Instruments économiques et gestion de l'eau d'irrigation en France

Notwithstanding water-abundance in France, imbalances between water demands and availabiblity which cause conflicts between different categories of users, are likely during periods of low river flow. Accordingly, as water becomes a scarce resource, it can no longer be regarded as a free good, but as an economic good. Within the context of water being a limited resource, attempts are being made to induce farmers to reduce their water consumption through the development and implementation of economic instruments such as water markets, rationing (or quotas) and appropriate water pricing. Market mechanisms cannot function efficently without an appropriate legislative framework. However, the French laws of 1964 and 1992 and European regulations define principles for effective water management. The water law of 1992 stresses the unity of the water resources, requires water to be metered, and defines areas for negociation. Its implementation has spurred an interest in economic incentive instruments and their requirements and limitations. Water pricing : theoretically, water pricing can be employed as a demand-management incentive if the following necessary conditions are met. Quotas : the use of a quota system can guarantee a desired reduction of water consumption, but it is costly to implement. Since a quota cannot be modified annually, it suffers from rigidity and provides no incentive to save water. Water markets : a water market is an allocation mechanism based on the trading of water rights granted initially to the various participants. Water pricing and quota systems are in use in France. These instruments are not incompatible and are likely to be complementary. / En France, la loi sur l'eau (1992) affirme l'unicité de la ressource en eau, impose des instruments de comptage, donne un cadre de négociation à travers les Schémas Directeurs d'Aménagement de Gestion des Eaux (SDAGE) et propose des lieux de concertation (Commissions Locales de l'Eau). Sa mise en application renouvelle l'intérêt pour les instruments incitatifs de gestion (tarification, quota, marché de l'eau), leurs conditions de mise en oeuvre et leurs limites. En France, dans le domaine de l'eau agricole, tous les types d'instruments économiques sont présents à l'exception des marchés de l'eau. Ils sont mis en oeuvre en fonction des conditions de mobilisation de la ressource et des caractéristiques de la demande. On rencontre ainsi le prélèvement de redevances par les agences de bassin, sur la base du principe préleveur-payeur mais avec un niveau sensiblement inférieur au coût d'opportunité de l'eau dans son site et avec des exonérations sous certaines conditions ; une tarification dont les objectifs peuvent être l'équilibre budgétaire du gestionnaire, la participation aux investissements, la durabilité des ouvrages et une incitation à économiser l'eau.