Demand-Driven Spatiotemporal Variations of Flow Hydraulics and Water Age by Comparative Modeling Analysis of Distribution Network

Abstract

Distribution network modeling is proposed to investigate and manage water quality variations in a distribution network. Common practice in the modeling relies on pipe network simplification through skeletonization and uses water demand patterns that are often generalized or derived from historical monthly water usage records. Because automatic water meter reading (AMR) and the supervisory control and data acquisition (SCADA) technologies are widely used, it is possible now to explore the hydraulic complexity in the network. Processes such as stochastic and pulse water demand on solute transport characteristics can be investigated. Fidelity and appropriateness of network modeling by network simplification can be quantified. In this paper, the modeling performance on network simplification are assessed using real-time water demand measurements and comparative network simulations for an independent segment of a large water utility in the United States. An all-pipe all-demand (APAD) model and an hourly demand variation curve (HDVC) demand model are simulated for the same network operations. Results show the prevalence of intermittent and pulse water demand particularly in network perimeters and dead-end branches. The results also highlight different node hydraulic properties such as R, water age, and flow oscillation when water demand in the APAD model is replaced by HDVC-based time-continuous generalized demand patterns. The degree of such difference varies specific to the distribution network configurations such as H-loop, branches, and dead-ends. These additional insights provide further understanding of the varying flow properties and their impacts on the movement of water parcels in pipe configurations. It is suggested that APAD network simulation be used for accuracy-demanding water quality simulation.