Geoelectrical Characterization of Aquifer Precincts in Parts of Lapai, North Central Nigeria|
TSEPAV, M.T.; IBRAHIM, S.I. & BAYEGUN, F.A.
Some geoelectric characteristics of aquifer in parts of Lapai, Central Nigeria
were evaluated using Wenner vertical electrical sounding (VES) method. Fifteen (15) VES
points were occupied using G41 Geotron Resistivity meter with electrode spacing varying
from 10m to 150m while a global positioning system (GPS) tracking device was used to
locate the VES points. The 1xD Interprex interpretation software was used for the data
interpretation which revealed four layers comprising the top lateritic soil, silty /clayey,
weathered basement and fresh basement rocks. The resistivity of these layers varied from
4.54Ωm to 27987.60Ωm while the depth varied from 0.440m to 1079.5m. Longitudinal
conductance and transverse resistance calculated from the layersf thicknesses and resistivities
varied from 0.00039Siemens to 2.05Siemens and 3.96×106Ωm2 to 3.34×107Ωm2 respectively.
The aquifer overburden protection capacity in VES 2, 5, 6,9,10 and 11 were relatively low
which means the aquifer in these locations are susceptible to contaminants while in VES 15
the protective capacity is higher indicating that the aquifer is protected. Generally, all the
locations could be exploited for groundwater at relatively reasonable depths. However, a
greater part of the study area has low protective capacity (<1.0Siemens). The consequence of
this revelation is that the area is generally unprotected as it allows for infiltration and
subsequent contamination of the groundwater and hence good groundwater quality cannot be
guaranteed in the area.
Conductance; transmissivity; protective capacity; aquifer characterisation