Environmental and economic optimizatian techniques applied to water resources integrated management

In the last two decades, a growing number of actors in charge of water resources took steps to improve their management. The purpose was generally twofold : (1) to insure preservation of the resource through space and time, and (2) to optimize exploitation processes. Several methods have been developed and applied in France and abroad. Their concept, their dimension and their technical structure vary a lot. To be fully efficient, they must be adapted to the local context and be correctly scaled to the problem at stake. This article briefly describes three of these methods built on different concept, with increasing complexity. They were implemented within the framework of an environmento-economical optimization approach, in three different contexts in terms of size, and both structural and operational characteristics. These resulted with positive impacts on the environment and on the social context, and sound balances between the different water uses could be achieved. Associated short, middle and long term economic benefits are manifold and variable. They depend among other things, (1) on the starting conditions, (2) on the characteristics of the context, and (3) on the criteria and methods used to compute environmental and exploitation values. Generally, however, economic benefits are important, and sometimes even, very important.