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<p>This study investigates groundwater–surface water interactions in Akwa Ibom State, Southern Nigeria, with emphasis on aquifer systems adjacent to the main river channel and its tributaries. Understanding these interactions is critical for effective water resource management, particularly in regions dependent on groundwater for drinking water supply. Exchanges between groundwater and surface water influence hydrologic fluxes, nutrient transport, and pollutant migration, with implications for water quality, ecosystem health, and aquifer sustainability. Geoelectric methods were employed with the aim to characterize aquifer properties and evaluate their hydrodynamic behavior. Resistivity measurements provided formation factors, from which porosity, tortuosity, hydraulic conductivity, and permeability were derived. Transmissivity values were determined from aquifer thickness and hydraulic conductivity, enabling classification of aquifer zones based on water supply potential. Recharge and discharge zones were delineated, with resistivity ratios indicating approximately 56% recharge and 44% discharge. Aquifer resistivity ranged from 7.7 to 2408.7 Ωm (average 550.7 Ωm), while water resistivity values (0.44–152.81 Ωm) suggesting possible seawater intrusion in coastal zones. Porosity varied from 0.104 to 0.54, tortuosity from 0.9 to 1.3, and hydraulic conductivity exhibited wide spatial variation, reflecting lithological heterogeneity. Transmissivity ranged between 18.72 and 1988.27&#xa0;m²/day, highlighting zones with differing groundwater potential. To address uncertainty and prioritize influencing parameters, a Pareto analysis combined with the Analytic Hierarchy Process (AHP) was applied. Seven factors, permeability, hydraulic conductivity, transmissivity, proximity to water channel, aquifer thickness, topography, and porosity, were evaluated using a Pairwise Comparison Matrix (PCM). Weight calculations revealed that permeability, hydraulic conductivity, and transmissivity carried the highest significance due to their direct role in water flow, recharge, and contaminant spread. Proximity to water channel and aquifer thickness had moderate influence, while topography and porosity ranked lower. Consistency testing (CI and CR &lt; 0.1) validated the reliability of the weighting. The resulting Pareto chart emphasized the “vital few” hydrogeological factors requiring targeted management. In general, the findings underscore the mechanistic value of electrical prospecting for understanding aquifer behavior adjacent to river channels. By integrating geoelectric analysis with Pareto–AHP prioritization, this study provides a decision-support framework for sustainable groundwater management in coastal aquifer systems vulnerable to seawater intrusion.</p>

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Mechanistic understanding of electrical prospecting for aquifer systems adjacent to main river channels and their tributaries in Akwa Ibom, Southern Nigeria: hydrogeological implications

  • 期刊论文

  • 发表日期：

    2025年9月8日

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  • K. R. Ekanem,
  • N. J. George,
  • A. M. Ekanem,
  • N. I. Udosen,
  • J. E. Thomas

摘要

This study investigates groundwater–surface water interactions in Akwa Ibom State, Southern Nigeria, with emphasis on aquifer systems adjacent to the main river channel and its tributaries. Understanding these interactions is critical for effective water resource management, particularly in regions dependent on groundwater for drinking water supply. Exchanges between groundwater and surface water influence hydrologic fluxes, nutrient transport, and pollutant migration, with implications for water quality, ecosystem health, and aquifer sustainability. Geoelectric methods were employed with the aim to characterize aquifer properties and evaluate their hydrodynamic behavior. Resistivity measurements provided formation factors, from which porosity, tortuosity, hydraulic conductivity, and permeability were derived. Transmissivity values were determined from aquifer thickness and hydraulic conductivity, enabling classification of aquifer zones based on water supply potential. Recharge and discharge zones were delineated, with resistivity ratios indicating approximately 56% recharge and 44% discharge. Aquifer resistivity ranged from 7.7 to 2408.7 Ωm (average 550.7 Ωm), while water resistivity values (0.44–152.81 Ωm) suggesting possible seawater intrusion in coastal zones. Porosity varied from 0.104 to 0.54, tortuosity from 0.9 to 1.3, and hydraulic conductivity exhibited wide spatial variation, reflecting lithological heterogeneity. Transmissivity ranged between 18.72 and 1988.27 m²/day, highlighting zones with differing groundwater potential. To address uncertainty and prioritize influencing parameters, a Pareto analysis combined with the Analytic Hierarchy Process (AHP) was applied. Seven factors, permeability, hydraulic conductivity, transmissivity, proximity to water channel, aquifer thickness, topography, and porosity, were evaluated using a Pairwise Comparison Matrix (PCM). Weight calculations revealed that permeability, hydraulic conductivity, and transmissivity carried the highest significance due to their direct role in water flow, recharge, and contaminant spread. Proximity to water channel and aquifer thickness had moderate influence, while topography and porosity ranked lower. Consistency testing (CI and CR < 0.1) validated the reliability of the weighting. The resulting Pareto chart emphasized the “vital few” hydrogeological factors requiring targeted management. In general, the findings underscore the mechanistic value of electrical prospecting for understanding aquifer behavior adjacent to river channels. By integrating geoelectric analysis with Pareto–AHP prioritization, this study provides a decision-support framework for sustainable groundwater management in coastal aquifer systems vulnerable to seawater intrusion.