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| Titel |
Regional evaluation of three day snow depth for avalanche hazard mapping in Switzerland |
| VerfasserIn |
D. Bocchiola, E. Bianchi Janetti, E. Gorni, C. Marty, B. Sovilla |
| 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 ; 8, no. 4 ; Nr. 8, no. 4 (2008-07-16), S.685-705 |
| Datensatznummer |
250005642
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| Publikation (Nr.) |
 copernicus.org/nhess-8-685-2008.pdf |
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| Zusammenfassung |
| The distribution of the maximum annual three day snow fall depth H72,
used for avalanche hazard mapping according to the Swiss procedure (Sp), is
investigated for a network of 124 stations in the Alpine part of
Switzerland, using a data set dating back to 1931. Stationarity in time is
investigated, showing in practice no significant trend for the considered
period. Building on previous studies about climatology of Switzerland and
using an iterative approach based on statistical tests for regional
homogeneity and scaling of H72 with altitude, seven homogenous
regions are identified. A regional approach based on the index value is then
developed to estimate the T-years return period quantiles of H72 at each
single site i, H72i(T). The index value is the single site sample average
μH72i. The dimensionless values of H*72i=H72i / μH72i are
grouped in one sample for each region and their frequency of occurrence is
accommodated by a General Extreme Value, GEV, probability distribution,
including Gumbel. The proposed distributions, valid in each site of the
homogeneous regions, can be used to assess the T-years return period
quantiles of H*72i. It is shown that the value of
H72i(T) estimated with the regional approach is more accurate than that
calculated by single site distribution fitting, particularly for high return
periods. A sampling strategy based on accuracy is also suggested to estimate
the single site index value, i.e. the sample average μH72i, critical for the
evaluation of the distribution of H72i. The proposed regional approach
is valuable because it gives more accurate snow depth input to dynamics
models than the present procedure based on single site analysis, so
decreasing uncertainty in hazard mapping procedure. |
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