Integrated VES, ERT, and SP Approach for Local-Scale Aquifer Characterization in a Structurally Complex Basin

Abstract

Groundwater resources have gained strategic importance due to increasing population pressure, climate change, and limited surface water availability. In structurally complex hydrogeological settings, local-scale aquifer characterization requires integrated geophysical approaches. This study employs Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT), and Self Potential (SP) methods to characterize subsurface structure and delineate aquifer systems in a tectonically complex basin. The subsurface geology is highly heterogeneous, consisting of contrasting lithological units where tectonic contacts control groundwater occurrence. While massive ophiolitic units generally act as low-permeability barriers, secondary porosity developed through fracturing provides localized groundwater pathways. VES data from seven stations provided information on vertical resistivity variations and subsurface layering, while two 500 m-long ERT profiles revealed lateral resistivity heterogeneities and potential aquifer zones. SP measurements along four profiles identified groundwater-related anomalies and structurally controlled flow paths, with negative anomalies reaching -24 mV. The integrated geophysical interpretation was supported by borehole data, enhancing the reliability of subsurface characterization. Borehole BH-1 encountered low permeability conditions within massive serpentinites, whereas BH-2 intersected fractured ophiolitic units and carbonate basement, indicating significantly higher hydraulic conductivity. These results confirm that fracture-controlled permeability is the dominant factor governing local aquifer development. The study demonstrates that the integrated application of VES, ERT, and SP methods provides a robust framework for local-scale aquifer characterization in structurally complex environments.