Diagnosis of Water Distribution Systems through Transient Tests: The Pilot Study of Milan

This paper presents the results of a pilot study funded by Metropolitana Milanese to investigate the use of transient tests for the diagnosis of the water distribution network of Milan (Italy). The peculiar aspects of the application of transient-based techniques to a complex system in an urban environment are discussed. Synchronous pressure signals acquired at 2,048 and 1,000 Hz at different measurement sections are shown and analyzed by auto-and cross-correlation, and wavelet transform. The effects of the shape of the pressure wave introduced in the system by the manoeuvre of a valve and the effects of repetition of the same manoeuvre on the reliability of the results are discussed. The main practical lessons learned about the use of hydrants, the topological and effective distances of measurement sections, the need for the introduction of pressure waves of given shapes, the information carried by the pressure signals for the diagnosis, and the use of simplified wavelet analysis are also presented and discussed.