Transient-based Characterization for Different Pipe Defects in Urban Water Supply Systems

Different types of pipe defects commonly exist in water supply systems. These potential defects may result in severe problems of system operation and function as well as huge waste of water and energy resources. Current detection methods for these pipe defects are inadequate for their accuracy and/or efficiency, which can be evidenced by the existing serious situation of water and energy losses (over 30%) in the water supply systems in the world. Recently, an innovative method, termed as transient-based method (TBM) that relies on the transient pressure wave, has been developed and applied for the diagnosis of different pipe defects. Although it is efficient, non-intrusive and economic, this TBM is so far applicable only to relarively simple or idealized defect situations, for example, single pipeline with a pre-known type of pipe defects. In practical systems, however, different types of defects may occur simultaneously in the pipeline system, which is hardly identified by current TBMs. To this end, an extension of the innovative TBM for characterizing and identifying different types of pipe defects is of great practical significance, which is the scope of this study. Three common types of pipe defects – leakage, discrete and extended blockages – are examined in this study. The system frequency response (SFR) based method is taken for this investigation for its convenience of analytical derivation and tolerance of system noises as observed in the literature. With this study, different SFR expressions are firstly to be derived for charactering the types of different pipe defects, and then the TBM will be used for identifying each type of defects (number, size and location, etc.). The developed method will be validated through numerical and experimental tests. The results are analyzed and discussed for both aspects of advantages and limitations of the TBM, so as to obtain useful implications to the practical use of this method. The achievement of this study may provide substantial progress on the development and application of TBM.