Modeling and analysis of collective management of water resources

Abstract. Integrated Water Resources Management (IWRM) recommends, among other things, that the management of water resources systems be carried out at the lowest appropriate level in order to increase the transparency, acceptability and efficiency of the decision-making process. Empowering water users and stakeholders transforms the decision-making process by enlarging the number of point of views that must be considered as well as the set of rules through which decisions are taken. This paper investigates the impact of different group decision-making approaches on the operating policies of a water resource. To achieve this, the water resource allocation problem is formulated as an optimization problem which seeks to maximize the aggregated satisfaction of various water users corresponding to different approaches to collective choice, namely the utilitarian and the egalitarian ones. The optimal operating policies are then used in simulation and compared. The concepts are illustrated with a multipurpose reservoir in Chile. The analysis of simulation results reveals that if this reservoir were to be managed by its water users, both approaches to collective choice would yield significantly different operating policies. The paper concludes that the transfer of management to water users must be carefully implemented if a reasonable trade-off between equity and efficiency is to be achieved.