Effects of pressure dependent analysis on quality performance assessment of water distribution networks

Water network performance is defined as the ability to deliver a required quantity of water under sufficient pressure and an acceptable level of quality. A sound performance indicator is a powerful tool for more efficient management of water systems. This paper introduces a methodology for performance assessment of water distribution networks based on quality parameters (such as residual chlorine, water age, etc.) and the head driven simulation method (HDSM). For hydraulic analysis of water networks a pressure dependent simulation model is used. This model is able to predict the hydraulic behavior of the system more realistically, especially during abnormal and critical conditions (e.g., outage of pumps and reservoirs, pipe breaks, leakage, excess demands, etc.). Also, a discrete-volume element method (DVEM) is applied for the analysis of water quality parameters.
In the next step, using penalty curves based on the standard codes for quality parameters, the quality performance of the system is assessed. By evaluating a test network, the application of the new methodology is presented. The results are also compared with the widely used water quality simulator of EPANET 2 software, which uses the demand-driven simulation method (DDSM) as its hydraulic simulation engine. The DDSM models consider fixed demands regardless of nodal pressure variations. Consideration of HDSM leads to different pipe velocities, and therefore, different values for quality parameters. The results showed that the introduced procedure can help to assess the performance of quality parameters in water distribution networks more realistically than the existing demand-driven simulation based models.