GALP — Complementary Usage of Deterministic and Heuristic Methods in the Optimization of Water Distribution Systems

A new optimization model for determining the minimum cost for the design of water distribution systems is described in the paper based on a combination of linear programming methodology (LP) and a genetic algorithms approach (GA). A many different heuristic algorithms have been developed in the last two decades and applied to the design of water distribution systems. Although many research efforts have been made for the sake of achieving the optimal design of the looped water distribution networks, there is still some uncertainty about finding a generally reliable method. The author of the paper is proposing a method in which the main emphasis is placed on its higher reliability of finding an optimal solution in terms of closeness to a global minimum. In this study the efficiency of GA optimization was improved through a hybrid method, which combines the GA method with a linear programming methodology. The GA method is used in the outer loop of the proposed algorithm, which is intended for decomposing a complex looped network to a group of possible branched networks. The mathematical models using LP are then set up in an inner loop for each member of this group of branched networks for their optimization. After evaluating the high number of possible branch networks (by LP which is nested in a GA fitness function), an optimal solution could be found for the original looped network.