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Communication incl. Poster: BibTeX citation key:  Boulain
Boulain, N., Cappelaere, B., Ramier, D., Demarty, J., Fontaine, S., Issoufou, B.-A., Descroix, L. & Seghieri, J. 2009. Field and model results from eco-hydrological studies in AMMA-Niger. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: roussot 2009-11-04 17:31:57
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Categories: Land surface processes, Water cycle
Keywords: Vegetation
Creators: Boulain, Cappelaere, Demarty, Descroix, Fontaine, Issoufou, Ramier, Seghieri
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Abstract
Our study aims at the understanding of relationships between vegetation, climate and hydrological processes in the Wankama pilot watershed, in Sahelian Niger. The Wankama watershed is an intensive observation site of the AMMA program (http://www.amma-international.org/). Since 2005, the surface response to rainfall variability is continuously monitored through a vegetation survey and the recording of energy and water cycles by eddy correlation and soil moisture stations. Results point to the dominant role of water in the energy cycle variability, be it seasonal, interannual, or between land cover types. Rainfall is responsible for nearly as much seasonal variations of most energy-related variables as solar forcing. Temporal rainfall distribution also has an impact on the development of vegetation and thus on evapotranspiration and carbon uptake with a clear difference between the “natural” vegetation (fallow) and the crop vegetation. Vegetation development in the fallow was found to depend more on rainfall distribution along the season than on its starting date. A quite opposite behaviour was observed for the crop vegetation: the date of first rain appears as a principal factor of millet growth. Carbon flux exchanges are well correlated to vegetation development. Rain-season evapotranspiration is nearly always lower at the crop site. Higher soil moisture at this site suggests that this difference arises from lower vegetation requirements rather than from lower infiltration / higher runoff. These plot scale results are used to support ecohydrological modelling at the catchment scale. Simulations performed with the abc-treegrass model are compared with the 2005-2007 field measurements.
Added by: roussot