考虑库水位及降雨联合作用的云阳县区域滑坡危险性评价

Assessment of Regional Landslide Hazard in Yunyang County Considering the Combined Effect of Reservoir Water Level and Rainfall

危险性评价是区域滑坡灾害风险评价及风险管控工作中的关键内容。以三峡库区重庆市云阳县为例,首先利用逐步判别法从初始指标体系中筛选关键指标体系(坡度、高程、剖面曲率、地形湿度指数、岩土体类型、植被覆盖度和距道路距离),并基于逻辑回归模型完成全区滑坡易发性区划;然后以距水系5 km范围将研究区划分为非库岸区和库岸区,对非库岸区考虑不同降雨重现期下的滑坡时间概率,对库岸区考虑不同库水位状态与不同降雨重现期下的滑坡时间概率;最后综合时间概率和易发性结果得到云阳县区域滑坡灾害危险性区划图。研究结果表明:区内滑坡主要发育在强降雨+低库水位状态工况下;云阳县滑坡较高危险区及高危险区占研究区总面积的52.7%,主要沿长江干流及其支流水系展布,分布在城镇周边等人类工程活动开发程度较大的建设用地区域。研究成果对于提高危险性评价结果的精度和发展滑坡灾害风险评价理论具有借鉴价值。

Hazard assessment is a key issue in risk assessment and risk control of regional landslide disaster.With Yunyang County,Chongqing City in the Three Gorges Reservoir area as study area,the stepwise discriminant method was employed to screen key indices(slope,elevation,profile curvature,terrain humidity index,rock and soil types,vegetation coverage and distance to roads)from the initial index system.The spatial probability of landslide was obtained by susceptibility zoning of the whole study area using logistic regression model.Furthermore,the study area was divided into non-reservoir-bank area(beyond 5 km to the water system)and reservoir bank area(within 5 km to the water system).For the time probability of landslide in non-reservoir-bank area,different return periods of rainfall was considered,while for the reservoir bank area,the combination of different reservoir water levels and different rainfall return periods was considered.According to the final comprehensive time probability and susceptibility results,the zoning map of regional landslide hazard risk in Yunyang County was obtained.Results suggest that landslides in the area mainly occur under the combined actions of heavy rainfall and low reservoir water level.Accounting for 52.7%of the total area of Yunyang County,areas of high risks distributed in construction land areas around cities and towns with intense human engineering activities along the main stream of the Yangtze River and its tributaries.The research findings offer reference for improving the accuracy of risk assessment and developing the theory of landslide hazard risk assessment.