基于熵指数与随机森林模型的滑坡易发性评价

    Large-scale landslide susceptibility evaluation based on entropy index - random forest coupling model

    • 摘要: 机器学习广泛应用于区域滑坡易发性评价中。传统研究通常采用GIS随机生成的方法来获取安全点,但此类方法具有较大的随意性,使机器学习预测的结果精度不高,拟合性较差。此外之前的研究中区域面积选取得过小,致使降雨量在区域内差异不明显,导致训练对其不敏感,隐形地忽视了降雨量致灾因子。鉴于此,通过选取3.4万km~2的渝东北区域为研究区,引入熵指数(IOE)-随机森林(RF)耦合的评价模型。该模型通过客观计算每类影响因子的概率密度和熵权指数形成熵权表,进而生成滑坡易发性分区图,从低易发区中选取安全点,确保为非滑坡单元,降低了随机性的同时提升了合理性与准确性。将选取的安全点与该地区581个滑坡点作为训练集与选取的坡度、坡向、地形地貌、岩性、距公路距离、距河流距离、距断层距离、NDVI、降雨量共9项影响因子导入随机森林算法中,再基于GIS平台得到渝东北地区滑坡易发性分区图,实现对该地区的滑坡灾害易发性评价。结果表明:IOE-RF模型比单一RF模型精度提高约8%,证明IOE-RF模型可适用于渝东北或类似大面积研究区滑坡易发性评价;渝东北区域中东西走向的弧形大巴山冲断-褶皱带附近与其他特高风险地区在未来的防治工作中应该重点关注。研究结果可为当地滑坡灾害预防与治理提供辅助决策依据。

       

      Abstract: Machine learning is widely used in regional landslide susceptibility evaluation. Traditional studies usually use GIS random generation methods to obtain safety points, but such methods have a large arbitrary nature, which makes the machine learning prediction results less accurate and poorly fitted. In addition, the area selected in the previous study was too small, resulting in insignificant intra-regional variation of rainfall, which led to insensitivity of training and invisible neglect of rainfall-causing factors. In view of this, we select the 34 000 km2 northeast of Chongqing City as the study area and introduce an entropy index (IOE)-random forest (RF) coupled evaluation model. The model forms an entropy weight table by objectively calculating the probability density and entropy weight index of each type of influence factor, and then generates a landslide susceptibility zoning map. We select safety points from the low susceptibility area, ensuring they are non-landslide units, which reduces randomness while improves rationality and accuracy. The selected safety points and 581 landslide points in the region are used as training sets, and together with nine influence factors of slope angle, slope aspect, landform, lithology, distance from roads, distance from river, distance from fault, NDVI, and rainfall are imported into the random forest algorithm, so a landslide susceptibility zoning map is obtained by using the GIS platform, which realizes landslide hazard susceptibility assessment. The results show that the IOE-RF model is about 8% more accurate than the single RF model, which proves that the IOE-RF model can be applied to the evaluation of landslide susceptibility in Northeast of Chongqing City or similar large study areas; the east-west trending arc of the Daba Mountains near the alluvial-fold zone in Northeast of Chongqing City and other special high-risk areas should be focused on in the future prevention and control work. The results can provide an auxiliary decision-making basis for local landslide hazard prevention and management.

       

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