Contrasted land-surface processes along the West African rainfall gradient - Monsoon Multidisciplinary Analysis (AMMA) : an integrated project for understanding of the West African climate system and its human dimension

L. Seguis (1) , N. Boulain (1) , B. Cappelaere (1) , J.M. Cohard (2) , Guillaume Favreau (1) , Sylvie Galle (2) , A. Guyot (3) , Pierre Hiernaux (4) , Éric Mougin (5) , C. Peugeot (1) , D. Ramier (6) , Josiane Seghieri (1) , Franck Timouk (5) , Valérie Demarez (5) , J. Demarty (1) , Luc Descroix (2) , Marc Descloitres (2) , Manuela Grippa (7) , F. Guichard (8) , B. Kamagate (9) , L. Kergoat (10) , Thierry Lebel (2) , Valérie Le Dantec (5) , M. Le Lay (11) , Sylvain Massuel (12) , V. Trichon (13)

1 HSM - Hydrosciences Montpellier
2 LTHE - Laboratoire d'étude des transferts en hydrologie et environnement
3 TIMA - Techniques de l'Informatique et de la Microélectronique pour l'Architecture des systèmes intégrés
4 LMTG - Laboratoire des Mécanismes et Transfert en Géologie
5 CESBIO - Centre d'études spatiales de la biosphère
6 Cerema Direction Ile-de-France - Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Direction Ile-de-France
7 GET - Géosciences Environnement Toulouse
8 CNRM - Centre national de recherches météorologiques
9 Sciences et Gestion de l'Environnement
10 INS - Institut de Neurosciences des Systèmes
11 EDF R&D STEP - Simulation et Traitement de l'information pour l'Exploitation des systèmes de Production
12 UMR G-EAU - Gestion de l'Eau, Acteurs, Usages
13 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement

We review the main results of land-surface studies obtained in the three sites of the long-term observing system AMMA-CATCH. Runoff in the Sahel enhances the variability of energy partitioning between non-infiltrative areas where sensible heat is dominant and infiltrative areas where soil water availability increases the latent flux. In terms of water resources, an increase in runoff over the past 50 years, already reported for the exoreic Sahel, was revealed in the endoreic Sahel. In the Sudanian domain, the subsurface origin of streamflow could explain its decrease over the same period.

Keywords: energy fluxes; runoff; groundwater; Sahel; Sudanian climate; water resources

Domains: Sciences of the Universe [physics]; Continental interfaces, environment; Earth Sciences; Hydrology; Geomorphology

L. Seguis, N. Boulain, B. Cappelaere, J.M. Cohard, Guillaume Favreau, et al.. Contrasted land-surface processes along the West African rainfall gradient - Monsoon Multidisciplinary Analysis (AMMA) : an integrated project for understanding of the West African climate system and its human dimension. Atmospheric Science Letters, 2011, 12 (1), pp.31-37. ⟨10.1002/asl.327⟩. ⟨ird-02153235v2⟩