Demand Components in Water Distribution Network Analysis

Solving water distribution network hydraulics depends to a great extent on demand representation in the related simulation models. The classical approach of simulation models for water distribution networks (WDNs) is described as demand-driven. The demands are fixed a priori in the model as an assumption or from field observations. Recently a more realist approach to predict the hydraulic system behavior, described as head/pressure-driven, better accounts for the fact that the demands depend in some ways on head status of the network. Thus, this paper presents a comprehensive view of demands in the enhanced WDN simulation models, including considerations of human-based, volume-based, uncontrolled orifice-based, and leakage-based demands as distinct types of network outflows. The paper proposes and discusses the representation of each type of demand in a comprehensive framework that is consistent with the hydraulic principles and the specific working condition.