THE APPLICATION OF GEOELECTRIC SURVEY TECHNIQUE TO EVALUATE AQUIFER POTENTIALS AND ITS PROTECTIVE CAPACITY IN PARTS OF THREE ARMS ZONE, MINNA, NORTH-CENTRAL NIGERIA

Abstract

Geoelectric survey was carried out in part of Three Arms Zone Minna, north central Nigeria. The aim of the survey is to evaluate the aquifer potential of the area and its protective capacity. Forty eight vertical electrical sounding stations were investigated across the area. Schlumberger electrode configuration with maximum current electrode spacing (AB/2) of 100 m was employed. The area was gridded into six profiles with profile separations of 100 m and VES spacing of 100 m apart. Two to four geologic layers were delineated from the interpreted results. The geoelectric layers of the subsurface shows topsoil with resistivity range from 2.1 to 434.4 Ωm. Weathered/fractured basement layer resistivity range from 20.4 to 4491.1 Ωm and Fresh basement resistivity ranging between 1,021.4 and 19,418.4 Ωm. The weathered/fractured layer is considered as the major aquiferous zone. Iso-resistivity and longitudinal conductance maps were produced. Eight VES points were consider as the aquifer potential of the area having weathered/fractured resistivity varying between 108.5 Ωm and 647.1 Ωm with thickness range from 11.8 m to 30.7 m. The longitudinal conductance value ranges from 0.002642 Siemens to 2.340909 Siemens. The protective capacity evaluated shows that about 50% of VES points are poorly protected, 14.48% are weakly protected, 22.92% are moderately protected and 12.50% have good protective capacity.