Evaluating Flexibility in Water Distribution System Design under Future Demand Uncertainty

Performance of water distribution systems (WDSs) is highly dependent on consumer water demand that has to be met with adequate pressure. With uncertain future water demand due to the effect of rapid urbanization and climate change, WDSs may underperform or end up being overdesigned because of the long-term unforeseen future conditions. Long-term planning of WDS therefore requires strategic, cost-effective, and sustainable design intervention investment across the entire planning horizon that is uncertain in nature. However, making the most appropriate decisions on such intervention measures that keep up the performance of WDS under uncertainty is a challenge. This paper illustrates the importance of flexible WDS design under uncertain future water demand. The methodology has been tested on the New York Tunnels and the Anytown network interventions in the long-term planning. The approach is compared with the traditional deterministic intervention plans. The analysis results demonstrate that there is potential WDS performance value obtained when flexible design approach is adopted rather than the conventional deterministic practice. (C) 2014 American Society of Civil Engineers.