| Geological disaster is one of the main types of natural disasters in China,which has the characteristics of sudden,widespread and regional.In recent years,due to the frequent occurrence of global extreme weather,intensified plate tectonics activity and increased intensity of human activities,as well as the large number of mountains and complex and diverse geological structures in China,regional geological disasters have occurred frequently,posing major threats to the safety of people's lives and property,and seriously affecting social stability and sustainable development.Therefore,it has become an important work for China to improve the system and mechanism of preventing and defusing major risks and realize the modernization of national governance capacity and governance system to comprehensively grasp the hidden dangers of regional geological disasters,scientifically evaluate the risk level of geological disasters,and accurately grasp the current development stage and risk status of geological disasters.At the same time,it has also become an important manifestation of China's commitment to putting the people first,life first and ensuring the safety of people's lives in the new era.The Risk of geological disasters refers to the probability of geological disasters occurring in a certain area in a certain period of time and the degree of loss it will cause,which is usually expressed as "Risk = Hazard × Vulnerability".The risk assessment of geological hazards is a comprehensive assessment of the risk level of regional geological hazards,which includes two aspects: risk assessment and vulnerability assessment.Comprehensive geological hazard risk assessment is of great significance to comprehensively understand the overall risk level of regional geological hazard and the risk difference within the region,and to improve the comprehensive prevention and control ability of regional geological hazard.Therefore,this study is located in Daba Mountain foothill,complex geological structure,the relationship between man and vulnerable Chengkou typical mountainous area as the research object,based on "Chengkou 1:50000 geological disasters in Chongqing detailed refinement and regional geological disaster survey" project,based on positive and negative to DEM hydrological analysis method to extract the slope unit as the basic evaluation unit,establish Chengkou county geological disaster risk evaluation of spatial database,build the evaluation index system of geological hazards and the quantitative evaluation model,and separately in Chengkou county geological disaster risk assessment(H)and on the basis of vulnerability assessment(V),Based on the risk concept model(R=H×V),the risk level of geological hazards in Chengkou County was comprehensively evaluated,and the evaluation results were divided into regions.The main research results are as follows:(1)The spatial database of risk evaluation of geological hazards in Chengkou County has been established.This study based on "Chengkou 1:50000 geological disasters in Chongqing detailed refinement and regional geological disaster survey" project,through field investigations and remote sensing,field check methods of historical documents,a comprehensive grasp of Chengkou county geological disaster type,distribution,number,location and other geographic information,complete Chengkou county geological disaster spatial database was established.A total of 516 geological hazards were investigated,including 238 landslides,70 dangerous rocks,10 collapses,26 debris flows and 172 unstable slopes.(2)The risk evaluation index system of geological hazards in Chengkou County was constructed.This study combined with the regional characteristics of Chengkou county,elevation,gradient,slope direction,curvature,relief degree,engineering geological petrofabric,vegetation coverage,the distance from the river,distance from roads,land use type,soil type,the average annual rainfall and human engineering activities(mines density,the density of POI,slope point density)and other 15 risk assessment factor,and population density,road density,density of arable land,the density of GDP four vulnerability assessment factors,such as scientific Chengkou county geological disaster risk evaluation index system is constructed.(3)The risk assessment and zoning of geological hazards in Chengkou County have been carried out.According to the formation mechanism and development characteristics of the geological hazards in Chengkou county,this paper takes the slope unit as the basic evaluation unit and uses the weighted information model to evaluate the hazard of the geological hazards in Chengkou county.The results show that there is a large spatial difference in the level of geological hazard in Chengkou County,and the main disastercausing factors are different in different regions.The results show that the area of extremely high risk area in Chengkou County is relatively large,with a total area of637.82 km~2,accounting for 19.39% of the total area of Chengkou County.The area of high danger area is 847.81 km~2,the area of medium danger area is 953.13 km~2 and the area of low danger area is 850.32 km~2,accounting for 25.78%,28.98% and 25.85% of the total area of Chengkou County,respectively.(4)The vulnerability evaluation and zoning of geological hazards in Chengkou County have been carried out.According to the regional characteristics of population,economy,resources and environment in Chengkou county,the vulnerability of geological hazards in Chengkou county is evaluated by fuzzy comprehensive evaluation model,which also takes slope unit as the basic evaluation unit.It is found that the spatial difference of geological hazard vulnerability in Chengkou county is small,and the distribution of extremely vulnerable areas is relatively balanced on the whole,and presents a patchy distribution with the regional economic and social development layout.The area of extremely vulnerable area in Chengkou County is very small,88.18 km~2,accounting for 2.68% of the total area of Chengkou County.The middle vulnerable area has the largest area,which is 1342.43 km~2,accounting for 40.81% of the total area of Chengkou County.The area of high and low vulnerable areas is 1202.47 km~2 and 656.05km~2,accounting for 36.56% and 19.95% of the total area of Chengkou County respectively.(5)The risk level of geological disaster in chengkou county is evaluated comprehensively,and the prevention and control suggestions are put forward according to the results of zoning.Based on the results of risk assessment and vulnerability assessment of geological hazards in Chengkou County,the risk conceptual model(R=H×V)was adopted to comprehensively evaluate the risk level of geological hazards in Chengkou County.The results show that the risk level of geological hazards in Chengkou County has a large spatial difference,and the extremely high risk areas are obviously concentrated in the central and western regions and along the banks of Qianhe River,Renhe River and its tributaries.According to the zoning results,the extremely high risk area in Chengkou County contains 529 slope units with a large area of 773.05 km~2,accounting for 23.50% of the total area of Chengkou County,which needs to be monitored and prevented.The high risk area contains 602 slope units,with the largest area of 1060.63 km~2,accounting for 32.25% of the total area of Chengkou County.Monitoring and prevention should be strengthened.There are 505 slope units in the middle risk area,with a large area of 933.34 km~2,accounting for 28.35% of the total area of Chengkou County,which needs regular monitoring and prevention.The low-risk area contains 263 slope units,with a relatively small area of 522.12 km~2,accounting for 15.87%of the total area of Chengkou County,and it only needs daily monitoring and prevention. |
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