Abstract
The notion of drought is most often associated with the aridity of landscapes andvegetation. But a green landscape can hide a frequent imbalance between wateravailability and the quantity necessary to maintain rivers in a suitable state, tosatisfy different water needs. This is the case, for example, in the French regioncalled New Aquitaine. Regularly, "drought" crisis committees are set up there tolimit water use through administrative constraints, which is technically difficultand costly for many, and with an overall unsatisfactory situation from rural areas tothe coast. But in summer, water consumption is mainly due to irrigation. Somewater resource managers have consequently set up an original non-linear waterpricing system for irrigation to achieve several objectives: above all, to limit waterconsumption in order to respect a minimum flow rate in rivers, to anticipate watersupply-demand imbalances before agricultural plantations are made, to allocatewater to the users who value it best, to recover water supply costs, to be transparentand sufficiently simple in its application to be acceptable. In this chapter, wepropose to describe one of such original pricing systems, as well as some of its mainmathematical properties and its practical interests