Integrated DC resistivity and seismic refraction imaging for bedrock discontinuity mapping in New Minia city, Egypt

This study addresses geotechnical challenges in fractured limestone environments by integrating electrical resistivity tomography (ERT), seismic refraction, and direct current (DC) resistivity soundings with borehole data in New Minia city, Upper Egypt. The objective was to delineate shallow subsurface heterogeneity and structural discontinuities and to establish correlations between geophysical and geotechnical parameters. A genetic algorithm (GA) optimization was applied to DC resistivity inversion, reducing non-uniqueness and improving model convergence. Seventeen boreholes (10 m depth) provided constraints for calibration and validation. Results reveal three principal subsurface sequences: (1) sandy-silty soil with clay intercalations, (2) heterogeneous intermediate deposits, and (3) fractured limestone bedrock. Major structural features, including north-south trending faults, were clearly identified. The integrated approach enhances subsurface characterization, reduces interpretational uncertainty, and provides a robust framework for hazard assessment and urban planning in complex carbonate terrains.