Geoelectrical Prospecting for Deep Fracture Aquifers in Kadna, part of Minna Sheet164 SW, North Central Nigeria

Abstract

Kadna is an urban sprawl of Minna in North-Central Nigeria. It is populated largely by middle class civil servants that obtain fresh water from six boreholes which produce from shallow fractures. The borcholes are now inadequate to satisfy the water requirements of the spiruling population. Opportunity for increasing the fresh water supply lies in exploiting fractures within depths greater than 60 m. The search for groundwater convergence areas within these deep fractures in Kadna was conducted using surface geological mapping and genelectrical sounding. Rockwork was employed to plot Roselle diagram of measured joint directions, SAS 400M) ABEM terrameter was employed to conduct ID-geoelectrical sounding comprising electrical resistivity, spontaneous potential (SP) and induced polarization (IP) within traverses oriented along foliation strike. The resistivity sounding data was processed and analysed using WinResist inversion software, while the SP and IP were plotted and analysed using Microsoft Excel. The modeled resistivity sounding curves revealed deep fractures of the HKH, HKIK, HIKHKH and KIIKHKH curve types. They are confined fractures characterised by 60-313 Cm resistivity, SP values of -75 to +75 mv, basal elevation of 120 220 m, (with respect to sea level) and IP values of 10- 200 ms. Groundwater convergence area was inferred within the deep fractures in the easternmost part, within longitude E6 596 to E6.610 and latitude N9 561 10 N9.566. This is the choicest area for water borehole drilling, being characterized by 100-200 fm electrical resistivity. - 30 to +50 mv spontaneous potential, basal elevation lower than 180 m, and 10-13.3 m fracture thickness. The second ranking choice arca for drilling lies within longitude" 1.5945" to E6.5965 and latitude N9.561" to N9.566" The third ranking choice area for drilling lies within longitude E6.5945° to E6.5965 and latitude N9.561° to N9.566.