Debris flows account for a substantial economy and property loss in Western Ghats of Kerala, India, especially during monsoon seasons. Wayanad district is an active erosion zone in the plateau margins of Western Ghats, and there is a remarkable rise in the number of debris flows since 2018, due to very high-intensity rainfalls in this region. This study comprises geotechnical investigation, runout modeling, and calibration of friction parameters of Kurichermala debris flow, one of the devastating debris flow events that happened in Wayanad, during the 2018 monsoon. The detailed investigation and back analysis of such events are substantial in calibrating the flow parameters for the region. These parameters can be used for predicting the flow paths of possible debris flows and quantitative risk assessment in the future. The geotechnical investigation provided vital information regarding the soil type and shear strength parameters of the debris flow and has helped in understanding the flow behavior. A dynamic numerical model, rapid mass movements (RAMMS), was used for the back analysis of the debris flow, using the shape information of the flow. For precise calibration using statistical comparison, an image processing tool has been developed, to compare the structural similarity of simulated results with the original shape of debris flow. The dry-Coulomb friction coefficient (μ) was calibrated as 0.01 and turbulent friction coefficient (ξ) as 100 m/s2 for the event, using Voellmy-Salm rheology. The shape predicted by the model had a similarity index of 0.626 with the actual shape of debris flow. The results were found to be in accordance with the field and geotechnical observations. Hence, the results can be used to predict the shape of possible debris flows in the study area. The study is the first of its kind for the region and has significant influence in risk assessment for this highly susceptible landslide zone.

中文翻译：

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印度Kurichermala泥石流摩擦参数跳动建模与标定

在印度喀拉拉邦的西高止山脉，尤其是在季风季节，垃圾流造成了大量的经济和财产损失。瓦亚纳德地区是西高止山脉高原边缘的一个活跃侵蚀带，由于该地区的降雨强度非常高，自 2018 年以来泥石流数量显着增加。这项研究包括岩土工程调查、跳动建模和 Kurichermala 泥石流摩擦参数的校准，这是 2018 年季风期间发生在瓦亚纳德的破坏性泥石流事件之一。对此类事件的详细调查和反向分析对于校准该区域的流动参数具有重要意义。这些参数可用于预测未来可能发生的泥石流流动路径和定量风险评估。岩土工程调查提供了关于泥石流的土壤类型和剪切强度参数的重要信息，并有助于了解流动行为。一个动态数值模型，快速质量运动（RAMMS），被用于泥石流的反分析，使用流的形状信息。为了使用统计比较进行精确校准，开发了一种图像处理工具，将模拟结果的结构相似性与泥石流的原始形状进行比较。使用 Voellmy-Salm 流变学，干库仑摩擦系数 (μ) 校准为 0.01，湍流摩擦系数 (ξ) 校准为 100 m/s2。模型预测的形状与实际泥石流形状的相似指数为0.626。发现结果与现场和岩土工程观察一致。因此，该结果可用于预测研究区可能出现的泥石流形状。该研究在该地区尚属首次，对这一高度易感滑坡区的风险评估具有重大影响。