Regional growth curves and extreme precipitation events estimation in the steppe area of northwestern Algeria

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Abdelkader Boucefiane
Mohamed Meddi

Abstract

A regional statistical analysis has been established for an improved estimate of extreme frequency precipitation in the steppe area of northwestern Algeria. This analysis made it possible to determine three homogeneous regions by using methods based on statistical procedures, such as the analysis of the ascendant hierarchical classification and the L-moments method. The regions thus defined accurately reflect the climatological differences and specific characters influencing precipitation patterns in the study area. The generalized extreme value (GEV) distribution has been identified as the most appropriate distribution for modeling annual maximum daily rainfall quantiles according to the L-moments ratio plot and fit-quality tests. Rainfall indices combined with the regional growth curves can evaluate in a reasonable way the maximum rainfall quantiles at the stations by using the mean maximum precipitations of the observation series. The regional approach has considerably reduced the differences caused by the disparity of the values taken by the shape parameter of the GEV distribution as a function of the observation sites, and the estimation of high quantiles becomes more spatially consistent in a region. Different forms of growth curves are characteristic for the three regions. The error reflected by the bias and root mean square error (RMSE) are below 16 and 25%, respectively, for a 100-year return period. The study provides an assessment of the maximum daily rainfalls that can be useful in the study of floods and the design of hydrotechnical works.

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Author Biographies

Abdelkader Boucefiane, Djilali Bounaama University of Khemis Miliana, Route Theniet El Had 44225 Khemis Miliana, Ain Defla, Algéria a.boucefiane @univ-dbkm.dz LGEE – Higher National School of Hydraulic, BP 31, 09000 Blida, Algeria Fax: 213-25-39-94-46 Boucefiane_Abdelkader @yahoo.fr

Abdelkader Boucefiane is a Dr in hydrology, hydrogeology and water quality and Teacher researcher at Earth sciences Departement at the Djillali Bounaama University of Khemis Miliana, UDBKM, Algeria. He has participated at several research projects in the LGEE Laboratory in the Higher National School of Hydraulics, Blida, Algeria, in hydrology and water sciences.

 

Mohamed Meddi, LGEE – Higher National School of Hydraulic, Blida, Algeria BP 31, 09000 Blida, Algeria Fax: 213-25-39-94-46 mmeddi@yahoo.fr

Mohamed Meddi is a Professor, Researcher, the Director of Research at the
LGEE Laboratory in the Higher National School of Hydraulics, Blida, Algeria,
and a study leader in several research teams. He has published a wide variety of
scientific works, reports and conference papers in hydrology and water
sciences.

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