A Simple Deposition Model for Debris Flow Simulation Considering the Erosion-Entrainment-Deposition Process

This study aimed to determine the depositional effect and improve the identification of debris flow risk zones. To accomplish this goal, we developed a two-dimensional debris flow model (Deb2D) based on a hyperbolic conservation form of the mass and the momentum balance equation with consideration of the erosion-entrainment effect as well as the depositional effect. In this model, we implemented a widely-used rheological equation-the Voellmy equation-and a quadtree adaptive grid-based shallow-water equation. This model was applied to two study sites to assess the depositional effect. The impact area, volume of soil loss, maximum velocity, inundated depth, and erosion depth resulting from the debris-flow modeling were compared with the field data. The simulation results with/without deposition were evaluated using the receiver operating characteristic method. The implementation results of the erosion-entrainment model with deposition showed superior accuracy when estimating the damage range and flow time.