CORRESPONDENCE OF HYDRAULIC FUNCTIONS FOR UNSATURATED SOILS

This study investigated the correspondence of hydraulic functions for unsaturated soils. The overall idea was to identify general properties and explore conditions for which alternative functions give the same or similar responses. Five commonly used empirical forms were examined in this context. The objective was to extend solutions based on parti cular forms of hydraulic models to more general conditions. For exampl e, the commonly applied formula for steady-state flow of a disk infilt rometer assumes a quasi-linear form of Richards' equation. Another are a of application is parameter identification and the choice of alterna tive models. In order for two sets of models to correspond, the zeroth and first moments of the soil water diffusivity, D, should be equal f or the respective models. The zeroth moment is simply the integral of D with respect to water content across the range of interest and is cl osely related to sorptivity and capillary length. The first moment cha racterizes the shape of D.