HAZARD ASSESSMENT OF DEBRIS FLOW ALONG ZIRE-BOMI SECTION OF SICHUAN-TIBET RAILWAY

Debris flow is one of the most developed disaster types in the Tibetan Plateau, and poses a certain threat to the construction of Sichuan-Tibet Railway and the safety of life and property due to its sudden outbreak, violent movement process, and strong destructive characteristics. Geological hazard assessment is part of the effective measures in the management and prevention of disaster prevention and mitigation. For reasonably quantifying the spatial distribution characteristics of debris flow hazard along the railway line, the paper takes the Zire-Bomi section of the Sichuan-Tibet Railway within Linzhi City as the experimental area. We apply the Bayesian optimization algorithm based random forest(TBOR) and gradient boosting tree model(TBOG)to quantify the debris flow hazard values of the route section and identify the hazard levels. The input information of the two models includes 172 historical hazard points and 11 feature parameters. The output information is the outbreak probability of debris flow for each prediction unit. Lastly, the ROC-AUC method is employed to test the evaluation outcomes of the two prediction algorithms. The findings reveal that in the TBOR and TBOG models, the overall debris flow hazard level of the Zire-Bomi line section of the Sichuan-Tibet Railway is relatively high. The proportion of hazard zones inside the high-higher hazard interval of the two models reaches 56.439% and 66.580% respectively, corresponding to the highest hazard point densities of 12.577/(10²km²) and 12.940/(10²km²)respectively. Compared to the ROC-AUC values derived from the TBOG model, the TBOR model computes 0.89, which is higher than that of TBOR at 0.83. Therefore, the TBOR model has better prediction accuracy. The research findings can provide necessary reference for the construction of disaster prevention and mitigation protection projects along Sichuan-Tibet Railway and the hazard evaluation of other line sections.