Résumé
The viability of irrigated systems in the Senegal River Valley is being brought into question today due to their under-utilization. We assume that their viability depends on the way their different components behave and interact. A field work was designed to grasp the diversity of individual and collective behaviors and interactions encountered. This led to the development of a multi-agent system model, a kind of virtual irrigated system, with a special focus on rules in use for access to credit, water allocation and cropping season assessment as well as organization and coordination of farmers. This model is then used to explore consequences of different sets of individual and collective rules. Viability of simulated irrigated systems appears to be linked to none of them. This result refers to the question of relations between individuals and groups for resource management as well as multi agent systems.