Hydrogeophysical investigation of Southern Anambra Basin Nigeria

This study was undertaken to study the hydrogeophysical properties of the geologic formations that underlie the Southern Anambra Basin and to help in delineating sites for drilling of productive boreholes in the area. The North-south trending Awka-Orlu cuesta divides the study area into two relief features, viz; the western uplands underlain by the Eocene Ameki Formation and the Miocene Ogwashi-Asaba Formation and the eastern lowlands underlain by the Paleocene Imo shale Formation. Surface water is uncommon in the western uplands. Forty-two Schlumberger electrical soundings were carried in the study area to a maximum current electrode separation of 1200m. Eleven of the soundings were conduct besides boreholes already drilled in the area. From the data, variations of the depth to the water table, longitudinal conductance, transverse resistance and the thickness of the aquiferous layer have been established. The analytical relationship between the Dar Zarrouk parameters and the hydraulic characteristics were used to assess the hydrogeological condition of the basin. These have led to inferences about the aquifer hydraulic conductivities and transmissivities and K product across the area. Consequently favourable areas have been suggested for future groundwater development in the area. Hydrochemical analysis carried out on the water samples indicates that the water samples are suitable for human consumption as well as for industrial uses. KEY WORDS: Hydrogeophysical, Aquifer, Hydrochemical, Groundwater. Global Journal of Geological Sciences Vol.2(2) 2004: 221-23