Investigation of aquifer vulnerability to pollution using index Based-Models within Okigwe South, Imo State, Nigeria

Published
2026-06-23
DOI: https://doi.org/10.14295/ras.v40i2.30395
Keywords: Vulnerabilidade de aquíferos, Poluição de águas subterrânea, Modelos baseados em índices, Proteção de águas subterrâneas Aquifer Vulnerability, Groundwater Pollution, Index-Based Models, Groundwater Protection

    Authors

  • Jude Maduabuchi Anyanwu University of Nigeria – Nigeria
  • Daniel Nnaemeka Obiora University of Nigeria – Nigeria
  • Desmond Okechukwu Ugbor University of Nigeria – Nigeria
  • Johnson Cletus Ibuot University of Nigeria – Nigeria
  • James Obinna Sampson University of Nigeria – Nigeria

Abstract

Groundwater is the primary source of potable water in Okigwe South, southeastern Nigeria, yet increasing anthropogenic activities pose significant contamination risks to the underlying aquifers. This study integrated geophysical, hydrogeological, and hydrochemical approaches to assess aquifer vulnerability and groundwater quality in the area. A total of 50 Vertical Electrical Sounding (VES) surveys using the Schlumberger configuration and 8 groundwater samples were collected across Ehime-Mbano, Ihitte/Uboma, and Obowo Local Government Areas. Aquifer vulnerability was evaluated using the Aquifer Vulnerability Index (AVI), DRASTIC, and SINTACS models, while groundwater quality was assessed using the Water Quality Index (WQI). Geo-electrical parameters derived from VES data were used to characterize subsurface lithology and estimate hydraulic properties of protective layers. Spatial analysis and contour map generation were carried out using Python-based scripts for interpolation and visualization. The results indicate moderate to very high aquifer vulnerability, particularly within Obowo LGA, largely controlled by shallow water table conditions, permeable sandy lithologies, and thin vadose zones. WQI results reveal groundwater quality ranging from good to very poor, with zones of degraded quality correlating well with areas of high vulnerability identified by the index-based models. The integration of geophysical and hydrochemical data enhances confidence in vulnerability assessment and provides a robust framework for groundwater protection planning. The generated vulnerability and water quality maps offer valuable tools for sustainable groundwater management and regulatory decision-making in Okigwe South.

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How to Cite
Anyanwu, J. M., Obiora, D. N., Ugbor, D. O., Ibuot, J. C., & Sampson, J. O. (2026). Investigation of aquifer vulnerability to pollution using index Based-Models within Okigwe South, Imo State, Nigeria . Águas Subterrâneas, 40(2), 1–19. https://doi.org/10.14295/ras.v40i2.30395