Comparative Study of the Aquifer Transmissivity and Hydraulic Conductivity Values From Different Methods. Case Study Agbani Sandstone, South Eastern, Nigeria

The aquifer transmissivity and hydraulic conductivity values of Agbani Sandstone was investigated using different statistical and pumping test approaches developed by different authors. A total of three (3) boreholes was constructed during the time of this study and it was used to determine aquifer characteristics of Agbani Sandstone. The depths to water table vary from 80 - 120 m and the results of transmissivity (T) values obtained from various approaches varies from 0.883 to 2.855 m2h-1 for Step-drawdown; 65.84 to 72.19 m2h-1 for Theis’s recovery; 2.39 to 3.65 m2h-1 for Jacob’s method and from 8.48 to 12.94 m2. The hydraulic conductivity (K) values obtained from different statistical methods varies from 2.15 – 2.39 mh-1 for Harleman et al. (1963); 18.3 – 19.3 for Hazen (1893); -0.18 to -0.32 mh-1 for Masch and Denny (1966) and 1.09 to 1.16 for Uma (1984) while those calculated from various pumping test fluctuates between 0.003 to 0.010 mh-1 for Step-drawdown; 0.0004 to 0.008 mh-1 for Theis’s recovery; 0.015 to 0.043 mh-1 for Jacob’s and 0.039 to 0.083 mh-1 for Logan’s procedures. There is a good correlation for the calculated transmissivity between the Theis and Jacob’s approaches and Logan’s and Jacob’s method (R2 = 0.99 and 0.92, respectively).It was discovered that the statistical method developed by Masch and Denny (1966) and Uma (1984) yielded results that were as accurate and consistent as Logan's and other pumping-test techniques.