Topographic curvature effects in applied avalanche modeling

Fischer, Jan-Thomas; Kowalski, Julia; Pudasaini, Shiva P.

doi:10.1016/j.coldregions.2012.01.005

Cited by 106 publications

(105 citation statements)

References 42 publications

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“…We use the simplest version based on Voellmy's rheology, neglecting entrainment (Christen et al, 2010) and do not use the recently introduced features of extending Voellmy's rheology by cohesion and taking into account the effect of surface curvature on the frictional force considered by Fischer et al (2012). However, all these extensions can in principle be adjusted to our formulation based on the shallow water equations in Cartesian coordinates.…”

Section: Validationmentioning

confidence: 99%

“…Here and in the following, the curvature of the smooth transition zone is defined in such a way that an avalanche entering from the upper ramp with the terminal velocity according to Eq. (28) is exposed to an centrifugal acceleration of about 1 m s −2 (which is neglected in both RAMMS and our approach but considered in detail by Fischer et al, 2012).…”

Section: The Effect Of Profile Curvaturementioning

confidence: 99%

“…The software RAMMS (Christen et al, 2010) implements the simplest version of such a local coordinate system by neglecting the surface curvature. Potential limitations arising from this approximation were discussed by Fischer et al (2012), presenting an extension taking the surface curvature into account for the price of more complicated differential equations. A general formulation for arbitrary coordinate systems was provided by Bouchut and Westdickenberg (2004).…”

Section: Introductionmentioning

confidence: 99%

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Modelling rapid mass movements using the shallow water equations in Cartesian coordinates

Hergarten

Robl

2015

Nat. Hazards Earth Syst. Sci.

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Abstract. We propose a new method to model rapid mass movements on complex topography using the shallow water equations in Cartesian coordinates. These equations are the widely used standard approximation for the flow of water in rivers and shallow lakes, but the main prerequisite for their application -an almost horizontal fluid table -is in general not satisfied for avalanches and debris flows in steep terrain. Therefore, we have developed appropriate correction terms for large topographic gradients. In this study we present the mathematical formulation of these correction terms and their implementation in the open-source flow solver GERRIS. This novel approach is evaluated by simulating avalanches on synthetic and finally natural topographies and the widely used Voellmy flow resistance law. Testing the results against analytical solutions and the proprietary avalanche model RAMMS, we found a very good agreement. As the GERRIS flow solver is freely available and open source, it can be easily extended by additional fluid models or source areas, making this model suitable for simulating several types of rapid mass movements. It therefore provides a valuable tool for assisting regional-scale natural hazard studies.

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Section: Validationmentioning

confidence: 99%

Section: The Effect Of Profile Curvaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modelling rapid mass movements using the shallow water equations in Cartesian coordinates

Hergarten

Robl

2015

Nat. Hazards Earth Syst. Sci.

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“…(16) on forest damage by dry flowing avalanche cores, we implemented a new module in the avalanche simulation program RAMMS (Christen et al, 2010b). We accounted for the turbulent movement of particles, curvature effects, snow temperature and cohesion (Buser and Bartelt, 2009;Fischer et al, 2012;Vera et al, 2015;Bartelt et al, 2014Bartelt et al, , 2015. Avalanche flow regime depends on snow temperature and moisture content .…”

Section: Forest Destruction Modelingmentioning

confidence: 99%

Forest damage and snow avalanche flow regime

Feistl

Bebi²,

Christen³

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Snow avalanches break, uproot and overturn trees causing damage to forests. The extent of forest damage provides useful information on avalanche frequency and intensity. However, impact forces depend on avalanche flow regime. In this paper, we define avalanche loading cases representing four different avalanche flow regimes: powder, intermittent, dry and wet. Using a numerical model that simulates both powder and wet snow avalanches, we study documented events with forest damage. First we show that in the powder regime, although the applied impact pressures can be small, large bending moments in the tree stem can be produced due to the torque action of the blast. The impact area of the blast extends over the entire tree crown. We find that, powder clouds with velocities over 20 m s −1 can break tree stems. Second we demonstrate that intermittent granular loadings are equivalent to low-density uniform dry snow loadings under the assumption of homogeneous particle distributions. The intermittent regime seldom controls tree breakage. Third we calculate quasi-static pressures of wet snow avalanches and show that they can be much higher than pressures calculated using dynamic pressure formulas. Wet snow pressure depends both on avalanche volume and terrain features upstream of the tree.

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“…The total acceleration in the slope perpendicular direction is denoted g ; it is composed of the slope perpendicular component of gravity g z , dispersive accelerationẇ Φ and centripetal accelerations f z , (Fischer et al, 2012). The total normal force at the base of the avalanche is given by N ,…”

mentioning

confidence: 99%

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

Valero¹,

Wever²,

Christen³

et al. 2017

Preprint

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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.

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Topographic curvature effects in applied avalanche modeling

Cited by 106 publications

References 42 publications

Modelling rapid mass movements using the shallow water equations in Cartesian coordinates

Modelling rapid mass movements using the shallow water equations in Cartesian coordinates

Forest damage and snow avalanche flow regime

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

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