Item: Dynamic Avalanche Modeling in Natural Terrain
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Title: Dynamic Avalanche Modeling in Natural Terrain
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors:
- J.T. Fischer [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ] [ Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn, Germany ]
- J. Kowalski [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- S.P. Pudasaini [ Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn, Germany ]
- S. A. Miller [ Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn, Germany ]
Date: 2009
Abstract: The powerful avalanche simulation toolbox RAMMS (Rapid Mass Movements) is based on a depth-averaged hydrodynamic system of equations with a Voellmy-Salm friction relation. The two empirical friction parameters μ and correspond to a dry Coulomb friction and a viscous resistance, respectively. Although μ and lack a proper physical explanation, 60 years of acquired avalanche data in the Swiss Alps made a systematic calibration possible. RAMMS can therefore successfully model avalanche flow depth, velocities, impact pressure and run out distances. Pudasaini and Hutter (2003) have proposed extended, rigorously derived model equations that account for local curvature and twist. A coordinate transformation into a reference system, applied to the actual mountain topography of the natural avalanche path, is performed. The local curvature and the twist of the avalanche path induce an additional term in the overburden pressure. This leads to a modification of the Coulomb friction, the free-surface pressure gradient, the pressure induced by the channel, and the gravity components along and normal to the curved and twisted reference surface. This eventually guides the flow dynamics and deposits of avalanches. In the present study, we investigate the influence of curvature on avalanche flow in real mountain terrain. Simulations of real avalanche paths are performed and compared for the different models approaches. An algorithm to calculate curvature in real terrain is introduced in RAMMS. This leads to a curvature dependent friction relation in an extended version of the Voellmy-Salm model equations. Our analysis provides yet another step in interpreting the physical meaning and significance of the friction parameters used in the RAMMS computational environment.
Language of Article: English
Presenters: Unknown
Keywords: snow, avalanche, dynamics, modeling, natural terrain, curvature
Page Number(s): 448-453
Subjects: dynamic avalanche modeling natural terrain curvature
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Digital Abstract Not Available
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