Sensor placement for leak monitoring

The goal of this chapter is to review recent developments on sensor placement for fault diagnosis in drinking water networks. Solving a sensor placement problem for fault diagnosis entails the evaluation of the diagnosis performance of a monitoring system for a certain sensor configuration. In model-based fault diagnosis the monitoring system is built upon a set of consistency indicators, which are designed based on a model of the water network, and evaluated on the measurements provided by the sensors. The diagnosis performance is usually evaluated based on the fault sensitivity matrix (FSM), which states the fault sensitivity of the consistency indicators. Two approaches to sensor placement will be reviewed, which differ on the FSM nature. On the one hand, structural analysis leads to a binary FSM, which can be efficiently handled by the optimisation algorithm applying graph theory tools. On the other hand, the use of an analytical model leads to a more informative non-binary FSM. In both approaches only sub-optimal solutions can be attained. This is due to the fact that in the first approach a structural model is used, which is an abstraction of the analytical model, whereas in the second approach the sensor placement problem must be solved applying clustering techniques. These two approaches will be recalled and compared when applied to a district metered area (DMA) in the Barcelona WDN to decide the best location of pressure sensors for leak monitoring.