| Xingzhou Sub-district of Lueyang County has high mountains and narrow valleys,concentrated rainwater,strong tectonic activities,and fragile geological environment.In this paper,taking Xingzhou Sub-district as the research area,using remote sensing interpretation and on-site investigation methods,on the basis of analyzing the geological environment and the overall characteristics of geological hazards,two types of slope units are selected,and the Pearson correlation coefficient method and the information gain rate are used to determine the Evaluation index system;based on single model(random forest model,rotating forest model and AdaBoost model)and coupled models(information value-random forest model,information value-rotating forest model and information value-AdaBoost model),the landslide risk in the study area was evaluated.Evaluation and calculation of the daily rainfall early warning value under extreme rainfall conditions;The analytic hierarchy process was used to evaluate the vulnerability,and combined with the results of the hazard risk evaluation to complete the risk evaluation.The main findings are as follows:(1)On the basis of analyzing the developmental characteristics and distribution law of landslides in the study area,two typical landslides were selected,and the basic characteristics and influencing factors were mainly analyzed.The landslides in the area are mostly caused by human engineering activities and rainfall damage to their structure and mechanical characteristics.(2)The development characteristics of landslides in the study area were comprehensively analyzed,and each evaluation factor layer of two different slope units was obtained based on the grid layer;ten factors including aspect,slope,lithology,distance from water system,distance from road system,topographic wetness index,land use type,NDVI,and distance from structure system,rainfall were selected to construct the final landslide risk evaluation index in the study area.The frequency ratio method was used to analyze the spatial distribution characteristics of landslides in the study area.the favorable strata for landslides are sheet-like softer phyllite,layered hard igneous rock and layered hard slate;the slope range is 20°～35°,the south and southwest slopes,the topographic wetness index is in the range of 5～10,the rainfall is in the range of 800～850mm,the closer it is to the water system,the road,and the structure,the lower the vegetation coverage,the more prone to landslides.(3)The information value method was used for rapid modeling,and the non-landslide points equal to the landslide points were selected from the non-landslide area to form a model training sample;based on two different slope units,a single model and a coupled model are established to evaluate the landslide risk in the study area;the ROC curve and Kappa coefficient were used to test evaluation results;the information value-random forest model based on the curvature watershed method showed the best prediction effect,and its low,medium,high and very high risk areas accounted for 23.1%,27.6%,24.5%and 24.8%;based on the historical daily rainfall data,the Pearson-III function was used to calculate the daily rainfall data of different rainfall return periods,and the landslide risk zoning maps under different rainfall return periods in the study area were obtained.(4)More than 80%of the total area of the study area is classified as low-medium vulnerability.High-very high vulnerability areas are mainly concentrated in administrative villages such as Tongxin Village and Wujiaying Village;high-very high risk areas are mainly concentrated along the Jialing River,near main roads,Tongxin Village,Masangping Village,Lingyansi Village and Guandishan Village,landslide monitoring should be strengthened in these areas to avoid human and economic losses.The research results have certain reference value and significance for the prevention and mitigation of disaster of construction,urban planning and other projects of Xingzhou Subdistrict of Lueyang County. |
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