Caractérisation spatio-temporelle du régime pluviométrique du haut bassin du fleuve Sénégal dans un contexte de variabilité climatique
Runoff and consequently water resources constitute the response of watersheds to pluviometric impulses. In Central and West Africa, one attends since the 1970s with a without precedent dryness just as a great space and temporal variability of the rainfall, characteristic of the tropical field. The o...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Physio-Géo
2011-07-01
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| Series: | Physio-Géo |
| Subjects: | |
| Online Access: | https://journals.openedition.org/physio-geo/1958 |
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| Summary: | Runoff and consequently water resources constitute the response of watersheds to pluviometric impulses. In Central and West Africa, one attends since the 1970s with a without precedent dryness just as a great space and temporal variability of the rainfall, characteristic of the tropical field. The objective of this work is to define this space-time variability of precipitations on the scale of the upper basin of the Senegal River starting from the data of ten reference stations. The choice of the stations follows criteria of data quality (weak gaps) and proximity to the catchment area. Initially, the statistical tests of homogeneity were applied to the series of annual rainfalls from the origin of the stations until 2005. The analyzed series all present ruptures. Eight of the ten studied stations present a rupture ranging between 1960 and 1970 and the subsequent deficits vary from 12 % to 24 %. At a monthly time step, after reconstitution of the missing data, it appears that rainfall decreases significantly for almost all months between the two periods. At a daily time step, the analysis of the daily pluviometric fractions highlights a tendency to the reduction of the mean annual amount of the rains higher than 40 mm (which are regarded as the heavy rains) as from the years of ruptures. We also characterized the space variability of the mean annual rainfall for periods of 30 or 10 years and then the variations are compared to the period of reference 1961-1970. This shows that the south of the basin presents the most significant surpluses during the surplus periods, but also the most significant deficits in overdrawn periods. |
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| ISSN: | 1958-573X |