Impact of problem formulations, pipe selection methods, and optimization algorithms on the rehabilitation of water distribution systems

Given the continuous aging of pipeline infrastructure buried underground, water utilities need to make a strategic plan on how to maintain the entire water distribution systems (WDSs) to ensure the required standard of supply. This paper investigates the nexus of three key factors that have a significant impact on the decision-making process of the rehabilitation plan for WDSs. The factors considered include the problem formulations, the pipe selection methods for identifying critical components of WDSs, and the multi-objective evolutionary algorithms (MOEAs). The nexus was revealed by considering all the combinations of two variants for each factor. The optimal rehabilitation problem of the Exeter network was used as a case study. Results exhibit that the problem formulation determined the range of Pareto fronts essentially, which should give the highest priority in the decision-making process. The pipe selection method played a secondary role, mainly affecting the shape of Pareto fronts. Optimization algorithms also had a considerable impact on the optimality of solutions, subject to their characteristics and parameter settings. This paper also highlights that breakthroughs need to focus on these key factors to facilitate a more cost-effective solution to the rehabilitation of large WDSs.