Analysis of service performance characteristics of debris flow check dams: A case study in Wudu District, Longnan City, Gansu Province

Check dams play a pivotal role in debris flow prevention and control engineering. However, their disaster prevention and mitigation capacity gradually decrease over service time due to repeated debris flow impacts. The study was carried out in 15 ditches and 55 check dams within Wudu District, Longnan City, Gansu Province. Seven key evaluation factors were selected for effectiveness and safety: reservoir siltation ratio, slope stability, drainage hole blockage, dam body damage, dam foundation damage, dam shoulder damage, and safety. The evaluation model of the serviceability of the indivusual dam and the comprehensive serviceability of the single trench of the barrage was established by using hierarchical analysis and fuzzy comprehensive evaluation method, and the serviceability was divided into four grades: excellent, good, medium and poor. The evaluation results show that the serviceability rating of individual dams is predominately "poor", accounting for 34.5%. Similarly, the collective serviceability rating of single trench dams for debris flow is predominately "poor", at 33.3%. The results of the evaluation are consistent with the fieldwork observations, providing a valuable reference for predicting the service performance and service life of barrage dams.