Basement Groundwater Potentials Evaluation Using Resistivity Method: Ogugu and Environs, Akoko-Edo, Southwestern Nigeria as A Case Study

Year 2024, Volume: 6 Issue: 1, 29 - 36, 15.05.2024

Adeoye Sikiru Salami Emmanuel Muyiwa Babafemi Omasan Godwin Akperi

Abstract

Groundwater development within the Basement Complex terrain relies on the existence of discrete secondary porosity of the basement rock mass in the subsurface. A total of twelve geoelectric sounding locations were occupied at and around Ogugu to evaluate the groundwater potentials of Ogugu and adjoining areas. Field data were acquired using Schlumberger array. The data were interpreted using RES1D and Interpex software for model convergence consistency tests. The results of the interpretation yielded a five to six electrostratification of the subsurface within the depth resolution of the attained maximum spread. The geoelectric layers were resolved into four to five geologic layering at the Vertical Electrical Sounding (VES) locations. The topmost layer represents the topsoil which is underlain by wet lateritic layer. Below this is the clayey layer followed by the fractured basement and fresh basement layers. Several hydrogeologically significant maps: Fractured zone thickness (FZT) map, Overburden thickness (OBT) map, Clay thickness (CT) map and Isoresistivity (IR) map were generated. Hydro-resistivity parameters such as Total Transverse Resistance (TTR), Total Longitudinal Conductance (TLC), Resistivity Reflection Co-efficient (RRC) and Resistivity Contrast (RC) were computed and used together with the generated maps to evaluate the groundwater potentials of the Ogugu community and environs through the prospectivity ranking of the VES locations for optimal boreholes siting. The ranking shows the topmost five locations to be VES3, VES5, VES6, VES7 and VES10.

Keywords

Groundwater, Basement Complex, Ogugu, Schlumberger, Hydro-resistivity

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