| The Hengduan Mountains are a highly developed area for landslides and other geological hazards,and are one of the most severe geological hazard areas in China.The southern section of the Hengduan Mountains in Yunnan Province is the core area in the Hengduan Mountains that best represents its geomorphological characteristics.Based on the field survey data collection,the county-scale area in the southern section of the Hengduan Mountains was selected as the research object,and the research data were extracted and obtained based on GIS and ENVI software and remote sensing interpretation.The information database of landslide hazard points in the study area was established,and based on the GIS platform,the current development characteristics of landslides in the study area,disaster-preventing factors and distribution patterns were analyzed.Based on the analysis of historical landslides in the study area and the topographic and geological conditions of the study area,11 hazard evaluation factors such as elevation,slope,vegetation cover and rainfall and 4vulnerability evaluation factors such as population density and building density were selected to evaluate the landslide hazard and vulnerability of the study area,and finally coupled the hazard of natural attributes of landslides with the vulnerability of social attributes to evaluate the landslide risk.The ROC curve is used to verify the results,and the verification shows that the evaluation results are highly reliable and match with the actual disaster distribution,and the landslide risk evaluation system has certain applicability,scientificity and applicability.The main conclusions of the paper are as follows:(1)The analysis shows that the landslides in the region are mainly slope residual layer landslide,landslide landslide and artificial landfills landslide,and there are great differences in the topographic factors such as elevation,slope and structural plane development degree.In addition,in addition to the internal dynamic factors,landslide development is also significantly related to the external dynamics such as rainfall,vegetation development and human engineering activities,according to the analysis of the geographical characteristics of landslide points.(2)Combined with the analysis of the landslide database and the topographic features of the site,11 main control factors such as elevation,slope,slope direction and undulation were selected as the landslide inception factors in the study area,and the distribution of landslide development was analysed.The study shows that landslides in the study area are more developed in the elevation range of1623m～1910m,slope range >40°,northeast and south slope direction,softer rock layers and low vegetation cover areas,and show a trend that landslides develop closer to fracture zones,water systems and roads as the intensity of human engineering activities increases.(3)The Entropy Weighting Method(EWM),an objective assignment method,was used to calculate the weights of each evaluation factor,avoiding the influence of subjective factors on the weighting analysis.From the results,we know that vegetation cover,lithology of strata,elevation and distance from roads are the four most important factors affecting the occurrence of landslide hazards in the study area,illustrating the importance of these factors to landslide hazards in the Hengduan Mountains.(4)The EWM-IV coupled model was used to analyse the landslide hazard in the study area,and the hazard values of-0.7895～0.5602 were obtained.The natural interruption method was used to zone the landslide hazard in the study area in four classes.The AHP and comprehensive index models were used to analyse the vulnerability of the hazard-bearing bodies in the study area,and obtained vulnerability values from 1.000 to 4.000,and divided the area into four vulnerability classes,and finally coupled hazard and vulnerability to carry out quantitative analysis of landslide risk,and obtained risk values-2.2173<R<2.2265,and finally divided the risk into four classes: high risk(10.71%),higher risk(31.14%),medium risk(41.76%)and low risk(16.39%).The high risk and higher risk areas together accounted for 41.85%,indicating a high landslide risk in the study area.The ROC curve was used to test the EWM-IV model and the riskiness evaluation results,and the AUC value of hazard was0.862 and the AUC value of riskiness was 0.842,indicating that the evaluation results of this paper are highly reliable. |
