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| Titel |
The effect of scale in daily precipitation hazard assessment |
| VerfasserIn |
J. J. Egozcue, V. Pawlowsky-Glahn, M. I. Ortego, R. Tolosana-Delgado |
| 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 ; 6, no. 3 ; Nr. 6, no. 3 (2006-06-06), S.459-470 |
| Datensatznummer |
250003509
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| Publikation (Nr.) |
 copernicus.org/nhess-6-459-2006.pdf |
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| Zusammenfassung |
| Daily precipitation is recorded as the total amount of water
collected by a rain-gauge in 24 h. Events are modelled as a
Poisson process and the 24 h precipitation by a Generalised
Pareto Distribution (GPD) of excesses. Hazard assessment is
complete when estimates of the Poisson rate and the distribution
parameters, together with a measure of their uncertainty, are
obtained.
The shape parameter of the GPD determines the support of
the variable: Weibull domain of attraction (DA) corresponds to
finite support variables as should be for natural phenomena.
However, Fréchet DA has been reported for daily precipitation,
which implies an infinite support and a heavy-tailed distribution.
Bayesian techniques are used to estimate the parameters.
The approach is illustrated with precipitation data from
the Eastern coast of the Iberian Peninsula affected by severe
convective precipitation. The estimated GPD is mainly in the
Fréchet DA, something incompatible with the common sense
assumption of that precipitation is a bounded phenomenon.
The bounded character of precipitation is then taken as a priori
hypothesis. Consistency of this hypothesis with the data is
checked in two cases: using the raw-data (in mm) and using log-transformed
data. As expected, a Bayesian model checking clearly rejects
the model in the raw-data case. However, log-transformed data
seem to be consistent with the model. This fact may be due to
the adequacy of the log-scale to represent positive measurements
for which differences are better relative than absolute. |
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