Otimização de sistemas de abastecimento de água considerando variáveis as condições de contorno do projeto.

Abstract

For decades, the water supply system design was held by the traditional methods of Hardy-Cross and Fictitious Sectioning. Only since the end of the sixty decade, with the use of microcomputers it was possible the application of the mathematics optimization techniques in the economical design of the water supply systems, in order to obtain the minimal total cost. Based on these techniques, many methods of optimisation in the water supply system appeared. However, in all of them the parameters of the project's boundary conditions are considered invariable during all its range. It does not take into account the variation that can occur in the following aspects: population, internal roughness pipe walls, daily water consumption, project's average demand, number of pumping hours and in the economical factors, since the moment of the project's implantation until the end of its exploration period. It was also verified that in these methods the costs effects of the structural concrete of the elevated reservoir necessary for the water supply are not taking in account. Therefore, it was proved the necessity of studying these parameters variation and incorporating them in the process of the economical water supply system projects. In this work, deeper studies about the variation of these parameters along the time were carried out, in which some formulas were developed or adapted for roughness calculation, head loss, population, project average demand, annual number of pumping hours and economical factors. These studies were incorporated to the method of systems optimization developed with base on the mathematics model of the non-linear programming, in which the variation of these parameters are considered during all the project range. The costs effects of the elevated reservoir were also studied in the optimisation process. The solution of this method was held by a computation program developed in this work, which is able to carry out the system optmization. The method was applied in the networks economical system design in the Bessa district (Joao Pessoa -PB) and in the city of Itotoro (Bahia). It was proved that the method and the computation program developed in this work were efficient in the determination of the total optimum cost of the project. It was possible to conclude that the variation effects of the parameters of the project's boundary conditions should be considered in the optimization of the water supply system, taking into account that they have meaningful influence in the design. Finally, it was observed that the concrete cost of the elevated reservoir can be included in the optimization process.