Implementation of Pressure Reduction Valves in a dynamic water distribution system numerical model

The analysis of water distribution networks has to take into account the variability of users water demand and the variability of network boundary conditions. In complex systems, e.g. those characterized by the presence of local private tanks and intermittent distribution, this variability suggests the use of dynamic models that are able to evaluate the rapid variability of pressures and flows in the network. The dynamic behavior of the network also affects the performance of valves that are used for controlling the network. Pressure Reduction Valves (PRV) are used for controlling pressure in the network and for avoiding excessive pressure in the periods of low demand and reduce leakages. When network is characterized by highly variable demands, the PRV outlet pressure can be seen to fluctuate significantly with minor demand changes in the network. The related transient phenomena propagate through the network and may result in water quality problems, unequal distribution of resources among users, and premature wear of the pipe infrastructure. A model was developed in previous studies and demonstrated to provide reliable results in the analysis the behavior of intermittent networks. The model is able to simulate the initial filling of the network and the dynamic behavior of the network. The model was applied to a district of Palermo network (Italy) characterized by intermittent distribution and the presence of PRVs. The district was monitored and pressure as well as flow data were available for model calibration.