Résumé
The French water law of 1992 requires that regulations on water use and water management be negotiated collectively and locally in each irrigation basin. Decision-makers therefore need new tools to analyse the negotiation process which will take place between water users. A formal computable bargaining model of multilateral negotiations is applied to the Adour Basin case, with four aggregate players (three "farmers" and one "environmental lobby") and two negotiation variables (individual water quota and water charges). The farmers' utility functions are estimated with hydraulic and economic models. A sensibility analysis is conducted to quantify the impact of decision rules and of the political weights of players on game outcomes. Within a context of imperfect information on players' interests and players' rules of behaviour, these simulation results provide a better understanding of the issues at stake and highlight the coalition formation process.