GEOPHYSICAL SITE INVESTIGATION OF THE FEDERAL COLLEGE OF EDUCATION, ZARIA, NIGERIA
GEOPHYSICAL SITE INVESTIGATION OF THE FEDERAL COLLEGE OF EDUCATION, ZARIA, NIGERIA
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Date
1999-08
Authors
OLATUNJI, SAMINU
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Abstract
A comprehensive geophysical survey was carried out over the premises of the
Federal College of Education, Zaria, with a view to investigating the depth to basement,
depth to and thickness of aquifer, depth to and thickness of the weathered basement as well
as the subsurface structural systems such as the fractures and faults. The D.C. Resistivity
and VLF methods were employed to accomplish the study. The conventional vertical
Electrical Sounding (VES) using Schlumberger array was carried out at 40 stations, 8 of
which were Radial stations with 4 profiles per station. So a total of 64 profiles were
sounded. VLF data were taken from all the VES stations as well. ABM Terrameter (SAS
300P) was used to collect resistivity data while EM/6 VLF equipment was used to collect
the VLF data. Results from the interpretation of the data collected suggest 3 layers in most
parts of the area studied. However, there are cases of 2 layers. The resistivity value for the
first layer (topsoil) varies from 30 to 300 ohm-meters with thickness ranging between 3.5
and 14 m. The second layer (weathered basement) has resistivity values of 84 to 480 ohmmeters
and thickness of between 9 and 36.5 meters. Its depth varies from 5 to 14 meters.
The third layer appeared to be the bedrock with the resistivity value as much as 3000 ohmmeters
in some locations. Towards the eastern part of the study area, the fresh bedrock
records the greatest depth of about 40.1 m. The depth of aquifer ranges from 1.5 to 4.0
meters while its thickness ranges from 5 to 14 m. Further, the geologic sections derived in
this work together with the aquifer plots suggest that weathered basement in the area does
not entirely represent a promising aquifer for the fact that in some cases, aquifers occurred
both in the topsoil and in the weathered basement while it disappeared in some areas of
weathered basement. Radial sounding plots revealed the existence of anisotropics, trending
NE-SW, NVV-SE and E - W directions. The VLF interpretations similarly indicated the presence of vertical contact or fractures zones which is more pronounced towards the
western part of the survey area. The highest conductivity in the area occurs towards the
west as can be seen from VLF plots. There is hence a strong water-bearing potential within
the subsurface rocks in this part of the study area.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE
SCHOOL, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT, OF THE
REQUIREMENTS FOR THE AWARD OF THE
DEGREE OF MASTER OF SCIENCE IN APPLIED
GEOPHYSICS
DEPARTMENT OF PHYSICS
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY
ZARIA
Keywords
GEOPHYSICAL,, FEDERAL COLLEGE OF EDUCATION, ZARIA, NIGERIA