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Figure from:GEO-ELECTRICAL EXPLORATION FOR GROUNDWATER WITHIN THE PREMISES OF UNIVERSITY OF ILORIN TEACHING HOSPITAL, ILORIN, KWARA STATE, NIGERIA

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Van Overmeeren, R. A. (1989). Aquifer Boundaries Explored by Geoelectric Measurements ii the Coastal Plain of Yemen. A case of Equivalence. Geophysics, 54 (1): 38-48. “ Vandenberghe, J. (1982). Geoelectric Investigation of Faults in Quaternary Deposits. Geophysic: Prospecting, 30: 879-897.

Table 2 Van Overmeeren, R. A. (1989). Aquifer Boundaries Explored by Geoelectric Measurements ii the Coastal Plain of Yemen. A case of Equivalence. Geophysics, 54 (1): 38-48. “ Vandenberghe, J. (1982). Geoelectric Investigation of Faults in Quaternary Deposits. Geophysic: Prospecting, 30: 879-897.

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Electrical resistivity survey is usually designed to measure the electrical resistivity variation of the subsurface materials by making measurements at the earth surface. The common electrode arrays suitable for VES work are the Wenner and the Schlumberger arrays. In the Schlumberger array the spacing between the potential electrodes must not exceed 40% of half the distance between the current electrodes (Adewumii etal., 2005).
Electrical resistivity survey is usually designed to measure the electrical resistivity variation of the subsurface materials by making measurements at the earth surface. The common electrode arrays suitable for VES work are the Wenner and the Schlumberger arrays. In the Schlumberger array the spacing between the potential electrodes must not exceed 40% of half the distance between the current electrodes (Adewumii etal., 2005).
The resistivity values for the topsoil vary from 70 to 750 ohm-m with the highest frequencies in the 70 to 250 ohm-m range. The low resistivity end (<250 ohm-m) is diagnostic of clay / sandy-clay and clayey sand, while the high resistivity end (250 ohm-m) typifies compacted sand and laterites. The topsoil (1 layer) thickness varies from 0.29 to 1.0 m. This layer is composed of clay, lateritic clay. sandy clay, clayey sand and sand. This accounts for the wide resistivity range (Okhue and Olorunfemi, 1991).
The resistivity values for the topsoil vary from 70 to 750 ohm-m with the highest frequencies in the 70 to 250 ohm-m range. The low resistivity end (<250 ohm-m) is diagnostic of clay / sandy-clay and clayey sand, while the high resistivity end (250 ohm-m) typifies compacted sand and laterites. The topsoil (1 layer) thickness varies from 0.29 to 1.0 m. This layer is composed of clay, lateritic clay. sandy clay, clayey sand and sand. This accounts for the wide resistivity range (Okhue and Olorunfemi, 1991).