Water distribution networks robust design based on energy surplus index maximization

The aim of this paper is to show that energy surplus indices, such as resilience index, besides providing a very good indirect measure of water distribution network reliability to be adopted during the design phase, represent also a valuable and effective indicator of the robustness of the network in alternative network scenarios, and can thus be profitably used in condition of future demands uncertainty. The methodology adopted consisted of (I) multi-objective design optimization performed in order to minimize construction costs while maximizing the resilience index; (II) retrospective performance assessment of the alternative solutions of the Pareto front obtained, under demand conditions far from those assumed during the design phase. Two case studies of different topological complexity were considered. Results showed that resilience index, which is one of the most effective indirect indices of reliability, represents a very good measure of robustness as well.