Emergency Management of Water Distribution Systems: the Nodal Demand Control

During emergency condition (e.g., pipe burst), an appropriate management of Water Distribution Systems (WDS) is required. Critical events often cause service failures, because the head in some nodes of the network (critical nodes) results inadequate to guarantee the optimal supplying. In this paper, a methodology based on the nodal demand control, is proposed. In this work the purpose is to increase the head, and hence the flow rate actually delivered, at critical nodes (i.e.: hospitals, vulnerable customers, etc.) to avoid or minimize disservices during the time between the failure and the repair. In fact, a burst in a pipe generally causes the isolation of a portion of the network such that the circulating flow along pipes changes and this causes the reduction of head in some nodes. The proposed methodology is based on the nodal demand control by managing the effective delivered flow rate using a Pressure Driven Analysis (PDA) approach. This is possible by operating on control valves and by identifying the nodes where the pressure control should be performed. Those control nodes are chosen by the analysis of sensitivity matrices and the Max-Sum Method (Bush and Uber, 1998; Fiorini Morosini et al., 2014). The case study shows the results obtained for the real network of Cosenza, a town in the South of Italy.