EQUATIONS FOR THE SOIL-WATER CHARACTERISTIC CURVE

The soil-water characteristic curve can be used to estimate various pa rameters used to describe unsaturated soil behaviour. A general equati on for the soil-water characteristic curve is proposed. A nonlinear, l east-squares computer program is used to determine the best-fit parame ters for experimental data presented in the literature. The equation i s based on the assumption that the shape of the soil-water characteris tic curve is dependent upon the pore-size distribution of the soil (i. e., the desaturation is a function of the pore-size distribution). The equation has the form of an integrated frequency distribution curve. The equation provides a good fit for sand, silt, and clay soils over t he entire suction range from 0 to 10(6) kPa.