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| Titel |
Rainfall intensity–duration thresholds for bedload transport initiation in small Alpine watersheds |
| VerfasserIn |
A. Badoux, J. M. Turowski, L. Mao, N. Mathys, D. Rickenmann |
| 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 (2012-10-18), S.3091-3108 |
| Datensatznummer |
250011145
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| Publikation (Nr.) |
 copernicus.org/nhess-12-3091-2012.pdf |
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| Zusammenfassung |
Although channel discharge represents one of the primary controls of bedload
transport rates in mountain streams, it is rarely measured in small, steep
catchments. Thus, it is often impossible to use it as a predictor of
hazardous bedload events. In this study, the characteristics of rainfall
events leading to bedload transport were investigated in five small Alpine
catchments located in different geographical and morphological regions of
Switzerland, Italy and France. Using rainfall data at high temporal
resolution, a total of 370 rainfall events were identified that led to
abundant sediment transport in the different catchments, and corresponding
threshold lines were defined using a power law in intensity–duration space.
Even though considerable differences in the distribution of the rainfall
data were identified between catchments located in various regions, the
determined threshold lines show rather similar characteristics.
Such threshold lines indicate critical conditions for bedload transport
initiation, but rainfall events that do not cause transport activity (so
called no-bedload events) can still plot above them. With 0.67 overall in
the Erlenbach (Swiss Prealps) and 0.90 for long-duration, low-intensity
rainfall, the false alarm rate is considerable. However, for short-duration,
high-intensity events, it is substantially smaller (0.33) and comparable to
values determined in previous studies on the triggering of Alpine debris
flows. Our results support the applicability of a traditional, generalized
threshold for prediction or warning purposes during high-intensity rainfall.
Such (often convective) rainfall events are unfortunately (i) difficult to
measure, even by dense rain gauge networks, and (ii) difficult to accurately
predict, both due to their small spatial and temporal scales. Still, for the
protection of human life (e.g. along transportation infrastructure such as
roads and railway) automated alerts based on power law threshold lines may
be useful. |
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