Aquifer delineation in parts of Akwa-Ibom State, Southern Nigeria using Resistivity Survey

In line with Sustainable Development Goals (SDG 6.6), aquifer delineation in parts of Akwa-Ibom State, Southern Nigeria was carried out using resistivity survey. The areas covered in the study included Uyo, Itu and Ibiono Ibom. Electrical resistivity technique was applied to obtain data from the subsurface layers. The study utilized a Signal Averaging System (SAS) 1000 Terrameter, four stainless steel electrodes, four reels of cable, geologic hammer, a measuring tape and a Global Positioning System (GPS). A SAS 1000 Terrameter was used in measuring the resistivity of the materials within the subsurface. Electric current was transmitted into the ground from the Terrameter using current electrodes while the potential difference between the current electrodes was measured. A total of four (4) stainless steel electrodes were used: two (2) current electrodes which transmitted electric current into the ground and two (2) potential electrodes from which the potential difference was measured between the current electrodes. Four reels of cable were used to link the electrodes and the Terrameter. The cable served as conductor of electric current into the ground. A total of four geologic hammers were used in sending the electrodes into the ground and in making them to be firmly fixed. A 100-m measuring tape was used to determine the intervals between the current electrode and potential electrode. A total of nine (9) ERT data points were obtained, processed and interpreted. The data obtained from the field were processed and also interpreted from curve matching techniques together with computer-aided software called Interplex 1-D. Deeper aquifers free from surface contamination and suitable for groundwater development are encountered at depth ranges of 90 m to 120 m, 70 m to 130 m, 80m to 160m and 70 m at Uyo, Itu, Ibiono Ibom and Ibesikpo respectively. The depths to aquifer, thicknesses and resistivity values were 1.086-445m, 1.086-248m and 0.114-8,132 Ωm, and 1.45-378m, 1.45-348m and 203-5,229Ωm, and 1.345-863.8m, 1.345-422.5m and 202.5-445.3Ωm, and 1.464-66.61m, 1.464-41.99m and 90.85-695.4Ωm in Uyo, Itu, Ibiono Ibom and Ibesikpo Asutan respectively. Borehole drilling within the locations where survey was carried out should target the depths of the delineated aquifers is recommended.