Peak Demand Assessment and Hydraulic Analysis in WDN Design

Abstract

This work aims to investigate the extent to which demand assessment at fine temporal scales can be useful in the design of a small water distribution network (WDN). To this end, the peak demand assessed thorough the traditional design approach (DA1), based on the amplification of yearly average demand and aimed at obtaining an hourly peak demand estimate, is compared with those obtainable through plumbing system design procedures (DA2) and demand pulse generation models (DA3), both conceived at a fine temporal scale. A further objective of this work is to analyze the WDN hydraulic behavior in the peak hour in terms of nodal pressure heads. In this context, the snapshot steady flow modeling (SFM) with nodal demands assessed through DA1, which is usually adopted for WDN design, is compared with the unsteady flow modeling (UFM) with trend of nodal demands assessed through DA3. Overall, the results of this work show that, when applied to WDNs serving few inhabitants, the hourly demand estimate provided by DA1 can be much smaller than the estimates of DA2 and than the maximum values of DA3, which are instead in quite good agreement. Furthermore, UFM+DA3 can spot service pressure deficits in peak demand scenarios, which are unidentifiable through SFM+DA1.