Probabilistic analysis and evaluation of nodal demand effect on transient analysis in urban water distribution systems

The implementation of nodal demands in current transient modeling and analysis in the urban water distribution system (WDS) is usually based on steady-state conditions or empirical-based approximations, lacking for appropriate evaluation and scientific guidance of the nodal demand effect on transient modeling and analysis for accurately reproducing transient responses. This paper develops a probabilistic analysis and evaluation framework based on Monte-Carlo simulation (MCS) and global sensitivity analysis (GSA) methods for prior-known evaluation of transient nodal demand effects in WDS. An expression of the demand impact factor (DIF) is first proposed for indicating the influence of nodal demand effect based on a Lagrangian nodal demand model and implemented in the developed evaluation framework. Parameter sensitivity analysis is then conducted to evaluate the relevance and importance of the DIF to transient modeling and analysis in WDS. The results indicate that the DIF is highly relevant to the inherent attributes and initial steady state of the system, which can thus be used to facilitate the prior-known evaluation of the importance and influence of nodal demand effect in WDS. To demonstrate the application procedure and the applicability of the proposed probabilistic method, a realisticWDS is adopted for numerical investigation. The application results and analysis confirm the effectiveness and improvement of the developed method in this study on the guidance of accurate transient modeling and analysis under the influence of nodal demands in WDS.