Geoelectrical and Geological Characterization of Groundwater Availability in Nnamdi Azikiwe University Awka and Its Environs, South Eastern Nigeria.

A geoelectrical and geological survey of Nnamdi Azikiwe University Awka (UNIZIK) and its environs was carried out to determine the groundwater availability in the region. The area was bounded by latitude 60 00’N, 6015’N and longitude 7000’E, 7009’E having an approximate area expanse of about 18.62km. The survey aimed to evaluate the geological parameters that will influence groundwater potential through resistivity variation characteristics of the subsurface. The geological study reveals that the area is underlain by Imo Shale and as such the wells have low water supply due to seasonal availability and other challenges related to the subsurface geological conditions primarily marked by the prevalence of shale formations. The resistivity imaging measurement used employed Schlumberger electrode configuration using the Alpha-T Resistivity Meter. A total number of nine (9) vertical electrical soundings (VES) points were established. The interpretation of the VES data revealed 4 to 5 geoelectric units, comprising topsoil, clayey sand, sandstone, dry sand, water-saturated sandstone and shale. The water-saturated sandstone formed the aquiferous unit. The apparent resistivity of the aquiferous unit ranged from 8.13Ωm to 296Ωm, the thickness ranged from 40m to 109.2m and the depth to the aquifer ranged from 120m to 200m. Aquifer characteristics in the form of transmissivity and hydraulic conductivity calculated from interpreted VES results varied from 0.4682m2/day to 620.728 m2/day and 0.003378m/day to 0.03878m/day, which inferred high to extremely high transmissivity and moderate to high hydraulic conductivity respectively.