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| Titel |
Derivation of critical rainfall thresholds for shallow landslides as a tool for debris flow early warning systems |
| VerfasserIn |
M. N. Papa, V. Medina, F. Ciervo, A. Bateman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 10 ; Nr. 17, no. 10 (2013-10-23), S.4095-4107 |
| Datensatznummer |
250085966
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| Publikation (Nr.) |
 copernicus.org/hess-17-4095-2013.pdf |
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| Zusammenfassung |
| Real-time assessment of debris-flow hazard is fundamental for developing
warning systems that can mitigate risk. A convenient method to assess the
possible occurrence of a debris flow is to compare measured and forecasted
rainfalls to critical rainfall threshold (CRT) curves. Empirical derivation
of the CRT from the analysis of past events' rainfall characteristics is not
possible when the database of observed debris flows is poor or when the
environment changes with time. For debris flows and mud flows triggered by
shallow landslides or debris avalanches, the above limitations may be
overcome through the methodology presented. In this work the CRT curves are
derived from mathematical and numerical simulations, based on the
infinite-slope stability model in which slope instability is governed by the
increase in groundwater pressure due to rainfall. The effect of rainfall
infiltration on landside occurrence is modelled through a reduced form of the
Richards equation. The range of rainfall durations for which the method can
be correctly employed is investigated and an equation is derived for the
lower limit of the range. A large number of calculations are performed
combining different values of rainfall characteristics (intensity and
duration of event rainfall and intensity of antecedent rainfall). For each
combination of rainfall characteristics, the percentage of the basin that is
unstable is computed. The obtained database is opportunely elaborated to
derive CRT curves. The methodology is implemented and tested in a small basin
of the Amalfi Coast (South Italy). The comparison among the obtained CRT
curves and the observed rainfall amounts, in a playback period, gives a good
agreement. Simulations are performed with different degree of detail in the
soil parameters characterization. The comparison shows that the lack of
knowledge about the spatial variability of the parameters may greatly affect
the results. This problem is partially mitigated by the use of a Monte Carlo
approach. |
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