Reliability-based optimal design of water distribution networks under uncertain demands using cross-entropy method

Abstract

The performance of water distribution networks (WDNs) is often measured in terms of the reliability in meeting its demands. In this paper, a methodology based on cross-entropy (CE) is presented for optimal design of WDN by considering the uncertainty in nodal demands. The nodal demands are considered as random variables and their associated uncertainties are represented by normal distributions. The CE-based methodology is applied for two case studies, namely, two-loop WDN and Hanoi WDN design under uncertain nodal demands, and the solutions are compared with deterministic model solutions. It is found that the CE method is an attractive alternative technique for optimization of the WDNs that involves discrete diameters as decision variables. Also, the presented methodology provides a mechanism to incorporate network reliability into the optimal design of WDNs and helps to analyse the tradeoffs between system reliabilities and their associated costs.