Improving the quality of Pareto optimal solutions in water distribution network design

This paper proposes five methods for improving the quality of Pareto optimal solutions of multiobjective optimal water distribution network (WDN) design problems: (1) three warm initial solution methods, (2) the postoptimization method, and (3) the guided-search method. The five methods were demonstrated through resilience-based design of the Hanoi network. The guided-search method, considering the reasonable range of decision variables, was identified as the best method with respect to the nondomination and diversity of the obtained Pareto solutions. Then, the effect of considering known initial solutions (e.g., least-cost solutions obtained from single-objective optimal design) on the final Pareto solution quality was investigated using the guided-search method. Finally, the guided-search method was compared with five multiobjective optimization algorithms widely used in the WDN research community through the resilience-based design of well-known benchmark WDNs (i.e., two-loop, Hanoi, Balerma, and P-city).