Application of resistivity method to study the potential zones for groundwater in ten selected locations of Osogbo, South-West of Nigeria

O.O. Alabi, S.O. Sedara

Abstract



Background: Vertical Electrical Sounding (VES) using Schlumberger array was carried out at ten (10) VES stations in Osogbo Local Government Area namely Oke-Ijetu ( N7℃ 73' 81.0'' , E4℃ 56' 00. 4'' ) ; Oke - Oniti (N7℃ 79' 02.0'' , E4℃ 56' 59.0'' ); Ataoja (N7℃ 76' 66.2'', E4℃ 55' 77.6'' ) ; Kelebe (N7℃ 79'68.5' ' ,E4℃58'52.2'' ) ; Kobo-n-gbogbo-e (N 7℃ 82' 12.7'', E4℃ 60' 34.7'') ; Agunbelewo (N7℃ 80' 36.3'' , E4℃ 52' 97.4'' ) ; Zone9 (N7℃ 77' 24.1'', E4℃ 59' 67.9'' ); Ogo-Oluwa (N 7℃ 73' 62.3'' , E4℃ 52' 44.3'' ) ; Alekuwodo ( N7℃ 70' 55.0'' , E4℃ 53' 4 2.4'' ) and G.R.A .(N7℃ 79'99.1'',E4℃ 52'54.0'') for ground water exploitation.
Methods: The field data obtained was analyzed using computer software (WINRES Version 1.0) which gives an automatic interpretation of the apparent resistivity with corresponding thickness and depth.
Results: The VES results revealed various characteristics of the subsurface geological sequence. It also revealed structure of three to six geo-electric layers of resistivity ranging from 23.1 Ùm to 13976.1 Ùm, thickness range from 0.4 m to 30 m and depth from 0.4 m to 55 m. The study area is composed of top soil, weathered layer, partially weathered and fresh basement.
Conclusion: The result showed that the potency of groundwater in some of these locations based on this method is good for domestic water supply and also for irrigation taking into consideration the longitudinal conductance (s) which zoned the areas into good (s>0.5), intermediate (s<0.4) and poor (s<0.1) which reflected that about 90% of the locations are intermediate for ground water potential and so groundwater improvement in the study area would be feasible if fully penetrated.

Keywords


Vertical Electrical Sounding, groundwater, fresh basement, apparent resistivity, longitudinal conductance

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