Modeling the influence of snowcover temperature and water content on wet snow avalanche runout

Abstract

Abstract. Snow avalanche motion is strongly dependent on the temperature and water content of the snowcover. In this paper we use a snowcover model, driven by measured meteorological data, to set the initial and boundary conditions for wet snow avalanche calculations. The snowcover model provides estimates of snow depth, density, temperature and liquid water content. This information is used to prescribe fracture heights and erosion depths for an avalanche dynamics model. We 5 compare simulated runout distances with observed avalanche deposition fields using a contingency table analysis. Our analysis of the simulations reveals a large variability in predicted runout for tracks with flat terraces and gradual slope transitions to the runout zone. Reliable estimates of avalanche mass (height and density) in the release and erosion zones is identified to be more important than an exact specification of temperature and water content. For wet snow avalanches, this implies that the 10 layers where meltwater accumulates in the release zone must be identified accurately as this defines the height of the fracture slab and therefore the release mass. This is an interesting result because it indicates the critical role of fracture depth as an input parameter in avalanche simulations. Advanced thermomechanical models appear to be better suited than existing guideline procedure to simulate wet snow avalanches when accurate snowcover information is available.

Simulation of cold powder avalanches considering daily snowpack and weather situations to enhance road safety

“…The remaining terms on the right-hand side account for the addition of heat energy from entrained snow and the fraction of heat energy produced during the plastic collision of the snowcover and finally the sensible heat exchange (q Φ→Λ ) of the flowing snow with the air. An additional mass balance equation accounts for the intake of bonded water in the snowcover and melting (Valero et al, 2017)…”

“…Consequently, the output from numerical models available to local hazard engineers for deciding whether to close a road is limited, as it becomes challenging to correlate specific measured data with potential avalanche run-outs. A first system using numerical simulations for road safety is implemented in Chile as described in (Valero et al, 2017). It uses avalanche dynamic modelling based on RAMMS to predict whether an avalanche reaches a road.…”