Evaluation of Empirical Formulae for Determination of Hydraulic Conductivity based on Grain-Size Analysis

Several empirical equations to calculate hydraulic conductivity using grain size distribution of unconsolidated aquifer materials have been evaluated in this study. Grading analysis of soil samples extracted from test holes during groundwater investigation project was performed to determine their classification and particle size distribution characteristics; from which hydraulic conductivities were computed. Results showed that all the seven empirical formulae reliably estimated hydraulic conductivities of the various soil samples well within the known ranges. Kozeny-Carman formula proved to be the best estimator of most samples analyzed, and may be, even for a wide range of other soil types. However, some of the formulae underestimated or overestimated hydraulic conductivity; even of the same soils. Alyamani and Sen formula in particular is very sensitive to the shape of the grading curve, hence the need to be very careful when using. Most importantly, all these empirical formulae are to be used strictly within their domains of applicability. (The Journal of American Science. 2008;4(1):1-6). (ISSN: 1545-1003).