A regional geoelectric investigation for groundwater exploration in Minna area, north west Nigeria.

Abstract

A Regional Geoelectric survey using the Vertical Electrical Resistivity (VES) was used to investigate the land mass covering Minna and it's environ in Nigeria aimed at assessing the lithology beneath the area, delineate the aquiferous formations and its depths and thicknesses. The area was grided into 13 profiles spaced at 3 km intervals with each having 13 stations for the VES. A total of 169 VES points were occupied. The Global Positioning System (GPS) equipment was used for locating the stations on ground. The interpretation of the field data was carried out using the Zhody soft-ware, which converts the apparent resistivity as a function of electrode spacing to the true resistivity as a function of depth in two dimensions. The rocks of the area are largely of crystalline rocks, which include gneisses, migmatites and metasedimentary schists. The results show that the area is underlain by three layer lithologic sections. In some sections where the basement had probably suffered severe weathering and or fracturing, four or five layer models were obtained. The weathered/fractured layers along the transitional zones form the aquiferous formations in the area with a maximum thickness of about 45m.