Simulating multi-phase erosive landslides with r.avaflow

Erosion often poses a great challenge in simulating hazardous multi-phase mass flows as it drastically changes the flow behaviour, impact force, run-out and deposition morphology by dramatically increasing their masses. Here, the comprehensive, unified mechanical erosion model for multi-phase mass flows (Pudasaini, 2025) is implemented for the first time in to the GIS-based open source computational tool r.avaflow. The model includes the frictional, collisional and viscous stresses. The consistent basal erosion rates for solid and fluid phases are based on the mechanically derived, dynamically flexible interacting stresses across the erosion-interface between the landslide and the bed. The model physically correctly includes the essentially composite erosion velocities of the mobilized particles and fluid from the bed and utilizes them to architect erosion-induced net momentum productions that consider all the interactions between solids and fluids in the landslide and the bed. This overcomes severe limitations inherited by existing erosion models. This mechanically-explained, comprehensive multi-phase model for erosive mass flows realistically embeds the erosion velocities, unified mechanical erosion rates and the net momentum productions into the mass and momentum balance equations. As the model makes a complete description of multi-phase erosive landslide dynamics by considering all essential aspects including the correct handling of inertia, the simulation results clearly demonstrate the physical essence of the new mechanical model substantiating the erosion-induced enhanced mass flow mobility with the net momentum production. This offers unique opportunities for practitioners in appropriately solving technical, engineering and geomorphological problems related to complex erosive multi-phase mass flows with r.avaflow.

Pudasaini, S. P. (2025). A comprehensive, unified mechanical erosion model for multi-phase mass flows. International Journal of Multiphase Flow, 191, 105328. https://doi.org/10.1016/j.ijmultiphaseflow.2025.105328