Characterizing the effects of water distribution system topology modifications on its dynamic behaviour through connectivity metrics

Water distribution networks (WDNs) are complex combinations of nodes and links and their structure has an impact on their behaviour, considering both quantitative (i.e. related to pipe flows and nodal pressures) and qualitative (i.e. related to water age and quality) aspects. The complexity of WDNs has been the basis of several studies that have resorted to the graph theory to relate connectivity properties to system behaviour (e.g. its reliability and water age/quality), evaluated under the assumption of steady-state conditions. Within this framework, in recent years the tendency toward reducing network interconnection through the closure of isolation valves has emerged, mainly to (i) facilitate its monitoring and management, and (ii) increase flow velocity and reduce water age. However, changes in the topology of a network can affect not only aspects evaluated under the assumption of steady-state conditions, but also its dynamic behaviour. Based on these considerations, the present study investigates whether some metrics derived from graph theory, already applied in the context of networks’ steady-state analyses, can also provide useful indications for assessing the effects of changes in the topological structure, which could be consequences of branching operations, on the dynamic response of a network subjected to users’ activity. The analyses highlight that connectivity metrics can reflect the pressure dynamic behaviour of the hydraulic systems and support in their macroscopic understanding during design and management operations. Thus, their application can be effectively extended from the steady-state to the dynamic framework.