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| Titel |
Empirical atmospheric thresholds for debris flows and flash floods in the southern French Alps |
| VerfasserIn |
T. Turkington, J. Ettema, C. J. van Westen, K. Breinl |
| 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 ; 14, no. 6 ; Nr. 14, no. 6 (2014-06-18), S.1517-1530 |
| Datensatznummer |
250118500
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| Publikation (Nr.) |
 copernicus.org/nhess-14-1517-2014.pdf |
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| Zusammenfassung |
Debris flows and flash floods are often preceded by intense, convective
rainfall. The establishment of reliable rainfall thresholds is an important
component for quantitative hazard and risk assessment, and for the
development of an early warning system. Traditional empirical thresholds
based on peak intensity, duration and antecedent rainfall can be difficult to
verify due to the localized character of the rainfall and the absence of
weather radar or sufficiently dense rain gauge networks in mountainous
regions. However, convective rainfall can be strongly linked to regional
atmospheric patterns and profiles. There is potential to employ this in
empirical threshold analysis.
This work develops a methodology to determine robust thresholds for flash
floods and debris flows utilizing regional atmospheric conditions derived
from ECMWF ERA-Interim reanalysis data, comparing the results with rain-gauge-derived thresholds. The method includes selecting the appropriate atmospheric
indicators, categorizing the potential thresholds, determining and testing
the thresholds. The method is tested in the Ubaye Valley in the southern
French Alps (548 km2), which is known to have localized convection
triggered debris flows and flash floods. This paper shows that instability of
the atmosphere and specific humidity at 700 hPa are the most important
atmospheric indicators for debris flows and flash floods in the study area.
Furthermore, this paper demonstrates that atmospheric reanalysis data are an
important asset, and could replace rainfall measurements in empirical
exceedance thresholds for debris flows and flash floods. |
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