Topological Placement of Quality Sensors in Water-Distribution Networks without the Recourse to Hydraulic Modeling

The detection of contaminant intrusion into a water-distribution network (WDN) is a difficult issue due to uncertainty related to the type of injected contaminant, source location, and intrusion time. The placement of water quality sensors has received increasing interest in the last years, and it still represents an open problem and a great challenge for researchers and utilities. Efficient numerical techniques are needed to support any contamination warning system (CWS) design. These require a well-calibrated hydraulic model of the WDN and a great deal of information, both of which are often unavailable to water utilities. In addition, as the size of the WDN increases, the choice of effective sensor placement becomes a computationally intractable problem. This paper introduces a methodology to support water utilities in the design of an effective CWS without any use of hydraulic information, but just exploiting the knowledge of the topology of the WDN. To ensure a complete coverage of the network, the method relies on a priori clustering of the WDN and on the installation of quality sensors at the most central nodes of each cluster, selected according to different topological centrality metrics. The procedure is tested on a benchmark network and on a real WDN serving a town close to Naples, Italy. The solutions obtained with topological criteria are effective in terms of detection time, detection likelihood, redundancy, and population exposed through ingestion.