Calculating dense-snow avalanche runout using a Voellmy-fluid model with active/passive longitudinal straining

Abstract

A quasi-one-dimensional dense-snow avalanche model has been developed to predict avalanche runout and flow velocity in a general two-dimensional terrain. The model contains three different dense-snow-avalanche flow laws. These are: (1) a Voellmy-fluid flow law with longitudinal active/passive straining, (2) a Voellmy-fluid flow law advanced bv Russian researchers in which the Coulomb-like drv friction is limited bv a yield stress, a~d (3) a modified Criminale-Ericksen-Filby fluid m~del proposed by No;wegian researchers. The application of the Voellmy-fluid law with active/passive straining to solve practical avalanche-dynamics problems is evaluated by applying the model to simulate laboratory experiments and field case-studies. The model is additionally evaluated by comparing simulation results using the Russian and Norwegian models. In a final analysis the influence of the initial conditions on avalanche runout is investigated. vVeconclude that the model resolves many of the shortcomings of the Voellmy-Salm model, which is traditionally used in Switzerland to predict avalanche runout. Furthermore, sinee the model contains the three well-calibrated parameters of the Swiss Guidelines on avalanche calculation it can be readily applied in practice. vVediscuss why we believe the Russian and Norwegian models are not ready for practical application. Finally, we show that many problems remain, such as the specification of the initial release conditions. vVe conclude that numerical models require a more detailed description of initial fracture conditions.

A new method for avalanche hazard mapping using a combination of statistical and deterministic models

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“…They were gradually adapted to strongly timedependent flows such as waves induced by a dam break (Ritter 1892). A growing number of models based on the shallow-water equations are currently being used to describe natural flows such as flash floods (Hogg and Pritchard 2004), floods with sediment transport (Pritchard 2005), snow avalanches (Bartelt et al 1999), debris flows (Iverson 1997;Huang and García 1997), lava flows (Griffiths 2000), subaqueous avalanches (Parker et al 1986), and so on. In the derivation of these models, a number of assumptions are used, the most important of which are: the long-wave approximation (no significant curvature of the free surface), hydrostatic pressure, blunt velocity profile, and no change in the bulk composition or rheology.…”

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