Role of friction terms in two-dimensional modelling of dense snow avalanches

Abstract. Voellmy–Salm friction model is one of the most extensively used theories for assessing the frictional terms of the equations that describe the motion of non-Newtonian flows such as snow avalanches. Based on the Coulomb- and turbulent-type friction, this model has been implemented in numerical tools for computation of snow avalanche dynamics based on the Shallow Water Equations (SWE). The range of the Voellmy parameters has been discussed widely, focusing mainly on the required values for achieving good results for the description of the moment and position of the avalanche when it stops. However, effects of parameters on the SWE terms, and their physical interpretation have not been investigated sufficiently. This work focuses on analysing the effects of the Voellmy–Salm parameters and cohesion on the avalanche characteristics and evolution of the new SWE-based numerical model Iber. In the numerical scheme, an upwind discretization was used for the solid friction and cohesion terms, while a centred one was used for the turbulent friction. Results show that the Voellmy–Salm model dominates the avalanche dynamics and the cohesion model allows the representation of long tails, whereas the friction and cohesion parameters may vary within a wide range.