http://www.cnr.it/ontology/cnr/individuo/prodotto/ID312499
Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence (Abstract/Poster in atti di convegno)
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- Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence (Abstract/Poster in atti di convegno) (literal)
- Anno
- 2014-01-01T00:00:00+01:00 (literal)
- Alternative label
Efthymios I. Nikolopoulos, Marco Borga, Stefano Crema , Lorenzo Marchi, Francesco Marra, and Fausto Guzzetti (2014)
Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence
in EGU General Assembly 2014, Vienna (Austria), 27 April - 2 May 2014
(literal)
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- Efthymios I. Nikolopoulos, Marco Borga, Stefano Crema , Lorenzo Marchi, Francesco Marra, and Fausto Guzzetti (literal)
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- Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro, PD, Italy; Consiglio
Nazionale delle Ricerche, IRPI, Padova, Italy; Department of Geography, Hebrew University of Jerusalem, Israel;
Consiglio Nazionale delle Ricerche, IRPI, Perugia, Italy (literal)
- Titolo
- Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence (literal)
- Abstract
- Estimation of rainfall intensity-duration thresholds, used for the identification of debris flows/landslides triggering
rainfall events, has been traditionally based on raingauge observations. The main drawback of using information
from gauges is that rainfall estimates are available only over gauge locations, which are usually located far away
from the debris flow/landslide initiation areas. Thus, successful implementation of gauge-based rainfall thresholds
involves the intrinsic assumption that rainfall over gauge and actual initiation point is highly correlated. However,
in complex terrain where this natural hazard takes place, spatial variability of rainfall can be very high even at very
small scales due to orographic enhancement of precipitation and the development of highly localized convective
systems.
This work is focused on the assessment of the impact of rainfall estimation uncertainty on identification and
use of rainfall thresholds for debris flow occurrence. The Upper Adige river basin, northern Italy, is the area of
study. A detailed database of more than 400 identified debris flows during period 2000-2010 and a raingauge
network of 95 stations, is used for this work. The methodology examines the intensity-duration thresholds derived
from a set of raingauge locations that is assumed to be collocated with debris flow/landslide points (DFR) and
an equivalent set of raingauges assumed to have the role of closest available measurement (MR). Comparison
between the rainfall thresholds derived from DFR and MR, revealed that uncertainty in rainfall estimation has
a major impact on estimated intensity-duration thresholds. Specifically, results showed that thresholds estimated
from MR observations are consistently underestimated. Evaluation of the estimated thresholds for warning
procedures showed that while detection is high, the main issue is the high false alarm ratio, which limits the overall
accuracy of the procedure. Overall performance on debris flow prediction was shown to be good for low rainfall
thresholds and poor for high rainfall thresholds examined. These findings have consequences in the operational
use of the thresholds and provide evidence of the regional dependence of uncertainty in estimation of ID thresholds. (literal)
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