Hydrogeophysical assessment and protective capacity of groundwater resources in parts of Ezza and Ikwo areas, southeastern Nigeria

Geoelectrical investigations were carried to determine the aquifer potentials and protective capacity of Ezza and Ikwo areas, Ebonyi State, Southeastern Nigeria. A total of thirty-five (35) Vertical Electrical Sounding survey was conducted using the Schlumberger configuration to evaluate the character of the aquifers in the studied locations. Geoelectric sections derived from the modeling of the sounding data reveal 4 to 7 subsurface layers. The Vertical Electrical Sounding curves obtained were QH, QHK, QHKH, QQH, KHK, QHAK, and QQHK. The third and fourth layers constitute the aquiferous zones. The aquifer resistivity ranges from 11.7 to 814 Ωm, while the aquifer thickness and depth range from 99.2 to 3.4 m and 8.7 to 105.8 m respectively. The Dar Zarrouk (longitudinal conductance and transverse resistance) parameters were determined from the results. The longitudinal conductivity ranges from 0.004975 to 2.9573 mhos, whereas the transverse resistance ranges from 70.1 to 17,161.6 Ωm2. Furthermore, the aquifer potentials of the study area were shown to differ with aquifer size, structure and characteristics are influenced by the underlying geology generally. From the study, it was concluded that the western axis of the study area underlying the Ebonyi Formation has a higher aquifer potential compared to the eastern axis underlying the Abakaliki Formation. This is supported by the geology of the area with the Abakaliki Formation dominated by shales that have very low permeability, while the Ebonyi Formation consists of shales with alternations of sandstone which supports good aquifer conditions. The study area has a moderate aquifer protective capacity.