Articles | Volume 8, issue 3
Model description paper
27 Mar 2015
Model description paper |  | 27 Mar 2015

EDDA 1.0: integrated simulation of debris flow erosion, deposition and property changes

H. X. Chen and L. M. Zhang

Abstract. Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA (Erosion–Deposition Debris flow Analysis), is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of the debris flow mixture determined at limit equilibrium using the Mohr–Coulomb equation is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, an adaptive time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional debris flow with constant properties and a two-dimensional dam-break water flow. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

Short summary
A new numerical model, EDDA, is developed for simulating debris-flow erosion, deposition, and associated changes in debris mass, properties, and topography. An adaptive time stepping algorithm is adopted to assure both numerical accuracy and computational efficiency. The performance of the model has been verified through four numerical tests and a large-scale case study. EDDA can be a powerful tool for debris-flow risk assessment in a large area and real-time landslide warning.