Infiltration Under Ponded Conditions: 2. Infiltration Equations Tested For Parameter Time-dependence And Predictive Use1

We analyzed six different infiltration equations—those of Kostiakov (1932), Horton (1940), Mezencev (1948), Green and Ampt (1911), Philip (19576) and Par-lange et al. (1985)—for precision, parameter time-dependence, and applicability for predictive use. The tests were carried out by comparison with reference solutions, i.e., analytical, experimental, or numerical for two different head conditions at the soil surface. The results show that all the infiltration equations but those of Kostiakov and Horton, satisfy sufficiently well the imposed precision criterion. Only one model, however, the Parlange infiltration equation, has the advantage of using parameters that are constant in time and independent of the number of data points chosen for their evaluation procedure. The parameters entering into the other algebraic infiltration equations have to be considered as fitting parameters without physical significance and representative only of the experiment for which they are determined.