A bargaining model to simulate negotiations between water users

The French water law of 1992 requires that regulations on water use and wat er management be negotiated collectively and locally in each river sub-basi n. Decision-makers therefore need new tools to guide the negotiation proces s which will take place between water users. A formal computable bargaining model of multilateral negotiations is applied to the Adour Basin case, in the South West of France, with seven aggregate players (three "farmers", tw o "environmental lobbies", the water manager, the taxpayer) and seven negot iation variables (three individual irrigation quotas, the price of water, t he sizes of three darns). The farmers' utility functions are estimated with hydraulic and economic models. A sensibility analysis is conducted to quan tify the impact of the negotiation structure (political weights of players, choice of players...) on game outcomes. The relevance of the bargaining mo dels as negotiation-support tools is assessed.