A Multi-Objective Optimization Approach for Water Pipes Renewal Planning

Water utilities ensure delivery of water to consumers through pressured network consists of several hydraulic components: tanks, reservoirs, pipes, valves and pumps. According to technical and economic factors, right maintenance policy must be applied to enhance the hydraulic performance and the reliability of the water network. With the help of a multi-objective approach based on Pareto ranking and Genetic Algorithm, we propose a decision support model. Using Modified Genetic Algorithm and hydraulic simulation, the approach discussed in this paper ensures works scheduling on pipes and availability of financial resources in the right time and way. The model is based on forecasting pipes failures and evaluating futures maintenance costs. Two indexes are used to measure the hydraulic deficiency in the water network after a failure occurrence. They measure the undelivered water quantity and the number of unsupplied nodes according to unavailability of a considered pipe during the peak demand period. Both permit to classify pipes in order to identify critical ones. Feasible solutions are assessed according to economic and technical objectives. The model proposes solutions that enhance reliability of water distribution network and reduce breaks occurrence, giving so better satisfaction to consumers.