Mapping water pipeline leakage by ground-penetrating radar diffraction imaging

Investigation of water pipeline leakage is a matter of great significance for water resources management. Among various approaches, ground-penetrating radar (GPR) attracts increasing attention as a fast and noninvasive technique. However, this method suffers from uncertainties in the stage of interpretation because diffractions from the leak region often are too weak to be identified. To address this problem, we have developed the use of diffraction imaging to enhance imaging and characterization of water leakage. Numerical seepage simulation allows us to establish an equivalent computational analog for a known leak condition. After the collection of parallel GPR survey lines, we apply diffraction separation and imaging techniques on 2D and 3D data. Although the actual situation is generally well reproduced by 2D and 3D results, 3D diffraction imaging provides improved mapping of leakage compared with its 2D counterpart. We then apply the method to field data collected at a training base for water pipeline leakage control in Shaoxing, China. The prediction from imaging results corresponds well with the true position and type of leakage. The laboratory and field experiments substantiate the viability of GPR diffraction imaging and illustrate the potential of using GPR to detect small water leaks.