A pressure-based approach for the identification of anomalous events in water distribution networks

In this era of growing population, urbanization and relevant environmental issues, an adequate management of water distribution networks (WDN) is needed to deal with current and future challenges and ensure an efficient water supply. In this context, techniques relying on the use of WDN hydraulic models (i.e., model-based approaches) can be a useful tool to support water utilities in decision-making processes, spacing from leak detection to the definition of maintenance actions. However, model-based approaches generally rely on the availability of a well calibrated hydraulic model of the WDN, which depends on detailed information on WDN features (e.g. topology, pipe characteristics, etc), that may not be available or perfectly known to water utilities.

In the last decades, the process of WDNs digitalization resulted in the availability of a large amount of data (e.g. discharge in pipelines, pressure at nodes, etc.). Among these data, pressure measurements may be particularly easy to obtain, due to the lower costs and limited intrusiveness of pressure sensors compared to flow meters, with the possibility of installing them in a significant number of WDN sections. In light of the above, this study proposes a new method for the identification of anomalous events occurring in a WDN exclusively based on the use of pressure data collected through a series of pressure sensors installed in the network. Even without requiring detailed information on WDN characteristics or the use of the hydraulic model, the method allows detecting both hydraulic anomalies (e.g. anomalous consumption) or mechanical anomalies (e.g. significant leakage events, or unknown gate valves status after maintenance actions) which can significantly impact system functioning and whose prompt identification can improve the quality of the service provided by water utilities.

To effectively detect anomalous events while excluding other potential causes of pressure variations (e.g. changes in the WDN inlet pressure due to modifications in the controls of pumping systems), the method is based on the analysis of pressure differences calculated for all possible couples of sensors located in the WDN, which are expected to deviate from the ordinary range of values only in the case of anomalies because of the local alteration of the pressure-head distribution produced.

The proposed method is tested on a real case study in Northern Italy, featuring around 300 users and provided with a system of pressure sensors collecting data with hourly temporal resolution. The application of the method to the above case study revealed its effectiveness in detecting a series of anomalous events with different magnitude throughout the day. In addition, the method was demonstrated to be capable of identifying anomalies occurring simultaneously in different areas of the WDN. Overall, it is believed that the developed method can provide a solid indication based on which the water utility can promptly act and verify the possible presence of anomalous events of different nature.