This paper deals with bicreteria (irrigation & water
quality) weekly operation of a water resource system during dry period. Two
ways of handling the problem are assessed and compared on a real case study
Numerical results are plotted on historical varies for both methods.
From the present application to the NESTE system, the conclusions are :
1) Both procedures allow the system manager to formulate operating strategies
in a rational way :
2) The system analysis approach is based on stochastic dynamic programming.
If can be efficiently used to derive optimal feedback ruses of operation and
can routinely deal with complex decisions such as limiting irrigation when
a shortage is to occur or take the risk to keep going and decrease output targets
for water quality management. At the same time, this procedure entails heavy
computing time, uneasy interpretation of the weighting coefficient between
irrigation and water quality objectives, and a rather artificial elicitation
of the global compromise.
3) The synthetic method may appear more attractive from the engineering point
of view for the following reasons :
4) Such models are designed to serve only as multicriterion decision making aids. In very dry days such as occurred in summer 1976 or 1989 in France they cannot create additional water resources... still, they can help the system manager by constant up dated multidimensional estimation of the risks that may be encountered when following different operation rotes. In the case of the NESTE system, a real-scale experiment began in 1989: in real time operation, both models worked on line as decision-making supports, and the system manager made a thorough study of the hydrological conditions when the two approaches did not agree on the same stragegy for the following week.
Reservoir operation, dynamic programming, risk management, decision making, modeling, low flow augmentation, irrigation.
Parent, E., Chercheur au Centre d'Enseignement et de Recherche pour la Gestion des Ressources Naturelles, ENGREF-ENPC, La Courtine, 93167 Noisy-le-Grand Cedex, France