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| Titel |
A peaks-over-threshold model for floods with zero-inflated Poisson arrivals |
| VerfasserIn |
Artur Tiago Silva, Maria Manuela Portela, Mauro Naghettini |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072065
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| Zusammenfassung |
| The peaks-over-threshold (POT) model for hydrological extremes with Poisson arrivals and
Generalized Pareto (GP) distributed exceedances remains a popular and useful tool for
modelling hydrologic extremes. The use of the Poisson-GP model for flood frequency
analysis requires the validation of the Poisson hypothesis: that the distribution of the annual
number of flood events may be described by a Poisson distribution. Such hypothesis is not
always valid in practical applications.
The present study concerns the use of an alternative distribution for modelling the annual
number of floods - the Zero-Inflated Poisson (ZIP) distribution with two parameters. A
ZIP-GP model for flood frequency analysis is proposed. This model is less restrictive than the
Poisson-GP model since it allows for a more accurate description of the occurrence process in
a POT framework if the fraction of years with no exceedances is significantly higher than the
theoretical density at zero of the Poisson distribution. Applications of the ZIP-GP model to
flood data from Northern Portugal and the evaluation of its performance relative to the
Poisson-GP model, including assessments of quantile uncertainty, are presented. The
results show that, overall, the ZIP-GP model outperforms the Poisson-GP model,
especially for lower quantiles, hence the ZIP distribution is a valid alternative to the
Poisson distribution for modelling the annual occurrence counts of peaks in a POT
approach for flood frequency analysis. Moreover, despite the ZIP having one more
parameter, there is no increment in uncertainty for higher quantiles of the ZIP-GP model. |
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