activities cause damage to the local environment,coupled with the impact of extreme rainfall weather,resulting in frequent geological disasters,hindering social progress.How to solve the problem of harmonious coexistence between human and nature and the realization of sustainable development of mountainous cities and towns has become a key issue in today's society,which also makes the research on the characteristics and risk assessment of geological disasters in the study area of great significance.Based on the full collection of geological environment and social economic data of Yijun County,combined with field investigation and previous research results,this paper analyzes and summarizes the development characteristics,distribution rules and formation conditions of geological disasters in the study area.At the same time,based on Max Ent model,comprehensive fuzzy evaluation method and Arc GIS software,the risk,vulnerability and risk assessment of geological disasters are carried out.The main innovative achievements are as follows:(1)In Yijun County,there are 137 geological disasters,including landslide,collapse,unstable slope and ground collapse.Most of them occur in the rainy season and the period of intense human activities,and they are distributed along the river system in the narrow and long valley of the loess hilly area.Landform and rock and soil types are the original conditions that determine the development of geological disasters in the study area,while concentrated rainfall and large-scale human activities are the main inducing factors.(2)The evaluation index system of geological hazard risk is established by selecting disaster point factors and 9 environmental factors represented by elevation.By introducing the concept of maximum entropy and using Max Ent model to complete the probability prediction of risk distribution,the risk of geological disasters in Yijun county is divided into five levels: high,high,medium,low and low.(3)Five socio-economic factors such as population density were selected to establish the vulnerability evaluation index system of geological disasters.Based on the idea of fuzzy mathematics,the vulnerability evaluation calculation of the study area is completed by using the fuzzy comprehensive evaluation method,and the vulnerability of geological disasters in the study area is divided into five grades: high,high,medium,low and low.(4)According to the evaluation model of "risk = risk × vulnerability",with the help of Arc GIS software grid calculator function superposition and multiplication of risk and vulnerability evaluation results,the geological disaster risk evaluation of the study area is completed.According to statistics,the proportion of each risk area in the whole county is 6.71% in high risk area,8.06% in high risk area,19.63% in medium risk area,33.98% in low risk area and 31.62% in low risk area.The results show that the spatial distribution of geological disaster risk in Yijun county is high in the northwest and low in the southeast,and the overall risk of geological disaster is medium and low.According to the different risk levels,corresponding measures should be taken to prevent and reduce disasters,so as to realize the harmonious development of human,society,nature,economy and other elements in the study area.