Résumé
In most temperate regions, water is used mainly for irrigation purposes, while qualitative and quantitative problems are generally linked. This leads to different conflicts inside the agricultural sector, between the domestic, industrial and agricultural sectors and between these sectors and those worried by the evolution of the natural environment. In Europe, generally, water does not belong to anybody, hence the impossibility to create a water market and then a water resale market. Moreover some constraints of the irrigation management companies or associations are to be taken into account. Preliminary studies showed that in this context non linear pricing could lead to a more efficient water usage, when water supply and demand remain uncertain. By introducing a degree of freedom in the pricing formula, as for example a subscribed volume in autumn or spring, not necessarily equal to the consumed water in summer, it seems possible to: Make just the necessary information revealed, in order to anticipate summer water demand and then future conflicts, before their breakout, so that conflicts may be lessened; Satisfy constraints on the available water volume; Conduce to a reduction of water consumption, and allow a strict respect of ecological minimum water flow; Satisfy constraints on the agricultural production, farmers revenue, and on the water user association budget. This presentation shows the potentiality and the difficulties linked to such a solution, in a stochastic environment.