A comparison of avalanche models with data from dry-snow avalanches at Ryggfonn, Norway

Twelve well-documented dry-snow avalanches from the instrumented Ryggfonn path in western Nor-way were selected for back-calculations with several dynamical avalanche models. In each case, the run-out distance, the front velocity in the lower track, the extent of the deposits and the depth profile along a line are known. A 16 m high and 100 m wide retention dam in the run-out zone is often overflowed by avalanches but retains a considerable fraction of their mass. The tested models comprise a quasi-analytic block model, two I D hydraulic models, a particle model with entrainment, and SAMOS, an advanced 2D/3D two-layer model. For each model, a wide range of friction parameters was needed to reproduce the twelve events, and none of the models matches the deposit distributions of all avalanches with fair accuracy. Explicit representation of the intermediate-density layer in dry-snow avalanches and accurate numerical schemes are expected to improve the modelling of dam interactions.