ABSTRACT
The scarcity of new projects due to an obviously declining profitability, as well as the occurrence of new constraints for water management increasingly connected with environmental problems, called for the need to take an indepth look at economic calculations regarding the management of hydraulic valleys. The search for the economic value of these new power plants, marginal compared with the overall generating facilities, or the search for the cost of these new constraints, led to the development of much more refined management methods, resulting notably in the working out of meteorology and hydrology, and with the random factors of power plant availability.
