Reliability Based Design of Water Distribution Network (WDN) Considering the Reliability of Nodal Pressures

Optimization of water distribution networks (WDN) has been one of the main challenges of researchers for many years. By paying one-dimensional attention to the minimization of WDN costs, one would ignore efficiency factors such as the reliability in delivering nodal demands with desired pressure. By considering the nodal pressure satisfaction as a rigid constraint, the maximum reliability will occur not reflecting the influence of a minor reliability reduction in the system cost. Hence, there is a need for designers and decision makers to have a landscape of the system performance, considering the flexible permissible nodal pressure and its effect on the system cost. In this paper, honey-bee mating optimization (HBMO) is applied in a benchmark WDN (two-loop) problem. The objective is minimization of cost with respect to different levels of reliability in the system during the operational period. Because in WDNs the decision variables are in a discrete domain, a minor decrease in the reliability of nodal pressure can yield a major cost reduction. Furthermore, by, considering different nodal pressure reliabilities, critical nodes of the network can be determined.