Authors : A.C. Ekwe, I.N. Nnodu, K.I. Ugwumbah and O.S. Onwuka
Abstract: Geo-electrical measurements using the Vertical Electrical Sounding (VES) method was utilized in determining aquifer characteristics of Oduma. Three geologic groups were delineated: Albian Asu River Group, Turonian Eze- Aku Group and Coniacian Awgu Group. Eight VES results using the Schlumberger configuration were acquired for the study area. A maximum half electrode spacing of 300 m was utilized for data acquisition. Eight soundings were processed using RESIST software. Geo-electric sections were generated from which the aquiferous layers were delineated and hydraulic parameters (hydraulic conductivity and transmissivity) were computed. The layer parameters obtained were used to calculate longitudinal conductance (S) and transverse resistance (R) variations in the study area. Data analysis was done based on Niwas and Singhal’s established relationship between aquifer transmissivity (T) and Dar Zarrouk’s parameters-R and S to calculate hydraulic conductivity and Transmissivity distribution in the study area. Knowledge of aquifer parameters from pumping test carried out on bore wells combined with existing litho-logs aided correlation of geo-electric sections to litho-logs. Results from geosounding interpretation show that transmissivity ranges between 14.17 m2 day-1 at Obufia Ohofia and 174.89 m2 day-1 at CSS Ohafia Oduma. Hydraulic conductivity ranges between 0.6243 m day-1 at Obufia Ohofia and 5.5091 m day-1 at Obodo Uhuanwuta. The depth to water table ranges between 6.7 m at Umuichite Obeagu to 32.7 m at CSS Ohofia while aquifer thickness ranges between 12.0 m at Umuichite Obeagu and 118.9 m at CSS Ohofia Oduma.
A.C. Ekwe, I.N. Nnodu, K.I. Ugwumbah and O.S. Onwuka, 2010. Estimation of Aquifer Hydraulic Characteristics of Low Permeability Formation from Geosounding Data: A Case Study of Oduma Town, Enugu State. Online Journal of Earth Sciences, 4: 19-26.