Évolution des Descripteurs Intrasaisonniers des Saisons Pluvieuses Au sud-Bénin Entre 1951 et 2010

Abstract

This study analyzed the evolution of intraseasonal characteristics of rainy seasons in the south of Benin from 1951 to 2010. For this purpose, daily rainfall records (1951-2010) from 14 stations were used. This period was divided into three sub-periods of 20 years: 1951-1970, 1971-1990 and 1991-2010. Trends between the sub-periods show that the intermediate sub-period (1971-1990) is the driest. After 1990, we note an increase in rainfall, but this last sub-period (1991-2010) remains drier than the wettest sub-period (1951-1970). This study showed that the first and the second rainy season are not affected in the same way by the atmospheric forcing. After 1990, while the quality of the second rainy season again became comparable to that of 1951-1970, the first rainy season remained precarious, comparable to that of 1971-1990. In addition, after 1970, the first rainy season shortened mainly because of its delay, while the second rainy season has lengthened due to its early onset. These changes of season’s length and quality open the importants questions of the adaptation of agricultural strategies.