SUBSURFACE INVESTIGATION FOR GROUNDWATER POTENTIAL OF BIU PLATEAU BASALT NORTH EASTERN NIGERIA, USING VERTICAL ELECTRICAL SOUNDING
Groundwater is a very important component of water resources in nature. Since the demand of groundwater increases with population growth, it is necessary to explore groundwater more intensively. The importance of groundwater cannot be overemphasized. For this reason, the exploration for water is therefore a vital aspect of Geophysics. The resistivity method of surveying was carried out for the study of Groundwater potential in Biu town, Borno State, Nigeria. Data were acquired using the ABEM Terrameter 300C using the Schlumberger array. The data obtained were subjected to interpretation by partial curve matching and then by computer iteration and the results correlated with records from existing wells. A total of four geologic layers namely; top soil, weathered basalt, fractured basalt and fresh basement was delineated in this study. Results showed that the aquifer is located within the second and third layers comprising mainly of weathered and fracture materials. The first aquifer is the weathered basalt with resistivity ranging from 11.5 to 106.8 Ωm and thickness ranges from 2.73 to 31.32 m. while the second aquifer is the fractured basalt with resistivity ranging from 16.5 to 372.2 Ωm with thickness from 2.9 to 11.17 m. Appropriate depths to which potable water can be obtained from the various locations varies from 21.89 m to 38.33 m are recommended in this study. While depths in VES 6 and VES 7 are 10.45 m and 14.97 m are not good for groundwater exploration.