α - β model: Can we learn more from the statistical avalanche model with respect to the dynamical behavior of avalanches : Can we learn more from the statistical α - β model with respect to the dynamical behavior of avalanches? [Poster u.d.T.]

Birmensdorf

2009

S.405-408 + Poster

Artikel aus einer ZeitschriftBandaufführung

10536S

159584

A meaningful risk assessment in avalanche prone areas involves the estimation of the runout and impact pressures of potential avalanches. Two categorize of methods for determination of the runout exists. The first method is based on statistical methods such as the well known α - β model. The second is based on numerical avalanche models such as the PCM-model or Voellmy-Salm type models. More sophisticated models are based on similar rheological models. Dynamic models have the advantage that they, in addition to the estimated runout distance, also provide velocity and impact pressure distributions along the avalanche track. However, the success of the dynamical models depends on the knowledge of appropriate rheological models describing the behavior of flowing snow and their parameters. We re-evaluate avalanche data from Norway, Austria, and other parts of the world, on which the well-known statistical α - β model is based, with respect to dynamical measures. As all those avalanche data belong more or less to extreme events (i.e. avalanches with return periods of 30 - 300 years or more) the dynamical measures can give hints for an appropriate rheology for dynamical models suitable for extreme avalanche events. The analysis raises reasonable doubt whether the classical ansatz for the retarding acceleration with additive terms involving Coulomb-friction and a velocity squared dependency, which is used as basis in many avalanche models, is adequate.