Résumé
The Beauce aquifer (France) is one of the few subjected to volumetric management resulting from a negotiation between farmers and the administration. Since 1999, a quota has been allocated to each of the 3,600 irrigated farms located on six administrative counties. Each year, quotas are weighted by a coefficient of reduction linked to the average piezometric level. The decrease in the level since 2003 has led to a reduction of withdrawal permission with uncertainties for the future. This paper presents an approach developed with actors to analyze their adaptations and the agronomic and economic consequences of a thus far hypothetical substantial reduction in irrigation quantities.