考虑地貌差异的西南山区滑坡易发性评价研究

Assessing landslide-susceptibilities with consideration of geomorphic differences in southwest mountainous areas of China

  • 摘要: 西南山区地形复杂,滑坡频发.现有研究多聚焦单一地貌类型,缺乏不同地貌情景下模型适用性与主导因子差异的系统对比,且传统“黑箱”模型难以揭示地貌对滑坡主导因子的调控机制.本文以重庆城口县(深切山地)、梁平区(低山丘陵)和四川中江县(低丘平原)为研究区,构建机器学习-地貌分区-可解释性框架,利用随机森林(RF)、XGBoost和LightGBM算法评估滑坡易发性,并通过SHAP方法定量解析不同地貌下的因子贡献差异.结果表明,XGBoost模型具有较强的鲁棒性,在山地表现最佳(AUC = 0.923),丘陵和平原略低.地貌差异显著调控主导因子如下:城口县以高程和人类活动(POI核密度、距道路距离)为主;梁平区以岩性和粗糙度指数为主;中江县以降雨和高程为主.本研究验证了SHAP方法在解释“黑箱”模型方面的优势,从地貌差异视角揭示了滑坡发育的差异化驱动机制,为区域性滑坡精细化防灾提供科学依据.

     

    Abstract: The complex terrains in Southwest China often lead to frequent landslides. Past studies mostly focus on single geomorphic types, overlooking systematic comparison of model applicability and heterogeneity of dominant factors across different geomorphic scenarios.Traditional “black-box” models often struggle to reveal effects of geomorphology on landslides. In this study we establish a “Machine Learning-Geomorphic Zoning-Interpretability” framework for Chengkou county (mountainous), Liangping district (hilly), and Zhongjiang county (low hill-plain). Random forest (RF), XGBoost, and LightGBM algorithms were employed to assess landslide susceptibilities. SHAP method was used to quantitatively evaluate contributing factors under different geomorphic settings. XGBoost model demonstrated strong robustness, achieving best performance in mountainous areas (AUC = 0.923), but with slightly lower performance in hilly and plain areas. Geomorphic differences significantly modulated dominant factors. Landslides were found primarily driven by elevation and human activities (POI kernel density, distance to roads) in Chengkou. Lithology and roughness index dominated in Liangping. But rainfall and elevation were key factors in Zhongjiang. In this study we could verify the advantages of SHAP in breaking the “black box” nature of past models. We also elucidated differentiated driving mechanisms of landslide development from a geomorphic perspective. We therefore provide some solid scientific basis for refined disaster prevention in regional landslides.

     

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