Publications des scientifiques de l'IRD

Frappart F., Hiernaux P., Guichard F., Mougin Eric, Kergoat L., Arjounin Marc, Lavenu François, Koite M., Paturel Jean-Emmanuel, Lebel Thierry. (2009). Rainfall regime across the Sahel band in the Gourma region, Mali. Journal of Hydrology, 375 (1-2), p. 128-142. ISSN 0022-1694.

Titre du document
Rainfall regime across the Sahel band in the Gourma region, Mali
Année de publication
2009
Type de document
Article référencé dans le Web of Science WOS:000270472000011
Auteurs
Frappart F., Hiernaux P., Guichard F., Mougin Eric, Kergoat L., Arjounin Marc, Lavenu François, Koite M., Paturel Jean-Emmanuel, Lebel Thierry
Source
Journal of Hydrology, 2009, 375 (1-2), p. 128-142 ISSN 0022-1694
The Sahel is characterized by low and highly variable rainfall, which strongly affects the hydrology and the climate of the region and creates severe constraints for agriculture and water management. This study provides the first characterization of the rainfall regime for the Gourma region located in Mali, Century Sahel (14.5-17.5 degrees N and 2-1 degrees S). The rainfall regime is described using two datasets: the daily long term raingauge records covering the period 1950-2007, and the high frequency raingauge records collected under the African Monsoon Multidisciplinary Analysis (AMMA) project between 2005 and 2008. The first rainfall dataset was used to analyse the interannual variability and the spatial distribution of the precipitation. The second dataset is used to analyse the diurnal cycle of precipitation and the nature of the rainfall. This study is complementary to previous analyses conducted in Sahelian areas located further south, where the influence of the continental Sahara heat low is expected to be less pronounced in summer. Rainfall regimes in the Gourma region present a succession of wet (1950-1969) and dry decades (1970-2007). The decrease of summer cumulative rainfall is explained by a reduction in the number of the rainy days in southern Gourma, and a decrease in both the number of rainy days and the daily rainfall in northern and central Gourma. This meridional difference may be related to the relative distances of the zones from the intertropical discontinuity, which is closer to the northern stations. The length of the rainy season has varied since the 1950s with two episodes of shorter rainy seasons: during the drought of the 1980s and also since 2000. However, this second episode is characterized by an increase in the daily rainfall, which suggests an intensification of rainfall events in the more recent years. High-frequency data reveal that a large fraction of the rainfall is produced by intense rain events mostly occurring in late evenings and early mornings during the core of the rainy season (July-September). Conversely, rainfall amounts are less around noon, and this mid-day damping is more pronounced in northern Gourma. All these characteristics have strong implications for agriculture and water resources management.
Plan de classement
Hydrologie [062]
Localisation
Fonds IRD [F B010048239]
Identifiant IRD
fdi:010048239
Contact