Study On Risk Assessment Of Geological Disasters In Zhidan County And Important Towns

In recent years,with the expansion of human engineering activities in Yan'an,the northern part of Shaanxi,the threats to people's lives and property and social economies caused by geological disasters have increased greatly.In order to lower the losses caused by the geological disasters,it becomes particularly important to propose effective governance measures and carry out risk assessment of geological disaster areas.As a geological disaster prediction and evaluation method,geological disaster risk assessment is considering from multiple perspectives,such as the slope,slope direction,elevation,economy,population loss,etc.,to comprehensively conclude the geological disaster risk assessment,which is beneficial for making preventive and protective measures before the occurrence of geological disasters.In this paper,taking Zhidan County and its surrounding important towns as the research object,in which the geological disaster risk assessment is carried out.The research area is the loess gully area,after the intensive human engineering activities,most of the slope stability has been severely damaged.Based on the investigation of geological disasters in the geological disaster risk assessment area of the study,the main research results are as follows:(1)Investigating the type and number of geological disasters in the research area,study and analyze its development characteristics,deformation modes and distribution characteristics.The research shows that: the geological disasters in the research area are mostly caused by deformation of slope structure and mechanical characteristics that have been caused by human engineering activities and the continuous rainfall.Rainfall is one of the important factors that affect the occurrence of geological disasters in the study area.In this paper,the risk of geological disasters are evaluated under the condition of extreme rainfall.(2)Carrying out the evaluation on the geological hazard in the research area based on the GIS research platform and logistic regression model,extract the influencing factors for evaluating the geological disasters,such as the slope,aspect,elevation,rainfall,stratigraphic lithology,water system buffer zone,and road buffer zone.Determine the high-risk area,higher-risk area,medium-risk area,lower-risk area,and low-risk area and its respective cover area in the research area.(3)Using UAV aerial survey to delineate slope unit,and determine the slope unit influence scope one by one,calculate the number of people and properties within the area.Based on the risk analysis of geological disasters in the study area,the vulnerability assessment factors are selected as population density,proportion of affected population,density of cultivated land,density of highway,per capita annual income of farmers,and density of buildings,and stablished fuzzy evaluation model to complete the vulnerability assessment of slope unit.Based on the results of risk and vulnerability assessment,the risk assessment of geological disasters in the area is carried out by using the quantitative methods.