Framework for Developing Resistivity Models to Identify Potential Safety Threats in Embankment Dams and Assessing the use of Bentonite in Repairing Deep Cracks in the Embankments

The structural integrity of embankments is critical for sustainable water resource management, particularly in seismic-prone regions. This study presents a comprehensive framework integrating field inspections, geophysical assessments, and geotechnical interventions to identify and rehabilitate subsurface anomalies in earthfill embankment dams. The Mangla Dam in Pakistan was selected to demonstrate the framework’s practicality. Following the 24 September 2019 earthquake, Sukian Dyke, a major embankment section, was severely damaged with transverse and longitudinal cracks. To address this, a four-phase methodology was developed. First, physical inspections and Ground Penetrating Radar (GPR) surveys determined the extent and geometry of cracks. Second, a bentonite mixture was formulated and used to seal cavities. Third, a post-repair GPR survey confirmed the efficacy of sealing. Finally, an Electrical Resistivity Tomography (ERT) survey evaluated the hydraulic performance of treated zones. Results showed higher electrical resistivity (100–150 Ω·m) in repaired areas, confirming the bentonite’s effectiveness. This research represents Pakistan’s first integrated geophysical–geotechnical investigation of earthfill dams, setting a precedent for safety monitoring and resilience enhancement in seismic regions.