Groundwater Prospecting in Coastal Sedimentary Terrain Using 2D ERT and GIS: A Case Study of Ikot Abasi, Nigeria

Abstract

Groundwater demand in Nigeria’s coastal regions is rising, yet subsurface assessment is complicated by heterogeneous sediments and tidal influences. This study applies an integrated approach combining 2D Electrical Resistivity Tomography (ERT), Vertical Electrical Sounding (VES), Geographic Information Systems (GIS), and remote sensing to delineate aquifer zones and assess groundwater quality in Ikot Abasi, Akwa Ibom State. ERT data were collected along three 200 m profiles using a Wenner-Schlumberger array and inverted with Res2Dinv. Twelve VES points provided complementary hydrogeological parameters including transmissivity and hydraulic conductivity. GIS and remote sensing datasets (SRTM DEM, Sentinel-2 imagery, drainage networks, and land cover maps) were used to georeference profiles, analyze terrain influence, and correlate resistivity anomalies with geomorphology. Results revealed three main subsurface units: shallow conductive clayey horizons (<50 Ωm), intermediate silty sands (80-800 Ωm), and deeper resistive aquifer zones (>1000 Ωm) with transmissivity up to 65 m<sup>2</sup>/d. Water quality analyses showed most parameters within WHO standards, although elevated calcium, magnesium, and iron suggest geogenic enrichment from ferruginous sands. The study demonstrates that integrating ERT with GIS and remote sensing improves interpretation of aquifer distribution and groundwater quality in complex deltaic settings. This multidisciplinary workflow provides a more reliable basis for groundwater development and sustainable resource management in Nigeria’s coastal sedimentary terrains.