AMMA-CATCH observatory

AMMA-CATCH observatory

Scientific context

West Africa is a region in a rapid transition in terms of climat, demography and land use. In this context, the AMMA-CATCH long-term observary has been developed to monitor the impacts of global change on the Critical Zone of West Africa and to better understand is current and future dynamics. The observatory relies on sites about 10 000 km² each. These sites are staggered in latitude in order to sample the ecoclimatic gradient, characteristic of this region. From north to south we find: the Gourma site (Mali) in a semi-arid climate (rainfall ~ 300 mm/year), the Niamey square degree site (Niger) in a Sahelian climate (rainfall ~ 600 mm/year) and the Upper Ouémé site (Benin) in a Sudanian climate (rainfall ~ 1200 mm/year). A fourth site was installed in Senegal in 2013, sahelian, and allows to sample the East-West longitudinal gradient.

Summary

Starting year: 1990 (Niger), 1996 (Benin), 2005 (Mali), 2013 (Senegal)

Localisations: Mali, Benin, Senegal and Niger

Key words: monsoon, Sahelian and Sudanian climate, nested sites, hydrology, evapotranspiration, water resources

Database: http://bd.amma-catch.org/

Web site:  www.amma-catch.org

PIs: Sylvie Galle,
Manuela Grippa,
Christophe Peugeot,
contact@amma-catch.org

Le site de Hombori pendant la saison des pluies (Mali)
Hombori site during the wet season (Mali) © Eric Mougin

Scientific questions

What is the impact of climat changes and land use on water and vegetation cycles in West-Africa? The long-term observations of the AMMA-CATCH observatory aim to:

  • Understand the main processes that govern water and vegetation cycles;
  • Provide a regional vision of the evolution of the environmental systems;
  • Improve the modeling of continental surfaces in West;
  • Provide tools to decision makers and public actors for decision support.

Sites and measured variables

The observation strategy is based on a nesting of scales. The observation of hydrologic processes is reinforced on “supersites” (~ 100 km²) and the monitoring of vegetation dynamic and associated water flux is done on “local intensive sites” (~ 1 ha²) which represent the main vegetation cover of the site considered.

AMMA-CATCH sites are instrumented to provide homogenous data (same instruments, same protocols for data processing) on the same variables: Les sites AMMA-CATCH sont équipés pour fournir des données homogènes (mêmes instruments, mêmes protocoles pour le traitement des données) sur les mêmes variables : la météorologie (pluie, vent, pression, température et rayonnement), les eaux de surface (rivières en climat humide ou mares en climat plus aride), la hauteur des nappes et leur qualité. Sur les sites intensifs locaux, aux variables mesurées ci-dessus, s’ajoutent de mesures de l’infiltration de l’eau dans le sol (humidité du sol sur 2 mètres), de l’évapotranspiration (des arbres, des cultures ou des sols nus) notamment via des tours à flux et du développement de la végétation (biomasse, hauteur, flux de sève). Au total, le dispositif représente près de 280 sites de mesures (850 capteurs) qui enregistrent plus de 2500 mesures à l’heure dans 4 pays.

Partners and further information

AMMA-CATCH is led by the Institut des géosciences de l’environnement (IGE), Grenoble, in collaboration with Géosciences environnement Toulouse (GET) and Hydrosciences Montpellier (HSM). The observatory has African partners in Benin (Abomey Calavi University  and Parakou University, Direction générale de l’Eau), Niger (Abdou MoumouniUniversity, Maradi University and Zinder University), Mali (Université des Sciences, des Techniques et des Technologies, Bamako) and Senegal (Cheikh Anta Diop University, Dakar and ISRA/CRZ).

The observatory was labeled Observatoire de Recherche en Environnement in 2002, Service national d’observation (SNO) since 2005 and obtained the IRD South label in 2015. AMMA-CATCH is part of the OZCAR-RI since its creation in 2017 and receives recurrent financial supports from IRD, CNRS-INSU, as well as Observatoires des Sciences de l’Univers (OSUG, OREME, OMP).

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