面向区域滑坡易发性精细化评价的改进斜坡单元法

Improved slope unit method for fine evaluation of regional landslide susceptibility

易发性评价是区域滑坡灾害风险预警与稳定性分析的基础,针对乡镇尺度的大比例尺精细化滑坡易发性评价,传统基于水文学和地貌学的斜坡单元划分方法难以满足评价精度。针对以上问题,以重庆市万州区大周镇为实例验证对象,形成了适用于精细化评价的改进斜坡单元划分方法。首先从斜坡地质环境孕灾规律出发,综合考虑地形地貌、物质组成、斜坡结构和灾害类型的均一性要求,提出了基于斜坡地质环境一致性的改进斜坡单元划分方法,选择重庆市万州区大周镇为实例验证对象,并与水文分析法、曲率分水岭法进行了对比分析。结果表明:(1)改进斜坡单元法划分的评价单元大小均匀性较好,未出现细碎单元或畸形长条状单元;(2)评价单元的总体形态特征更为合理,形态指数集中在1~2之间,呈现圆形或正方形斜坡形态;(3)改进斜坡单元划分的结果与已有灾害边界范围的叠加重合度最高,能更好地体现滑坡易发性评价或稳定性分析物理意义。研究结论对提高区域滑坡易发性评价的准确性与精度具有重要借鉴意义。

Susceptibility evaluation is the basis of regional landslide risk early warning and stability analysis.Scientific and reasonable division of evaluation unit is the key to landslide susceptibility evaluation.For large-scale fine landslide susceptibility evaluation,the traditional slope unit division method based on hydrology and geomorphology generally results in low accuracy of the evaluation.In this paper,an improved slope unit method based on the slope geological environment is proposed.Dazhou Town was selected as an example and the obtained results from the proposed model were compared with the results from hydrological analysis method and curvature watershed method.The results show that the size uniformity of the evaluation units divided by the proposed method is better,and no fine units or deformed long strip units were generated.The overall morphological characteristics of the evaluation unit are more reasonable,and the morphological index is between 1 and 2,which generally presents circular-like or square-like shape.At the same time,the superposition degree between the results of the improved slope unit division and the range of the existing disaster boundary is the highest,which can better reflect the physical significance of landslide risk assessment.The proposed model has significant potential for improving the accuracy of regional landslide susceptibility evaluation.