Abstract

This work evaluates the use of geoelectrical method in the delineation of potential groundwater zones at Oduma in Enugu state, Southeastern Nigeria. Oduma lies within latitudes 6°02Ë¡ N to 6°07Ë¡ N and longitudes 7°35Ë¡ E to 7°41Ë¡ E with an area extent of about 102.6 km². The area is underlain by Awgu Shale group with its lateral arenaceous facie; Owelli Sandstone outcropping south of Oduma. Thirteen (13) vertical electrical soundings (VES) were carried out within the study area. Interpretated VES data shows predominance of Q and H curve type, indicating a fracture-shale subsurface. Contour maps of iso-resistivity, depth, transverse resistance, longitudinal conductance, aquifer transmissivity and hydraulic conductivity were constructed. Computed aquifer transmissivity from VES data values indicates a low yield aquifer. The latter was used to delineate the potential groundwater zones based on Gheorge aquifer transmissivity classifications. Comparisons of aquifer hydraulics estimated from geoelectrical sounding and the pump test analysis indicates a fairly good match. Three potential groundwater zones were delineated; the low, very low and negligible potential zones. The various contour maps and potential groundwater zone map will serve as a useful guide for groundwater exploration in the study area.

Key words: Resistivity, transmissivity, hydraulic conductivity, groundwater zones, aquifer yield.