The Use of Combined Geophysical Survey Methods for Groundwater Investigation in a Typical Basement Complex Terrain: Case Study of Erunmu, Ibadan, Southwest Nigeria

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Abudulawal, Lukuman


A combined Survey involving the very low frequency electromagnetic (VLF – EM) and Electrical resistivity surveys were carried out in order to appraise the groundwater potential, and locate appropriate positions for sighting boreholes in Erunmu Community, Egbeda local government area, Oyo State, Nigeria. VLF data were obtained along five traverses as the first step in order to locate suitable vertical electrical sounding (VES) stations. Vertical Electrical Soundings using Schlumberger array were thereafter carried out at twenty 20) locations. The integrated interpretation of both data confirms the presence of aquifers, which includes, weathered zone and basement transition/fractures beneath the area, which prior to this investigation have a history of failed boreholes and wells. The resistivity curve types obtained includes H and A which revealed the presence of 3 to 4 subsurface layers consisting of topsoil, the clay, the sandy clay, fractured zone and the highly resistive bedrock. The resulting geo-electric section from the interpretation revealed the Reflection coefficient which ranges from 0.45 – 0.98. The dominated curve type in the area investigated is the H which is typical of basement complex while the A-type is about 20% of the total curves. Hydrogeological, the topsoil is not important because the degree of water saturation in this layer is very low and cannot be utilized for groundwater. The fractured basement layer (which is present in less than 15% of the study area is very relevant in groundwater prospecting; when it is thick enough the layer could support borehole drilling. Areas identified as geological interfaces in the VLF anomaly charts were also confirmed by the interpreted VES data as poor and intermediate zones for groundwater potential in the study area. The significance of this study is such that it will serve as a useful reference for future research efforts in the aspect of basement complex groundwater studies.

Vertical electrical sounding (VES), VLF-EM, reflection coefficient, basement layer

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How to Cite
Lukuman, A. (2019). The Use of Combined Geophysical Survey Methods for Groundwater Investigation in a Typical Basement Complex Terrain: Case Study of Erunmu, Ibadan, Southwest Nigeria. Journal of Geography, Environment and Earth Science International, 23(2), 1-16.
Original Research Article


Ariyo SO, Adeyemi GO, Oyebamiji AO. Electromagnetic VLF survey for groundwater development in a contact terrain: A case study of Ishara-Remo, Southwestern Nigeria. Journal of Applied Science Research. 2009;5(9):1239-1246.

Olayinka AI, Amidu SA, Oladunjoye MA. Use of electromagnetic profiling and sounding for groundwater exploration in the crystalline basement area of Igbeti, Southwestern Nigeria. Global Journal of Geological Science. 2004;2(2):243-253.

Kelly EW. Geoelectric sounding for delineating ground water contamination. Ground Water. 1976;14:6-11.

Koefoed O. Resistivity sounding on an Earth model containing Transition Layers with Linear change of Resistivity with Depth Geophysical Prospecting. 1979b;27: 862-868.

Urish DW. The practical application of surface electrical resistivity to detection of groundwater pollution: Ground Water. 1983;21:144–152.

Mazac O, Kelly WE, Landa I. Surface geo-electrics for groundwater pollution and protection studies. J. Hydro. 1987;93:277-294.

McNeill JD. Use of electromagnetic methods for groundwater studies, in Ward, S. H., Ed., Geotechnical and environmental geophysics. Soc. of Expl. Geophys. 1990;1:191–218.

Telford WM, Geldart LP, Sheriff RA. Applied geophysics, 2nd edition: Cambridge Univ. Press; 1990.

Burger HR. Exploration geophysics of the shallow subsurface: Prentice-Hall, Inc.; 1992.

Olorunfemi MO, Afolayan JF, Afolabi O. Geoelectric/Electromagnetic VLF Survey for groundwater in a basement terrain: A case study. Ife Journal of Science. 2004; 6(1):74-78.

Olayinka AI. Electromagnetic profiling and resistivity soundings in groundwater investigation near Egbeda, Kabba, Kwara State. Journal of Mining and Geology. 1999;27(2):243-250.

Omosuyi GO, Adeyemo A, Adegoke AO. Investigation of groundwater prospect using electromagnetic and geoelectric sounding at Afunbiowu, near Akure, Southwestern Nigeria. Pacific Journal of Science and Technology. 2007;8(2):172-182.

Sundrarajan N, Nandakumar G. Narsimhachary M, Ramam K, Srinivas Y. VES and VLF—an application to groundwater exploration, Khammam, India., The Leading Edge. 2007;708-716.

Zohdy AAR. Earth resistivity and seismic refraction investigation in Clara County, California, PhD thesis (unpublished). Stanford University. 1964;131-135.

Dahlin T, Zhou B. Gradient and midpoint referred measurements for multichannel 2D resistivity imaging. Proc. 8th meeting of the environmental and engineering geophysics. Aveiro, Portugal; 8-12 September. 2002;157-160.

Abudulawal L, Amidu, Sakiru A, Apanpa KA, Adeagbo OA, Akinbiyi OA. Geophysical investigation of subsurface water of Erunmu and its environs, Southwest Nigeria using electrical resistivity methods. Journal of Applied Sciences. 2015;15(5):741-751.

Karous M, Hjelt SE. Linear filtering of VLF dip-angle measurements: Geophysical Prospecting. 1983;31:782-794.

Benson AK, Payne KL, Stubben MA. Mapping groundwater contamination using DC resistivity and VLF geophysical methods - a case study. Geophysics. 1997;62:80-86.

Ogilvy RD, Lee AC. Interpretation of VLF-EM in phase data using current density pseudosections. Geophysical Prospecting. 1991;39:567-580.

Olorunfemi MO, Mesida EA. Engineering Geophysics and its application engineering site investigations (case study from Ile-Ife area). The Nigerian Engineer. 1987;22(2): 57-66.

Osuagwu BC. Geophysical investigation for groundwater in a difficult terrain around Modomo Area, Ife, Osun State: Unpublished Bachelor of Science Thesis, Obafemi Awolowo University, Ile-Ife, Osun State. 2009;88.

Olorunfemi MO, Fasuyi SA. Aquifer types and Geoelectrical / hydrogeologic Characteristics of Central Basement Terrain of Nigeria. Journal of African Earth Science. 1993;16:309-317.

Sharma SP, Baranwal VC. Delineation of groundwater – bearing fractured zones in a hard rock area integrating Very Low Frequency Electromagnetic and Electrical Resistivity data. Journal of Applied Geophysics. 2005;57:155–166.

Dan-Hassan MA, Olorunfemi MO. Hydro-geophysical investigation of a basement terrain in the North-Central part of Kaduna State, Nigeria. Journal of Mining and Geology. 1999;12:189-206.

Omosuyi GO, Ojo JS, Enikanselu PA. Geophysical investigation for groundwater around Obanla – Obakekere in Akure Area within the basement complex of southwestern Nigeria. Journal of Mining and Geology. 2003;39(2):109–116.