An Approximate Method for Determining the Hydraulic Conductivity Function of Unsaturated Soil

摘要

A method is proposed for determining the hydraulic conductivity function of unsaturated soil. The method is based on the assumption that the conductivity-pressure head relationship, K(h), can be effectively represented by an empirical three-parameter equation. Procedure are given for evaluating the equation parameters from measurements of the soil-water characteristic, the saturated conductivity, and the infiltration rate-time relationship for an initially dry soil. Repeated numerical solutions to the Richards equation for the movement in unsaturated soil are used with a search procedure to determine the parameter values giving the minimum difference between measured and calculated infiltration rate-time relationships. Computer programs, written in FORTRAN, were developed to apply and evaluate the method. An evaluation of the proposed method using soil property data obtained from the literature showed that a good approximation of the conductivity data could be obtained for soils in which the conductivity function had the general form of the assumed relationship. (WRSIC-Abstract)