Groundwater Exploration of Federal College of Education (Technical) Akoka Lagos Nigeria Community Using Schlumberger Array

Abstract

A total of thirteen (13) Vertical Electrical Soundings (VES) using Schlumberger array were carried out within Federal College of Education (Tech) Akoka, Yaba, Lagos State, Southwestern, Nigeria. This area is between Longitude N06º31’10” and Longitude N06º31’30” and Latitude E3º22′ 55″ and Latitude E3º23′ 5.3″. This study was necessary because of the roles water plays in human life, the demand for it and the failure of boreholes in some locations within the study area. Resistivity method of geophysical survey was applied to determine good locations for groundwater prospecting using PASI Terrameter and its accessories. The resistivity values obtained were plotted on a log-log graph scale for curve matching and computer iteration was carried out using WinResist software to generate computer models for the curve types. The Geoelectric sections beneath each VES point revealed about four to five geoelectric layers, comprising topsoil, sandy-clay, clayey-sand, clay, peat, and sandy formation. Analysis of geophysical investigation showed that sand at the third geoelectric layer in VES 1 and VES 11 with a resistivity value of 143.3 Ωm and 240 Ωm constitute aquifer units where groundwater can be tapped. The shallow groundwater could be tapped at depth interval 6.6-20.2 m in VES 1 and 25.2m and above in VES 11. The failure of borehole located within the female hostel was due to overburden of this shallow aquifer due to population explosion. The recommendation was made that groundwater development through borehole drilling of depth not less than 150m is needed for high groundwater yield based on available information from nearby well log since wider spread for the deep investigation is not possible within the study area.