Evaluation of Sustainability Index of Water Distribution Network Using Demand-Driven and Pressure-Driven Analysis

This study presents a sustainability analysis of optimally designed water distribution networks (WDNs) under hydraulic failure situations using demand-driven analysis (DDA) and pressure-driven analysis (PDA). Two benchmark WDNs and their discrete designs are considered for this purpose. Hydraulic uncertain conditions are generated as a simultaneous variation of nodal demands and roughness coefficient using Monte Carlo simulation considering two different coefficient of variation (COV) values. The nodal performance of these networks is estimated using average nodal reliability (ANR) and average nodal vulnerability (ANV) metrics. The hydraulically efficient and critical nodes are ascertained from these measures, which are essential for proper operations and maintenance. Apart, the system performance measures, such as average system reliability (ASR), average system resilience (ASRes), and average system vulnerability (ASV), are evaluated. Since, all these performance measures resulted in different conclusions, an aggregate performance measure, the sustainability index (SI), is considered. Unlike other studies, the SI of WDN under uncertain scenarios and subsequently the average sustainability index (ASI) is measured. The evaluation of ASI that quantifies the network’s sustainability is intuitive and helps to select a better design from a set of optimal designs with similar costs and different diameter sets. Further, the study compares DDA and PDA analysis, demonstrating no-flow, full, and partial-flow situations. The statistical variation of the results is also illustrated. DDA underestimated the network hydraulics, which became faultier with the increase in uncertainty. The underestimation of hydraulic parameters misleads design, operational, and maintenance decision making. Thus, the study suggests PDA as the most reliable model for performance analysis and the optimal design of WDNs.

The present study details the performance and sustainability analysis of optimally designed water distribution networks under hydraulic failure situations using demand-driven analysis and pressure-driven analysis. The hydraulic efficient nodes, critical nodes, and the best and least performing optimal designs, which are preliminary needs of any water supply policies, are determined. The hydraulic efficient nodes sustain the failure situations, whereas the critical nodes are key failure zones that need special attention during maintenance work. The sustainability index evaluated in the study will be helpful in clearly distinguishing the best designs from the given alternate options. The detailed comparison of demand-driven analysis and pressure-driven analysis in assessing the performance of water distribution networks under hydraulic uncertainties demonstrated that demand-driven analysis underestimates the water distribution network’s performance. Further, the performance assessment with demand-driven analysis became faultier with the increase in uncertainty. Consequently, the recovery cost for uninterrupted water supply policies would be overestimated using demand-driven analysis results. Thus, it is advisable to use pressure-driven analysis as an economical and reliable model for the design, performance, operation, repair, or maintenance works of water distribution networks.