Modelo de otimização qualiquantitativo multiobjetivo para o planejamento dos recursos hídricos superficiais, com aplicação à bacia do rio Paraíba.

Abstract

This work presents a quali-quantitative multiobjective optimization model, based on linear programming, for planning and management of reservoirs and irrigated areas perimeters, besides other water uses, integrated system to provide optimal resources (water and land) allocation and establish optimal operational policies in riverbasin systems, The multiple water uses includes meeting the requirement of irrigation and human supplies demands, flood control, minimum regulated flows, target reservoirs volumes, optimal crop plantation area allocation and water quality parameters concentration in reservoirs and riverbeds. The water withdraw can be done at reservoirs or riverbed sections. Social and economic aspects, such as maximization of net profit and irrigated perimeter labor, are considered in the model. The nonlinearities of the objective function and the involved process, described by the constraints imposed in the optimization problem, were implemented through the use of a combined used of mathematical linearization techniques. The model has been applied to the study of two reservoirs, Epitácio Pessoa and Argemiro Figueiredo, connected in series in the Paraíba river basin, a 1220 ha irrigated perimeter and the riverbed connecting both reservoirs. The considered water demands involved human supply for the cities in the neighborhood, irrigation, regulation of river flow downstream the Acauã reservoir and meeting adopted class water quality standard parameters within the reservoirs and the considered section of the river. The following objectives were considered: minimization of water requirement deficities and some water quality parameters in reservoirs and the section of the river, meeting the reservoirs target volumes and the minimum regulated flow downstream the Acauã reservoir and maximization of net profit, labor in irrigated perimeter and dissolved oxygen water quality parameter. In order to evaluate the model response regarding computational time and results consistency, scenarios with different priority assignments to the objectives were idealized. The results have shown that the considered objectives were met according to the preestablished constraints and priorities for each scenario (showing the model performs a multiobjetive analysis). The urban water demand is fulfilled without any failure. Agricultural activities can be developed without compromising the fulfillment of urban water requirements. On the other hand, the requirement of certain water quality parameters may compromise agricultural activities, if it is not implanted a sewer treatment system. The attained results may provide subsidies to decision making regarding the establishment of operational rules or water right processes.