Geo-electrical investigation of subsurface water resources in Kutunku, Gwagwalada Area Council, Abuja, Nigeria (original) (raw)

In this study, data obtained with the aid of an ABEM Terameter (SAS 300C), from twenty-five Vertical Electrical Soundings (VES) stations in Kutunku, with maximum half-current electrodes spacing AB/2, of 170m and maximum half-potential electrodes spacing MN/2, of 7.5m for most of the profiles, were analysed with IPI2Win software. The analysis indicated 3 to 5 geo-electric layers where the former was predominant and the lithologic units were interpreted to consist of sandy top soil, clay/clayey sand, lateritic sand, compact laterite, weathered/fractured basement and fresh basement. Layer resistivity ranges were 1. 95 -1360Ωm, 0.4 -1723Ωm, 7.7 -180000Ωm and 71 -44878Ωm for the first, second, third and fourth layers respectively. In the same vein, layer depth ranged from 0. 6 -4.3m, 1.1 -47.3m, 3.9 -56.9m and 31.1m to undetermined depth. The second layer in most of the profiles showed conductive zones with low resistivity values ranging from 0.403Ωm to 151Ωm. In most of the profiles, the third layer manifested as the last layer, predominantly with high resistivity readings of the order of 10 3 Ωm to 10 5 Ωm with unknown depths suspected to be fresh basement rocks. In the few profiles where four geo-electric layers were detected, with the exception of VES 18, the resistivity values (in Ωm), obtained for the last layer, were of the order of 10 3 and above, with unknown depth suspected to be fresh basement rocks. Amongst the second, third and fourth layers, the second layer mostly constitute the aquifer unit in the area with weathered/fractured basement rock type. The stations of highest groundwater potential were found to be VES 2, VES 5, VES 8, VES 14, VES 21, VES 24 and VES 25 because of the thicknesses of the layers interpreted as weathered or fractured zones which ranged from 25m to 55m.