[01] Ibeneme Sabinus Ikechukwu, Department of Geology, School of Physical Sciences, Federal University of Technology, Owerri, Nigeria. [02] Ibe Kalu Kalu, Department of Geology, School of Physical Sciences, Federal University of Technology, Owerri, Nigeria. [03] Thompson Takon Peter, Department of Geology, School of Physical Sciences, Federal University of Technology, Owerri, Nigeria. [04] Onyekuru Samuel Okechukwu, Department of Geology, School of Physical Sciences, Federal University of Technology, Owerri, Nigeria. [05] Ihejirika Chinedu, Department of Environmental Management, School of Environmental Sciences, Federal University of Technology, Owerri, Nigeria.

Aquifer mapping and assessment of groundwater vulnerability to pollution within Isuikwuato and environs were carried out. Forty nine Vertical Electrical Sounding (VES) data were acquired with eight parametrically sounded. Grain size analysis of aquifer materials from eight boreholes was carried out. The DRASTIC method was integrated with GIS to develop the vulnerability index map for the groundwater system in the area. Depth to water table, aquifer thickness, Hydraulic Conductivity, Transmissivity, Storativity, Diffusivity and Transverse Resistance were observed to be low within Acha and southwest of Nunya. These parameters were high around Eluama, Otampa, Umuasua, Amiyi, Uturu and Ahaba which made these localities to have high prospects for groundwater development than Acha and Nunya areas. Aquifer vulnerability to pollution within Isuikwuato and environs ranges from “Minimum” with an index less than 79 in south of Nunya to “Moderately Low” with index ranging from 120-139 in Eluama, Umuasua and Otampa regions. Uturu, Amiyi, Ovim and Ahaba are rated as “Low” with index ranging from 100-119. The generally low vulnerability levels of the study area are attributed to high depth to the piezometric surface and the steep topography which affects the degree of percolation. Areas with moderately low vulnerability such as Eluama and Otampa possibly results from the massive sandstone layers with high Hydraulic Conductivities and Transmissivities as well as low Longitudinal Conductance which is in the order of 0.00155Ω-1 m. This research has generated baseline information for future aquifer monitoring in the area.

Aquifer, Diffusivity, DRASTIC, Storativity, Transmissivity, Vulnerability

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