Leakage detection and localization of large diam water pipeline based on multi-source geophysical data analysis

Pipeline leakage in subterranean water supply systems threatens structural integrity and public safety. Locating leaks in medium and large-diameter pipelines is challenging due to their underground concealment. This paper presents a series of geophysical tests on main water supply pipelines, exploring suitable leakage detection methods, including Frequency Electromagnetic Method (FEM), Ground Penetrating Radar (GPR), and Electrical Resistivity Tomography (ERT). The accuracy, range, and efficiency of these methods were compared, and a composite verification was performed to propose an integrated detection approach. Two suspected leakage sections were selected for comprehensive testing, with multi-source geophysical data collected. Results show that the FEM can effectively detect and locate the approximate orientation of anomalies. The GPR method precisely identifies pipeline location, depth, and voids or water-rich areas. ERT provides a finer distribution of anomalies, corroborating FEM and GPR findings. Finally, the detection results were verified by drilling sampling. Based on these findings, a pipeline leakage risk coefficient K was defined to classify and evaluate rapid detection anomalies. The calculations confirm that both resurvey areas fall within the high-risk leakage range, demonstrating the method's high accuracy. This integrated approach provides an effective, reliable method for detecting leaks in large-diam pipelines.