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| Titel |
Wet-snow avalanche interaction with a deflecting dam: field observations and numerical simulations in a case study |
| VerfasserIn |
B. Sovilla, I. Sonatore, Y. Bühler, S. Margreth |
| 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 Science ; 12, no. 5 ; Nr. 12, no. 5 (2012-05-11), S.1407-1423 |
| Datensatznummer |
250010808
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| Publikation (Nr.) |
 copernicus.org/nhess-12-1407-2012.pdf |
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| Zusammenfassung |
In avalanche-prone areas, deflecting dams are widely used to
divert avalanches away from endangered objects. In recent years,
their effectiveness has been questioned when several large and
multiple avalanches have overrun such dams.
In 2008, we were able to observe a large wet-snow avalanche,
characterized by an high water content, that interacted with a
deflecting dam and overflowed it at its lower end. To evaluate the
dam's performance, we carried out an airborne laser scanning
campaign immediately after the avalanche. This data, together with
a video sequence made during the avalanche descent, provided a
unique data set to study the dynamics of a wet dense snow
avalanche and its flow behavior along a deflecting dam.
To evaluate the effect of the complex flow field of the avalanche
along the dam and to provide a basis for discussion of the
residual risk, we performed numerical simulations using a
two-dimensional dense snow avalanche dynamics model with
entrainment.
In comparison to dry dense snow avalanches, we found that wet-snow
avalanches, with high water content, seem to be differently
influenced by the local small-scale topography roughness. Rough
terrain close to the dam deflected the flow to produce abrupt
impacts with the dam. At the impact sites, instability waves were
generated and increased the already large flow depths. The complex
flow dynamics around the dam may produce large, local snow
deposits. Furthermore, the high water content in the snow may
decrease the avalanche internal friction angle, inducing wet-snow
avalanches to spread further laterally than dry-snow avalanches.
Based on our analysis, we made recommendations for designing
deflecting dams and for residual risk analysis to take into
account the effects of wet-snow avalanche flow. |
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