Abstract:
Integrated hydrogeological and geophysical methods involving Very Low Frequency
Electromagnetic (VLF-EM), Vertical Electrical Sounding (VES), Multi-criteria Decision Analysis
(MCDA) data mining technique and statistical modeling had been utilized with the aim of
delineating the groundwater potential of Olorunda-Abaa area, Ibadan, Southwestern Nigeria. A
total of five (5) traverses were established across the study area. VLF-EM data were acquired at a
station interval of 10 m along the five traverses while fifty-three (53) VES data were collected in
the study area using Schlumberger array with a total length spread of 100 m – 150 m. The VLFEM
interpretation results delineated conductive zones along the profiles that are typical of
geological structures. The VES result delineated four subsurface geoelectric units consisting of the
topsoil, weathered layer, partly weathered/fractured basement and fresh basement rock. The layer
resistivity values generally ranged from 36 – 584 Ωm, 46 - 488 Ωm, 51 – 263 Ωm and 135 – 1120
Ωm respectively while the thickness values generally varied from 0.6 – 1.2 m, 3.9 – 47.1 m and
6.2 - 49.5 m respectively. The AHP technique was used to integrate all the factors considered
influencing groundwater occurrence for the development of groundwater potential map. The
investigated area was subsequently characterized into high, medium, low and very low potential
zones. The study concluded that the integration of hydrogeological and geophysical data with
Multi-criteria Decision Analysis (MCDA) data mining technique can provide a robust result in
developing a model groundwater potential map for groundwater resources management in the
study area.
