Preliminary Study on the Viability of Developing Borehole Water Supply System in Afugiri Community and Its Environs, Abia State, South Eastern Nigeria

Electrical resistivity method for groundwater investigation using vertical electrical sounding (VES) technique was carried out in parts of Afugiri in Umuahia-North Local Government Area of Abia State. The major aim is to delineate the aquiferous units within the study area by determining their thickness, resistivities and the potential borehole depths. The geology revealed that the study area is sedimentary environment and predominantly Bende-Ameki Formation. Prior to this study, there had been serious speculation that borehole could not thrive within the study area (mainly Afugiri). Actually, there had been no existing borehole in the area. Twelve vertical electrical soundings using the Schlumberger configuration were carried out within the study area. The data obtained were interpreted using computer software (IPI2WIN) and Surfer 8 for contouring and map production. The subsurface area investigated is made up of 5-7 geoelectric layers which are not of uniform thickness as revealed by the correlated geoelectric section. In Afugiri, the resistivity values and signatures in Vertical Electrical Sounding Stations (VES 1 and VES 3) show that they are likely to hold water at depths of 61.1 and 27.3 meters respectively. The likely aquiferous zone in VES 1 has a thickness of about 32.2 meters while the thickness of the aquiferous unit in VES 3 is about 9.61 meters. The electrical properties of VES 1 and VES 3 shows that they are likely to be sand or fractured shales. The resistivity values of the likely aquiferous zones in VES 1 and VES 3 range from about 2000 to 440,000 Ω-m. `It is recommended that boreholes be drilled much beyond the depth range of 17 m to 229 m which represent the range of water table in the study area to harness potable water within the aquifer region.