On estimating the hydraulic properties of soil,Part 1. Comparison between forms to estimate the soil-water characteristic function

The hydraulic properties of soil include the soil-water characteristic function h(θ), in which θ is water content and h is pressure head (suction)], and the hydraulic conductivity function K(θ) or K(h)]. These functions are essential to the solution of unsaturated groundwater flow problems. A number of empirical and semiempirical forms have been proposed in the literature to estimate these functions. The present paper employs a nonlinear least-square analysis for comparison between some of the available forms, using a large number of experimental measurements of h(θ) for different classes of soil. Suitability of the forms for predicting the hydraulic conductivity function is examined. In the absence of accurate measurements, the paper facilitates modeling by providing estimates for the parameters of the soil-water characteristic function.