Avaliação de intervenções hidráulicas na bacia do rio Gramame-PB com o uso das técnicas de análise multiobjetivo e multicriterial.

Abstract

The growing environmental changes and social impacts imposed by human actions and the need of reverting or minimizing their harmful aspects have resulted, over the last years, in the reformulation of the planning and management of water resources. Nowadays they look for including, in the processes of hydraulic interventions impacts evaluation, aspects that go beyond the economical analysis itself, which aims at the maximization of the economical benefits. That is, a more realistic analysis, which takes into account several dimensions, such as social, environmental, political, among others, has been searched. This study aims to look for, to structure, to process and to analyze informations to give support to decision makers about the best choices that can be taken among possible hydraulic intervention actions, under a multiobjective and multicriteria analysis view, for the increase of the Gramame river basin water resources availability, which is located in the south coast of the Paraíba state, in order to minimize future water use conflicts. The efficiency and sustainability indexes selection try to portrait the social-economical and environmental aspects that are used as judgment criteria in a multicriteria analysis. The indexes were determined via the application of a multiobjective monthly based multi annual optimization model, which is based on linear programming and allows one to perform a river system study in an integrated way, which includes reservoir, irrigated perimeters, pipes and urban water supply. The PROMETHEE II method was used for the selection and ranking the best system hydraulic interventions, having in mind different preferences possibilities. From the obtained results in the optimization process it was possible to verify that the practice of the irrigation can result in financial losses, once the current water system doesn't guarantee the fulfillment of their water demand supply in none of the considered perimeters and scenarios. The obtained rankings for the alternatives varied according to the adopted preferences. Alternative 1 (no hydraulic intervention) was selected when the environmental criteria was privileged, alternative 8 (construction of reservoirs at Mumbaba and Gramame rivers and provide water transposition from Abiaí-Papocas rivers to Gramame's Water Treatment Station) was selected when social criteria was privileged and alternative 6 (construction of reservoir at Mumbaba and provide water transposition from Abiaí-Papocas rivers to Gramame's Water Treatment Station) was selected when economical criteria was privileged. Taking into account all analysis performed, the best ranked alternatives were 1 and 8, which were ranked in the first place with 42 %. The results supplied by the multi-objective optimization model and the multicriterial analysis may provide important insights regarding to the operational subjects and the implantation of hydraulic interventions for the decision makers through the consideration of the system behavior information and the different judgments criteria.