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| Titel |
An elusive search for regional flood frequency estimates in the River Nile basin |
| VerfasserIn |
P. Nyeko-Ogiramoi, P. Willems, F. M. Mutua, S. A. Moges |
| 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 ; 16, no. 9 ; Nr. 16, no. 9 (2012-09-06), S.3149-3163 |
| Datensatznummer |
250013460
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| Publikation (Nr.) |
 copernicus.org/hess-16-3149-2012.pdf |
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| Zusammenfassung |
| Estimation of peak flow quantiles in ungauged catchments is a challenge
often faced by water professionals in many parts of the world. Approaches to
address such problem exist, but widely used techniques such as flood frequency
regionalisation is often not subjected to performance evaluation. In this
study, the jack-knifing principle is used to assess the performance of the
flood frequency regionalisation in the complex and data-scarce River Nile
basin by examining the error (regionalisation error) between locally and
regionally estimated peak flow quantiles for different return periods
(QT). Agglomerative hierarchical clustering based algorithms were used
to search for regions with similar hydrological characteristics.
Hydrological data employed were from 180 gauged catchments and several
physical characteristics in order to regionalise 365 identified catchments.
The Generalised Extreme Value (GEV) distribution, selected using L-moment based approach, was used to
construct regional growth curves from which peak flow growth factors could
be derived and mapped through interpolation. Inside each region, variations
in at-site flood frequency distribution were modelled by regression of the
mean annual maximum peak flow (MAF) versus catchment area. The results
showed that the performance of the regionalisation is heavily dependent on
the historical flow record length and the similarity of the hydrological
characteristics inside the regions. The flood frequency regionalisation of
the River Nile basin can be improved if sufficient flow data of longer
record length of at least 40 yr become available. |
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