AMMA-CATCH is a National Observation Service (SNO) that aims to document the long-term climatic, hydrological and ecological evolution in West Africa. It is based on three densely instrumented sites, some of which have been operating since the mid-1980s on the Sahelian part of the observatory. The surface area of these three sites is between 10,000 and 25,000 km²; they are staggered in latitude so as to sample the eco-climatic gradients characteristic of the region.
Simultaneous monitoring of these three sites of the vegetation cover, its phenology and the different terms of the water balance (rain, infiltration, aquifer recharge, surface runoff) makes it possible to better understand the interactions between the water cycle and the dynamics of the water. vegetation and climate variability at intra-seasonal to multi-year scales in this region highly vulnerable to the impacts of climate change.