Austin C. Okonkwo and Chukwudi C. Ezeh
The electrical resistivity method has been used to characterize the groundwater hydraulics and delineate groundwater quality zones at Oduma and environs in Enugu state, Southeastern Nigeria. Oduma lies within latitudes 6â° 02Ë¡ N to 6â° 07Ë¡ N and longitudes 7â° 35Ë¡ E to 7â° 41Ë¡ E with an area extent of about 102.6sqkm. 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 Transmissivity values indicate a low yield aquifer.The established empirical relationship between earth resistivity and total dissolved solids (TDS) was used to delineate the fresh, brackish and saline groundwater zones. The various contour maps will serve as a useful guide for groundwater exploration in the study area.
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