Operational considerations for the long-term design of water distribution systems

Water Distribution Systems (WDS) are complex systems that play a critical role in supplying water while satisfying the required levels of service (expressed as objectives and constraints). The effective interaction and execution of numerous levels of optimal control, design, and monitoring of the associated components are necessary for these massive infrastructures to operate properly. This necessitates finding solutions to a number of issues with objectives spanning vastly diverse time horizons: the long-term infrastructure design [1], the daily and sub-daily system operations [2], and the real-time control of the active elements [3]. Traditionally, these tasks have been considered separately. Yet, the centralization and coordination of the optimization of all processes provide several advantages [4]. For example, design limitations can restrict the system’s operational performance. On the other hand, a system designed without taking operations into account ignores important uncertainties and flexibility afforded by installed controllable elements. There has been an increasing interest in WDS's flexible and adaptive design [5]. However, those studies concentrated on introducing long-term design uncertainties, limited to pipe sizing, rehabilitation, and strengthening, and have not taken into account the effect of control elements on the network. This literature review investigates the shortcomings of current methodologies and highlights how they may be improved to consider uncertainties and opportunities during the long-term design of WDS that are provided by control elements. The ultimate goal is to develop robust and flexible strategies in support of the decision-making processes capable of coping with deep uncertainties associated with WDS evolving in time.