Equation for Permeability Function

The determination of unsaturated coefficient of permeability by experiment is a tedious and time-consuming process. Therefore, an indirect method using a statistical model is commonly used to predict the permeability function from the saturated coefficient of permeability, ks, and the soil-water characteristic curve.

Statistical method for determination of permeability function, Kunze et al 1968, Childs and Collis-George 1948.

Equation for best fitting permeability function, Leong and Rahardjo 1997

Equation for estimating permeability function, Zhai and Rahardjo 2015

Zhai and Rahardjo (2015) suggested that SWCC in the form of degree of saturation should be used for the estimation of the permeability function since the SWCC in the form of degree of saturation is the most analogous to the pore-size distribution function.

References

1. Zhai, Q. and Rahardjo, H. (2015). “Estimation of permeability function from the soil-water characteristic curve.” Engineering Geology, 199, 148-156. doi
2. Leong, E. C. and Rahardjo, H. (1997). “Permeability functions for unsaturated soils.” Journal of Geotechnical and Geoenvironmental Engineering, December, 123(12), 1118-1126. doi | handle
3. Kunze, R. J., Uehara, G., and Graham, K. (1968). “Factors Important in the Calculation of Hydraulic Conductivity.” Soil Science Society of America Journal, 32, 760-765. doi
4. Childs, E. C., and George, N. C. (1948). “Soil geometry and soil-water equilibria.” Discussions of the Faraday Society, 3(0), 78-85. doi