The central theme of research concerns the relationship between agriculture and water resources. The synthesis is organized in two parts. The first is devoted to the integration of agricultural issues in watershed management and agroecological practices in France and Brazil. In France, we are interested in agricultural pollution, their control and ownership of agroecological practices by farmers. In Brazil, we analyze the participation of farmers in the watershed management for resource sharing and to reduce impacts on water quality. A production system better integrating ecological services provided by soil biological activity (conservation agriculture) is subject to a specific analysis on ecological and agronomic interests and geographical spread. The second part is devoted to the distributed hydrological modeling to assess the variability factors of water flows and pollutants across watersheds. In western France, the model is applied to determine the effects of crop sequences and practices that are associated with the quality of water from three watersheds. In Sudano-Sahelian Africa, the model is used to evaluate the impact of climate variability on runoff from a large watershed.
