Scientific newssheets
Africa’s monsoon challenge
September 2009
The monsoon sets the pattern of life of 300 million West Africans. The intensity and duration of the rains it brings govern all crop cultivation and water resources – and hence food security. In a period of less than four months, from June to September, it brings the greater part of the rainfall for the whole year. However, it has lost its intensity over the past decades, plunging the Sahel into a succession of famines.
As part of the international programme AMMA1, IRD research scientists and their partners have been making long-term observations on this erratic monsoon system in order to predict the consequences. The observation system AMMA-CATCH (Couplage de l’Atmosphère Tropicale et du Cycle Hydrologique
), launched in 2002 to study the coupling between the tropical atmosphere and the hydrological cycle, has brought to the fore certain characteristics and paradoxes of the water cycle associated with the African monsoon: a significant change in the season cycle and a decrease in the number of substantial rainfall events, but an increase in surface runoff and flooding in a greener Sahel.
