Evaluating the thresholds for predicting post-earthquake debris flows: Comparison of meteorological, hydro-meteorological and critical discharge approaches

Post-earthquake debris flows pose significant hazards in mountainous regions following large seismic events. Evaluating the thresholds for predicting the occurrence of these flows is crucial. However, the absenting of comparison for different predicting methods hampers progress in improving and updating predictions for debris flows. In this study, based on on-site measurements of post-earthquake debris flows in an active catchment during the first year following the 2022 Luding Ms6.8 earthquake, 30 debris-flow events were identified and observed. We established and compared three distinct methods—namely, the meteorological approach, the hydro-meteorological approach, and the critical discharge approach for predicting the occurrence of post-earthquake debris flows. Additionally, we introduced a factor called absolute energy to improve the accuracy of the traditional meteorological approach. Absolute energy is defined as the sum of squared values within a time series. Our findings indicate that the hydro-meteorological model outperforms others in predicting post-earthquake debris flows, whereas the meteorological approaches especially the intensity–duration (I–D) thresholds exhibit suboptimal performance. Furthermore, the updated meteorological model incorporating absolute energy demonstrates improved predictive capability compared to traditional meteorological approaches like intensity–duration (I–D) thresholds. We argue that this comparative analysis will aid in selecting the suitable method for predicting post-earthquake debris flows.