Hydrogeophysical Evaluation of Parts of River Mamu Sub-Basin, Southeastern Nigeria

Abstract

Hydrogeophysical evaluation of parts of River Mamu Sub-Basin, Southeastern Nigeria was carried out using the Vertical Electrical Sounding technique (VES). Schlumberger array was used to acquire thirty (30) VES stations and were interpreted using software 1D-Interpex. The predominate VES curve types within the area are typically K-curves which is about 47%, whereas, the remaining 53% belongs to the other five curve types namely; KH, HK, H, Q, and KHK-curves. The calculated Da-Zarrouk parameters outcomes ranged from low to high within the study area: longitudinal conductance (0.0028-0.0571 mhom); transverse resistance (6630-10290 ohm-m2); aquifer resistivity (455-4900 ohm-m), aquifer thickness (4.70-38.00 m); depth to the aquifer (33-172 m); conductivity (0.0002-0.0022 mho. Two aquifer parameters were computed within the area namely; hydraulic conductivity (6.137-0.792 m/day) and transmissivity (1.007-20.597 m2/day). Two major aquifer systems were obtained specifically; a shallow aquifer belonging to Nanka Sands with depth (33-62m) and a far aquifer belonging to Ebenebe Sandstone with depth (69-172m). The groundwater flow paths within the study area trend predominantly in the NW-SE direction. The findings revealed that the study area possesses high groundwater potentials in some areas, hence, it is more economical to drill a borehole at the southwestern part of the study area than the southeastern part.