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Aquifer hydraulic characteristics, Dar - Zarrouk parameters, Resistivity, Imo River Basin, Nigeria


We have used the concept of Da - Zarrouk parameters (transverse unit resistance (R) and longitudinal conductance (C)) in porous media to determine aquifer hydraulic characteristics within the middle Imo river basin. The lithostratigraphic units within the study area include: Imo formation, Bende - Ameki formation, Ogwashi Asaba formation and Benin formation. The direct current electrical resistivity method was utilized for the present study. Twenty-four (24) vertical electrical soundings (VES) using the Schlumberger array was acquired for the study area. A maximum current electrode spacing (AB) of 1000 meters was used. Eight of the soundings were carried out near existing boreholes. A combination of curve matching techniques and computer iterative modelling was used in processing the data. Results show that the depth to water table varies between 12m at Ife and 153m at Aba Branch. Interpretative cross - section along two profiles show that aquifer thicknesses range between 9m and 104m. The diagnostic Kσ = constant value was used to delineate the different lithostratigraphic units within the study area. We have also used the established relationship between aquifer characteristics and geoelectric parameters to estimate hydraulic conductivity and transmissivity values of all the sounding locations including areas where boreholes were non - existent. Hydraulic conductivity varies between 1.24 m/day at Amuzukwu and 26.41 m/day at Obinze. Transmissivity values also vary between 41m2/day at Osuachara and 1370 m2/day at Obinze.