Integrated geophysical survey of an earthen dam using electrical resistivity tomography and UAV-derived topographic data

This study aims to improve the detection of internal seepage zones in earthen dams by integrating Electrical Resistivity Tomography (ERT), UAV-derived topographic data, and GIS technology. Monitoring the internal condition of hydraulic structures is essential to identify potential failure risks before they become critical. The methodology involved acquiring ERT profiles along multiple profiles along a dam, with electrode elevations first measured using GPS and then corrected using high-resolution digital elevation models (DEMs) generated from UAV surveys. These datasets were processed and analyzed within a GIS environment to assess the impact of elevation accuracy on subsurface modeling. The findings revealed that the inclusion of UAV-based DEMs improved the vertical resolution of geoelectrical models, reducing depth estimation errors and allowing for more precise delineation of subsurface anomalies. Four low resistance zones (<20 Ω·m) were detected at depths of 15–25 meters, spatially aligned with visible signs of seepage and erosion. The results demonstrate that combining geophysical surveys with remote sensing based on UAVs enhances the reliability of dam condition assessments. This integrated, non-invasive approach provides a cost-effective and scalable solution for routine dam safety monitoring and retrospective analysis, offering practical value for infrastructure managers, engineers, and regulatory agencies.