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<p>One of the pressing global challenges is ensuring the availability of freshwater that is both sufficient and sustainable. Operative management and utilization of groundwater entail an exhaustive understanding of aquifer characteristics within their specific geological and environmental contexts. This study presents an integrated geophysical and hydrogeological evaluation of groundwater systems in and around Obio Akpa Campus of Akwa Ibom State University (AKSU), Nigeria. Unlike earlier studies in the Niger Delta, southern Nigeria that applied GOD and Archie’s law in broad regional contexts, this study adapts these methods to a micro-hydrogeological setting characterized by drainage failures, land-use pressure, and proximity to water channels. Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) were applied at 8 and 30 locations, respectively, and complemented with borehole logs to provide a multi-scale dataset integration uncommon in prior regional studies. Results show that the subsurface comprises three to four poorly sorted sand layers with occasional clay embolisms. The aquifer unit is highly heterogeneous, with thicknesses ranging from 12.5 to 94.3&#xa0;m and depths between 0.9 and 44.1&#xa0;m. The southwestern portion of the investigation site exhibits high permeability and favourable groundwater flow conditions. Based on transmissivity values, groundwater potential is categorized as moderate (3.3%) and high (96.7%), corroborated by an estimated groundwater reserve of 7.15 × 10⁸ ± 2.87 × 10⁷ m³. Furthermore, resistivity-derived porosity and hydraulic conductivity were normalized against WHO/SON water quality standards, providing a direct link between aquifer properties and groundwater safety indices. Protection against contaminant infiltration varies considerably, with longitudinal conductance values indicating poor (76.7%), weak (13.3%), moderate (6.7%), and good (3.3%) protective capacities. The GOD-index assessment of groundwater contamination risk reveals 5 susceptibility categories: very low (16.7%), low (10.0%), moderate (3.3%), high (60.0%), and very high (10.0%). While the aquifer systems are prolific, their high susceptibility to contamination highlights significant risks. These study findings underscore the necessity of targeted groundwater preservation strategies, while the contextual adaptation, dataset integration, and quantitative normalization framework presented here contribute a novel approach to aquifer vulnerability assessment in southern Nigeria.</p>

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Combined geophysical and hydrogeological evaluation of groundwater characteristics in and around Obio Akpa Campus, Akwa Ibom State University, Nigeria

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  • 发表日期：

    2025年10月29日

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  • Aniekan M. Ekanem,
  • Samuel T. Ebong

摘要

One of the pressing global challenges is ensuring the availability of freshwater that is both sufficient and sustainable. Operative management and utilization of groundwater entail an exhaustive understanding of aquifer characteristics within their specific geological and environmental contexts. This study presents an integrated geophysical and hydrogeological evaluation of groundwater systems in and around Obio Akpa Campus of Akwa Ibom State University (AKSU), Nigeria. Unlike earlier studies in the Niger Delta, southern Nigeria that applied GOD and Archie’s law in broad regional contexts, this study adapts these methods to a micro-hydrogeological setting characterized by drainage failures, land-use pressure, and proximity to water channels. Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) were applied at 8 and 30 locations, respectively, and complemented with borehole logs to provide a multi-scale dataset integration uncommon in prior regional studies. Results show that the subsurface comprises three to four poorly sorted sand layers with occasional clay embolisms. The aquifer unit is highly heterogeneous, with thicknesses ranging from 12.5 to 94.3 m and depths between 0.9 and 44.1 m. The southwestern portion of the investigation site exhibits high permeability and favourable groundwater flow conditions. Based on transmissivity values, groundwater potential is categorized as moderate (3.3%) and high (96.7%), corroborated by an estimated groundwater reserve of 7.15 × 10⁸ ± 2.87 × 10⁷ m³. Furthermore, resistivity-derived porosity and hydraulic conductivity were normalized against WHO/SON water quality standards, providing a direct link between aquifer properties and groundwater safety indices. Protection against contaminant infiltration varies considerably, with longitudinal conductance values indicating poor (76.7%), weak (13.3%), moderate (6.7%), and good (3.3%) protective capacities. The GOD-index assessment of groundwater contamination risk reveals 5 susceptibility categories: very low (16.7%), low (10.0%), moderate (3.3%), high (60.0%), and very high (10.0%). While the aquifer systems are prolific, their high susceptibility to contamination highlights significant risks. These study findings underscore the necessity of targeted groundwater preservation strategies, while the contextual adaptation, dataset integration, and quantitative normalization framework presented here contribute a novel approach to aquifer vulnerability assessment in southern Nigeria.