Otimização da água do reservatório Coremas/Mãe d'Água para múltiplos usos.

Abstract

A system of two interconnected reservoirs, Coremas and Mae D'Agua, is located at south-western part of the Paraiba state, and they are fed by three rivers: Pianco, Emas and Aguiar. They, togheter, are the largest reservoir of the Paraiba state and the third largest one in the northeast part of Brazil. Their waters are used for human supply of 33 small towns, hydroelectric power generation, irrigation and fishing activities and to meet downstream water demand required from the Rio Grande do Norte state. Two irrigation sites are supplied by those reservoirs: one with 1880 ha located in the neighborhood of the reservoirs and another with 4880 ha, in the neighborhood of the city of Sousa, which is connected to the reservoir through an open channel with length of 37 Km. The aim of this work is to maximize the social and economical benefits through the choice of irrigation areas for 8 selected types of fruits and 7 selected types of vegetables and grains, as well as, to establish the monthly water release, of which the electrical power generation depends upon. The mathematical model uses a nonlinear programming method with 480 constraints that represents the physical and operational behavior of the system, including the sustainability of the reservoirs. Among the set of constraints it is worthwhile mentioning that the water balance is performed at each one of the reservoirs and the interconnected vessel principle is used to establish the reservoirs' water transfer. The analyses were performed using dry, normal and wet scenarios and different values for the reservoir initial volume. From the results one may observe that the plantation of fruits generates better net profit while growing vegetables and grains generates more human labor. The net profit that can be attained from fishing activities were the best ones when dealing with a wet scenario, reservoirs initial volume equal to 80% of their capacities and growing vegetables. The electric power generation was at their maximum capacities due to the requirement of a minimum water release to the Rio Grande do Norte state.