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| Titel |
Forest damage and snow avalanche flow regime |
| VerfasserIn |
T. Feistl, P. Bebi, M. Christen, S. Margreth, L. Diefenbach, P. Bartelt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 15, no. 6 ; Nr. 15, no. 6 (2015-06-18), S.1275-1288 |
| Datensatznummer |
250119536
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| Publikation (Nr.) |
 copernicus.org/nhess-15-1275-2015.pdf |
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| Zusammenfassung |
| 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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