The Risk Evaluation On The Geological Hazards In Beichuanyi Autonomous County

The ecological environment of Beichuan Yi Autonomous County is fragile and geological disasters occur frequently.As one of the hardest hit areas of the Wenchuan earthquake in 2008,the earthquake triggered 596 geological disasters with varying scales in Beichuan County.The main types of disasters were landslides,mudslides,collapses,and dammed lakes,which caused the lives and property of residents in Beichuan County.Serious damage.On July 8-12,2013,there was continuous heavy rain in Beichuan County,and 802 new geological disaster points were added in the county.Frequent geological disasters seriously threaten the lives and property of local residents and restrict the long-term development of the local economy.Therefore,the risk assessment of geological disasters in Beichuan County is of great practical significance for maintaining the safety of local people's lives and property and promoting the sustainable development of the local economy.In this study,first based on the geological disaster census data that affected the Beichuan County settlement after the flood in 2013,comprehensive selection of natural factors such as topography,climate factors,land use types,etc,application of Geographical Detector Method for factor detection and quantitative attribution of geological hazards in Beichuan County.Secondly,the risk assessment and zoning of geological disasters in Beichuan County is carried out through the “risk= hazard? vulnerability” evaluation system,the main work includes the risk assessment and zoning of geological hazards,vulnerability assessment and zoning,risk assessment and zoning.The research results obtained in this paper are as follows:(1)Geological hazard impact factor detection,Among the single-factor detection results,the precipitation factor has the greatest influence.Factor detection by geo-detector,simultaneous and quantitative analysis of the spatial distribution and impact factors of geological disasters,screening 12 evaluation factors for risk assessment of geological disasters,the p value of the garden land and other land in the land use factor exceeds the limit value,explain that the spatial differentiation of gardens,other land uses and geological disasters is poor,therefore,gardens and other land use cannot be studied as impact factors.Through interactive detection of geo-detectors,the influence of the interaction between factors on the geological disasters in Beichuan County is higher than the influence of single factors on the geological disasters in Beichuan County,the main interaction types are two-factor enhancement and nonlinear enhancement.There are interactions between factors,and the interaction is enhanced,which provides the basis for factor selection and research for geological disaster risk assessment.(2)Geological hazard risk and vulnerability assessment,By constructing a weighted linear combination operator(WLC)method,the zoning map of geological disaster susceptibility evaluation in Beichuan County is obtained.The results were low-prone areas,medium-low-prone areas,medium-prone areas,medium-high-prone areas,and high-prone areas,accounting for 4.44%,13.61%,29.97%,31.32%,and 20.75%,respectively.Spatially superimposed risk level on the basis of the susceptibility zone,and obtained the zoning map of the geological disaster risk assessment of Beichuan County.The results were divided into low-risk area,medium-low-risk area,medium-risk area,medium-high-risk area and high-risk area,accounting for 20.87%,24.74%,34.89%,15.51%,and 3.99%,respectively.Using fuzzy comprehensive evaluation method to obtain the zoning of geological disaster vulnerability assessment in Beichuan County.The results are divided into low-vulnerable area,medium-low-vulnerable area,medium-vulnerable area,medium-high-vulnerable area and high-vulnerable area,accounting for 31.32%,7.25%,19.32%,5.92%,36.19%.respectively.(3)Geological disaster risk assessment,Multiply the risk assessment map and the vulnerability assessment map to obtain the risk assessment map of Beichuan County.The results were divided into low-risk zone,medium-low-risk zone,medium-risk zone,medium-high-risk zone and high-risk zone,accounting for 25.65%,17.86%,28.57%,18.71% and 9.22% of the total area respectively.The medium-risk area has the largest area.the population,roads and cultivated land in this area are concentrated and the vulnerability is high,but the risk of geological disasters is medium,so the overall risk is moderate.The high-risk area has the smallest area,mainly distributed in Yuli Township,Qushan Town and Tongkou Town.these areas have high population,road and cultivated land density,high vulnerability and high risk of geological disasters,so the risk of geological disasters is high.