Cappelaere Bernard auteur aut IRD Descroix Luc auteur aut IRD Lebel Thierry auteur aut IRD Boulain Nicolas auteur aut IRD Ramier David auteur aut IRD Laurent J. P. auteur aut IRD Favreau Guillaume auteur aut IRD Boubkraoui Stéphane auteur aut IRD Boucher Marie auteur aut IRD Moussa I. B. auteur aut IRD Chaffard Véronique auteur aut IRD Hiernaux P. auteur aut IRD Issoufou H. B. A. auteur aut IRD Le Breton E. auteur aut IRD Mamadou I. auteur aut IRD Nazoumou Y. auteur aut IRD Oi Monique auteur aut IRD Ottle C. auteur aut IRD Quantin Guillaume auteur aut IRD text journalArticle eng text/pdf born digital access Among the three sites distributed along the West African latitudinal gradient in the AMMA-CATCH observation system, the experimental setup in the Niamey area of south-west Niger samples the cultivated Sahel environment, for hydrological, vegetation and land surface processes. The objective is to investigate relationships between climate, land cover, and the water cycle, in a rapidly changing semiarid environment. This paper first presents the main characteristics of the area, where previous research, including the EPSAT and HAPEX-Sahel experiments, had evidenced a widespread decadal increase in water resources, concurrently with severe drought conditions. The specifics of AMMA-CATCH research and data acquisition at this site, over the long-term (similar to 2001-2010) and enhanced (similar to 2005-2008) observation periods, are introduced. Objectives and observation strategy are explained, and the main characteristics of instrument deployment are detailed. A very large number of parameters - covering rainfall, vegetation ecophysiology, phenology and production, surface fluxes of energy, water vapour and CO2, runoff and sediment, pond water, soil moisture, and groundwater - were monitored at local to meso scales in a nested structure of sites. The current state of knowledge is summarized, connecting processes and patterns of variation for rainfall, vegetation/land cover, and the terrestrial hydrologic cycle. The central role of land use and of its spectacular change in recent decades is highlighted. This paper provides substantial background information that sets the context for papers relating to the south-west Niger site in this AMMA-CATCH special issue. specialized Land cover change Semiarid Water resources Ecohydrology Savanna vegetation Observation system 062 082 375 1-2 34-51 2009 0022-1694 https://www.documentation.ird.fr/hor/fdi:010048250 10.1016/j.jhydrol.2009.06.021 0022-1694 [F B010048250] https://www.documentation.ird.fr/hor/fdi:010048250 https://www.documentation.ird.fr/intranet/publi/2009/10/010048250.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2009-11-09 2017-08-23 fdi:010048250 fre