The Use of Electrical Resistivity Tomography for the Characterisation of Voids in a Canal Embankment, Yorkshire, UK

As part of an ongoing investigation into a leakage problem on the Aire and Calder Navigation in Yorkshire, UK, a geophysical study was undertaken in order to characterise voiding observed on a canal embankment near Whitley Bridge, Eggborough. Among other techniques, electrical resistivity tomography (ERT) surveys were carried out. 3D ERT over a known void using resistance data acquired at 0.5 m electrode spacing produced excellent results; key features such as the resistive void space, conductive base flow, and conductive zone of enhanced saturation below the void were imaged successfully within a local 3D resistivity model. Continuous 2D ERT along the embankment using a 2.5 m electrode spacing produced useful results, leading to the identification of potentially problematic locations along the walled section of canal. In conclusion, it appears that geophysical investigation of canal embankments of the type encountered at Eggborough is entirely appropriate and can produce information that would otherwise be impossible to obtain. We were encouraged by the ability of ERT to characterise and delineate existing voids and zones of increased saturation within an embankment and identify possible problematic areas.