HYDROGEOPHYSICAL INVESTIGATION OF OGBOJI AND ENVIRONS, ORUMBA SOUTH LOCAL GOVERNMENT AREA, ANAMBRA STATE

This study utilized the Electrical Resistivity Method through vertical electrical sounding (VES) to evaluate thickness of the aquifer, depth to the aquifer, depth of the borehole and delineate geo-electric layers in Ogboji, Orumba South Local Government Area, Anambra State, Nigeria. The study area is situated between latitudes 5°58'0"N to 6°23'0"N and longitudes 7°9'30"E to 7°11'30"E. Seven VES were conducted in different locations, using the Schlumberger electrode array with a maximum electrode spacing (AB/2) of 260m. Details about the subsurface lithologies, including overburden thickness and aquifer-bearing layer were gathered from the various VES locations in the study area using the resistivity meter, Petrozenith PZ-03. The data were processed and interpreted using Microsoft Excel software and the interpretation revealed four(4) to five(5) geo-electric layers comprising topsoil, clayey sand, dry sand, and shale. Apparent resistivity values of the layers ranged from 2.57 to 8268Ωm, with layer thicknesses varying from 0.2 to 119.7m. A good amount of saturated sand was detected at locations 6 and 7, at depths of 120 – 125 and 140m - 143m meters, respectively. The amount of shale overlying this aquifer is much and cannot easily be drilled into. Ogboji in general lacks water this is likely due to the presence of impermeable rock layers and potential tectonic disruptions, which may have prevented aquifer formation or caused groundwater depletion. These findings indicate that the area faces potential water scarcity, emphasizing the need to explore alternative water sources such as hand-dug wells, rainwater harvesting, or surface water bodies. Further geophysical investigations and sustainable water management strategies are recommended to address the region’s water supply challenges.