CARACTERISATION DE LA PLUVIOMETRIE DU BASSIN VERSANT DE L'OUEME AU BENIN : ETABLISSEMENT DES COURBES INTENSITE-DUREE-FREQUENCE DES PRECIPITATIONS

The present work has for objective the survey of the features of the rainfall observed on the Oueme's basin and the establishment of the Intensity-Duration-Frequency curves (IDF) of the precipitations very used in the conception of the hydraulic works and Civil Engineering. The extreme annual daily rainfalls of 37 rainfall stations of Benin installed on the Oueme's basin have been analyzed on the period 1971- 2010. Then, they have been adjusted to an extreme value law selected among the laws of Jenkinson and Gumbel according to the Kolmogorov-Smirnov test. These tests permitted to regionalize the laws of adjustment in distinct two zones of application: the law of Jenkinson appears more adequate to the zone South while the law of Gumbel suits the North zone of Benin better; what makes notice the non consistency of the exclusive use of the law of Gumbel at the time of the studies of conception of hydraulic works on the whole territory. The evaluation of the quantiles relative of daily rain to the period's back 2, 5, 10, 20, 50 and 100 years revealed that the maximal heights of water of rare frequency are observed at the Cotonou-Airport station on the Coastline and the maximal heights of water weakest in Ina's region to the North of Benin. The determination of the influence zones, climatic exponents of every station and the quantiles of maxim daily rains permitted to define the heights of rain of short lengths to act as basis to the establishment of the curves local IDF by means of the models of Montana, Talbot and Keifer -Chu. In conclusion; the model of Talbot, having a stronger physical and probabilistic basis than the classic Montana formula used for the modeling of the IDF curves, is more adequate.

basin, rain, intensity, duration, frequency, curves