Abstract The morphometric characteristics of a basin have a significant effect on landslide occurrence and can provide valuable information related to rainfall-induced shallow landslides. Basin morphometric parameters (e.g. average slope, relief and Melton ratio) can be correlated to landslide triggering factors such as rainfall intensity and duration. In this study, the physically-based model TRIGRS was used to determine rainfall intensity and duration (I-D) thresholds for shallow landslides in 93 small basins in the Colombian Andes. The results show highly variable thresholds, even for basins in the same region that are very close together. Different morphometric parameters were calculated for each basin and their effect on the threshold (power-law curves) characteristics was analysed. The morphometric parameters with greater effect on the threshold position (in the I-D graph) are mainly related to the slope gradient, but other elements (e.g. soil properties and basin area), that are important to consider in a physically-based methodology for defining rainfall thresholds, are also described. This analysis is useful for a better understanding of the factors affecting the threshold variability. It could be significant in the subsequent validation of rainfall thresholds defined using this methodology and its implementation in a landslide early warning system in areas for which landslide inventories are not available.

中文翻译：

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盆地形态参数对浅层滑坡物理降雨阈值的影响

摘要 流域地貌特征对滑坡的发生有重要影响，可为降雨诱发的浅层滑坡提供有价值的信息。盆地形态测量参数（例如平均坡度、地势和梅尔顿比率）可以与滑坡触发因素（例如降雨强度和持续时间）相关联。在这项研究中，基于物理的模型 TRIGRS 用于确定哥伦比亚安第斯山脉 93 个小盆地浅层滑坡的降雨强度和持续时间 (ID) 阈值。结果显示阈值变化很大，即使是同一地区非常靠近的盆地也是如此。为每个盆地计算了不同的形态测量参数，并分析了它们对阈值（幂律曲线）特征的影响。对阈值位置（在 ID 图中）影响较大的形态测量参数主要与坡度有关，但其他因素（例如土壤性质和盆地面积）在定义降雨量的物理方法中需要考虑阈值，也有描述。此分析有助于更好地了解影响阈值变异性的因素。这对于随后验证使用此方法定义的降雨阈值及其在滑坡预警系统中在滑坡清单不可用的地区的实施具有重要意义。还描述了在定义降雨阈值的基于物理的方法中需要考虑的重要因素。此分析有助于更好地了解影响阈值变异性的因素。这对于随后验证使用此方法定义的降雨阈值及其在滑坡预警系统中在滑坡清单不可用的地区的实施具有重要意义。还描述了在定义降雨阈值的基于物理的方法中需要考虑的重要因素。此分析有助于更好地了解影响阈值变异性的因素。这对于随后验证使用此方法定义的降雨阈值及其在滑坡预警系统中在滑坡清单不可用的地区的实施具有重要意义。