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| Titel |
Hydrometeorological threshold conditions for debris flow initiation in Norway |
| VerfasserIn |
N. K. Meyer, A. V. Dyrrdal, R. Frauenfelder, B. Etzelmüller, F. Nadim |
| 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. 10 ; Nr. 12, no. 10 (2012-10-11), S.3059-3073 |
| Datensatznummer |
250011143
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| Publikation (Nr.) |
 copernicus.org/nhess-12-3059-2012.pdf |
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| Zusammenfassung |
| Debris flows, triggered by extreme precipitation events and rapid snow melt,
cause considerable damage to the Norwegian infrastructure every year. To
define intensity-duration (ID) thresholds for debris flow initiation
critical water supply conditions arising from intensive rainfall or snow
melt were assessed on the basis of daily hydro-meteorological information
for 502 documented debris flow events. Two threshold types were computed:
one based on absolute ID relationships and one using ID relationships
normalized by the local precipitation day normal (PDN). For each threshold
type, minimum, medium and maximum threshold values were defined by fitting
power law curves along the 10th, 50th and 90th percentiles of
the data population. Depending on the duration of the event, the absolute
threshold intensities needed for debris flow initiation vary between 15 and
107 mm day−1. Since the PDN changes locally, the normalized thresholds show
spatial variations. Depending on location, duration and threshold level, the
normalized threshold intensities vary between 6 and 250 mm day−1. The
thresholds obtained were used for a frequency analysis of over-threshold
events giving an estimation of the exceedance probability and thus potential
for debris flow events in different parts of Norway. The absolute thresholds
are most often exceeded along the west coast, while the normalized
thresholds are most frequently exceeded on the west-facing slopes of the
Norwegian mountain ranges. The minimum thresholds derived in this study are
in the range of other thresholds obtained for regions with a climate
comparable to Norway. Statistics reveal that the normalized threshold is
more reliable than the absolute threshold as the former shows no spatial
clustering of debris flows related to water supply events captured by the
threshold. |
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