A two-layer depth-averaged model for simulation of mixed snow avalanches

Mixed snow avalanches exhibit distinct flow regimes, including a frictional dense core at the base, a collisional fluidized layer above it, and a turbulent regime forming a powder snow cloud at the top. Despite its destructive potential, the powder snow cloud is occasionally implemented in numerical codes for snow avalanche hazard mapping. In collaboration with Dieter Issler (Norwegian Geotechnical Institute), we developed the numerical model MoT-PSA, which is based on the two-layer depth-averaged formulation developed by Eglit and co-workers in the 1980s. It has been extended to three-dimensional terrain and utilizes a fast numerical scheme based on the method of transport. Compared to previous works, we introduce novel formulations for the suspension of snow from the dense core and for deposition of the dense core. Physics-based models for snow cover entrainment and air entrainment are employed. In this presentation, I will discuss the underlying physical assumptions of the model and present its capabilities through the back-calculation of a mixed snow avalanche that occurred in Lom, Norway, in 2020.

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