基于证据权模型的川西鲜水河断裂带滑坡易发性评价

Landslide Susceptibility Evaluation Based on Weight-of-Evidence Modeling in the Xianshuihe Fault Zone,East Tibetan Plateau

鲜水河断裂带是发育于青藏高原东缘的一条大型左旋走滑断裂带,该区新构造活动强烈且历史强震频发,一系列大型-巨型滑坡沿断裂带密集分布。在资料收集的基础上,对鲜水河断裂带两侧10 km区域内进行遥感解译和野外地质调查,建立数据库并对滑坡主要影响因素进行分析。在滑坡区域发育分布规律分析的基础上,选取地形坡度、地形坡向、地面高程、平面曲率、地形湿度指数、活动断裂、工程地质岩组、年降雨量、河流、道路、植被覆盖指数等11个因素作为滑坡易发性评价因子,在Arc GIS软件平台上,采用证据权模型开展了滑坡易发性评价。根据成功率曲线对评价结果的检验,滑坡易发性评价结果具有较好的精度,并将研究区的滑坡易发程度划分为极高易发、高易发、中等易发、低易发和不易发5个级别。滑坡的易发性受鲜水河断裂带影响显著,极高易发区和高易发区主要分布在东谷到道孚县沿鲜水河断裂带两侧,以及康定县城和磨西镇附近;中等易发区主要分布在鲜水河支流两岸及省道沿线;滑坡低易发区和不易发区主要分布在人类工程活动少的高山地带以及地形相对平缓的区域。滑坡易发性评价结果很好地反映了鲜水河断裂带区域内滑坡发育分布现状,为该区重大工程规划建设和防灾减灾提供参考依据。

Xianshuihe Fault zone is a sinistral-slip fault system on the eastern margin of the Tibetan Plateau with high Quaternary activity and frequently historic earthquakes. And large landslides are distributed along the fault zone. This paper investigated the landslide distribution characteristics in an approximately 7,339 km2 area and adopted Weight-of-Evidence Model （WOE） to develop landslide susceptibility evaluation. A detailed landslide inventory was prepared with a total of 415 landslides. Eleven landslide-causative factors were analyzed including slope angle, slope aspect, altitude, planform curvature, topographic wetness index （TWI）, active fault, lithology, annual rainfall, rivers, roads and the NDVI of the study area. Susceptibility mapping schemes with WOE model were put out in this study and the assessment result with ROC method showed that the WOE model had got well result responses. The landslide susceptibility in the study area is controlled by the activity of Xianshuihe Fault zone, and is divided into five levels including no susceptible, low susceptible, moderate susceptible, high susceptible and very high susceptible according to landslide susceptible degree. The areas with very high and high landslide susceptibility are mainly distributed on both sides of Xianshuihe Fault zone from Donggu to Daofu County as well as Kangding County and Moxi town nearby. The moderate susceptibility areas are mostly along the tributaries of the deepcutting valleys and the roads. Besides, the low and no susceptibility areas are mostly distributed on high mountain areas where human engineering activity is weak, as well as areas where is relatively flat. The evaluation results reflect that the current situation of geological disasters in Xianshuihe Fault zone is well. The result can be used for the planning of geological disaster prevention and the major construction in the region.