摘要
雅安市地处四川盆地西缘与青藏高原的过渡地带,地形切割强烈,地质构造复杂,受"5·12"汶川地震和"4·20"芦山地震影响下,区内地质灾害频发.本文以雅安市作为研究对象,通过野外地质灾害调查和室内分析研究,开展了市域范围的地质灾害风险现状评价及预测评估.查清了研究区的地质环境条件和地质灾害类型、分布与规模,研究区内共发现地质灾害3846处,以滑坡、崩塌和泥石流为主;基于现场调查,选取坡度、流域平均坡度、工程地质岩组、斜坡结构类型、断层密度、剖面曲率、距道路距离、流域高差、主沟纵坡降、沟壑密度等因子,基于层次分析法-信息量模型对研究区各类型地质灾害易发性进行评价;结合易发性、危险性和易损性结果,运用ArcGIS对研究区地质灾害进行风险性综合评价和分区,预测了可能诱发或加剧的地质灾害危险性.结果表明:研究区可划分为低风险区、中风险区、高风险区和极高风险区4个等级,分别占研究区面积的89.27％、10.23％、0.49％、0.01％.研究成果可为区域性地质灾害风险评价提供方法借鉴,也可为雅安市防灾减灾及地质灾害风险管控提供参考.
Abstract
Ya'an City is located on the transition zone between the Sichuan Basin's western edge and the Tibetan Plateau.The geological structure of the study area is complicated. Under the influence of the"5·12"Wenchuan Earthquake and the"4·20"Lushan Earthquake,geological hazards occurred frequently in the study area.This paper evaluates the current situation and predicts the risk of geological hazards in Ya'an City through field investigation and analysis.The geological environment with types,distribution and scale of geological hazards in the study area were identified.A total of 3846 geological hazards were identified in the study area,mainly landslide,collapse and debris flow.Based on the field investigation,slope,watershed average slope,stratum lithology,slope structure,fault density,plane curvature,distance from road,watershed elevation difference,gully longitudinal gradient,gully density was selected as evaluation factors.The susceptibility of each type of geological hazard in the study area was evaluated by AHP-information coupling model.Based on the results of susceptibility,hazard and vulnerability,ArcGIS was used to evaluate and classify the risk of geological hazards in the study area.The potential or intensified geological hazard risk in the study area was predicted.The results show that the study area can be divided into four classes:low-risk zone,medium-risk zone,high-risk zone and very high-risk zone,respectively accounting for 89.27％,10.23％,0.49％ and 0.01％ of the study area.The research results can provide methods for regional geohazard risk evaluation and reference for geological hazard risk management in Ya'an City.
万方数据