Estimation of saturated hydraulic conductivity <i>K</i>_<i>s</i> from the van Genuchten shape parameter <i>α</i>

Abstract

A simple relationship to estimate the saturated hydraulic conductivity K s from the van Genuchten shape parameter α is presented. The derivation of the relationship is based on the assumption that the porosity of the soil can be represented by a group of parallel capillary tubes with a fractal cumulative size distribution of pores. The proposed expression of K s ( α ) reduces the number of independent van Genuchten parameters from five to four and permits determination of all model parameters directly from water content data, avoiding measurements of saturated hydraulic conductivity. Estimated values of K s for major soil textural groups are in very good agreement with average values obtained by Carsel and Parrish (1988).