Groundwater Targeting Within The Basement Complex Rocks Of Federal Capital Territory Abuja Using Remotely Sensed And Vertical Electrical Sounding Data

ABSTRACT: Federal Capital Territory, Abuja largely falls within the North-Central Basement Complex of Nigeria, which is underlain by crystalline basement rocks. Groundwater resources in the crystalline basement complex are restricted to features produce by weathering and tectonic processes and therefore the reason to locate fracture/weathered zone to ensure maximum and sustainable yield. This study was carried out to illustrate the application of vertical electrical sounding (VES) and remote sensing techniques for efficient groundwater resources. The advent of computer software and associated numerical modeling aided such approach for groundwater exploration more especially in a regional scale. The modeling of the VES measurements carried out at Nineteen (19) stations has been used to derive the sub-surface geo-electric sections for the various profiles. Geologic sequence in the study area is composed of three to six sub-surface layers. The first layer is the top soil with resistivity ranging from 32.32- 73.1 ohm-m and a thickness range from 0.6m – 1.96m, Second layer is a lateritic layer ranging from 112.6 to 190.8 ohm-m with a thickness range of 0.65 to 1.96m, weathered basement ranging from 68.26 to 796.4 ohm-m with thickness range of 2.96 to 5.44m as the third layer. The fourth layer with resistivity value range between 50.2 to 205.6 ohm-m and thickness range of 4.23 to 43.95m is noted as the weathered/fractured basement (water bearing). The layer is extensive and thickest at VES station 5and 6, thus serve as a good reservoir for groundwater exploration. The fifth layer is presumably fresh basement whose resistivity values vary from 1049Ωm to 49334Ωm with an infinite depth