A Quick Survey of the Most Vulnerable Areas of a Water Distribution Network Due to Transients Generated in a Service Line: A Lagrangian Model Based on Laboratory Tests

This paper analyses the propagation and mechanisms of interaction of a pressure wave in a looped water distribution network by means of laboratory and numerical tests. Transients are generated by the complete and fast closure of a valve, simulating an end-user maneuver, located at the downstream end section of a service line. The adequate length of the service line allows capturing each single pressure wave inserted into the network. The executed tests and successive analysis by means of a Lagrangian model (LM) highlight the effect of the network topology and the location of the transient generation point but in a more expeditious way with respect to the use of a complete transient model. The most excited part of the system is the one in close proximity of the end-user and then the corresponding service line. Within the network, pressure waves accumulate in the areas with the smallest diameter pipes. By means of the refined LM—which is able to capture the pressure extreme values occurring in the first phases of the transient—the vulnerability maps of the network are provided. Such maps identify the nodes subjected to the most severe pressure waves in terms of both frequency and amplitude. The exposure level to transients of each node is synthesized by the value of the vulnerability index proposed in this paper.