| Tongchuan City is a traditional mining city in China.In recent years,excessive resource exploitation and frequent engineering activities have caused serious damage to the natural environment,coupled with more extreme weather such as heavy rainfall in recent years,geological disasters have occurred frequently,which not only threaten people’s lives and property,but also hinder the sustainable development of society.In order to reduce the losses caused by geological hazards and solve the problem of harmonious development between human and nature,it is especially important to carry out regional geological hazard risk evaluation.The risk evaluation study was carried out in Wang Yi and Yin Tai,two districts in the central part of Tongchuan City,which have a high distribution of geological hazards.The MaxEnt model and the AHP-entropy combination weighting method were used to evaluate the hazard,vulnerability and risk of geological hazards in the study area through field investigation:(1)Based on the field survey results of the project team,the distribution pattern,triggering factors and development characteristics of geological hazards in the study area were comprehensively analyzed and summarized.There are 102 geological hazards in the study area,including 44 landslides,21 cave-ins and 37 unstable slopes;the geological hazards are concentrated in the water system and both sides of the road in the study area,mostly occurring during the summer and autumn floods.Geomorphology and geotechnical type are the basic geological conditions for the occurrence of geological hazards,and precipitation and engineering activities are the main triggering factors for the occurrence of geological hazards.(2)Based on the basic characteristics of geological hazards and geological environment conditions in the study area,eight factors,namely elevation,slope,slope direction,rainfall,distance from road,distance from water system,geomorphology type and geotechnical body type,were selected to establish a geological hazard evaluation index system in the study area;the MaxEnt(maximum entropy)model was used to evaluate the hazard of geological hazards in the study area,and the results showed that the MaxEnt model AUC value is 0.942,and the accuracy of the model is very high;the contribution of eight environmental factors to the evaluation results is analyzed,and the results show that the type of landform and the distance from the water system are the factors with the greatest contribution;finally,the correlation between each factor and the hazard index is analyzed according to the response curve generated by the MaxEnt model.(3)Based on the social and economic development of the study area,four factors,namely,population density,GDP density,road density and arable land density,were selected to establish a vulnerability evaluation index system for the study area.The AHP-entropy combination weighting method was selected for the vulnerability evaluation.The AHP method calculated the subjective weights,the entropy method calculated the objective weights,and the combination weights were derived from the distance function to complete the vulnerability evaluation of the study area.(4)According to the"Risk=Hazard x Vulnerability"evaluation model,the risk evaluation results of the study area were obtained by multiplying the hazard and vulnerability results.The risk evaluation results of the study area were classified into 5 levels:high,mid-to-high,medium,min-to-low,and low:the risky areas from high to low were 3.48km~2(0.44%),14.02km~2(1.77%),68.73km~2(8.68%),117.51km~2(14.84%),and 588.10km~2(74.27%),and the overall riskiness of the study area was The overall riskiness of the study area is moderate to low,and the high-risk and higher-risk areas are concentrated in the central part of the study area in the more economically developed streets and part of Guangyang Town. |
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