When analyzing the runout process of debris flows using depth-averaged models, adopting generalized discharge hydrographs as input conditions is an efficient simulation method. Currently, generalized discharge hydrographs for debris flows are mainly categorized into triangular discharge hydrographs and pentagonal discharge hydrographs(Takahashi 1991). Although these methods have been widely applied in engineering practice, their applicability remains unclear(Guo et al. 2025). Therefore, based on the depth-averaged models, we perform simulation analysis on the motion characteristics of large-watershed and small-watershed debris flows under different generalized discharge hydrographs. By comparing simulated parameters such as flow depth, flow velocity, deposition range, and deposition volume, the applicability and rationality of different generalized debris flow discharge hydrographs in numerical simulations are investigated. Simulation results based on the Jiwozi debris flow (small-watershed) and Yuzhong debris flow (large-watershed) indicate that: generalized triangular discharge hydrographs are more suitable for small-watershed debris flows, better characterizing the rapid convergence characteristics of debris flows; generalized pentagonal discharge hydrographs are more suitable for large-watershed debris flows, better reflecting the characteristics of long initial convergence time and rapid subsequent flow changes. This study aims to provide a scientific basis for the reasonable selection of generalized debris flow discharge hydrographs, thereby offering reliable data support for the prediction and prevention of debris flow disasters.
 

Discharge hydrograph,debris flow,average-depth model,Runout simulation,Disaster prevention