Abstract
The predictive capability of the Green and Ampt equations for a homogeneous medium sand is then tested against results obtained from a computer-based numerical analysis of the differential equation describing water movement in unsaturated porous media. Three simulations with different rates of water table fall are described for the zero surface flux case with one of these rates also being used when an applied surface infiltration flux is included in the system. Comparisons with Green and Ampt results are then made for these simulations in terms of the discharge-time relationship, the position of the draining front with time, and the thickness of the draining capillary fringe with time. In certain cases the approximate analysis is shown to agree with the numerical simulations quite satisfactorily while in others, notably those involving a more rapid water table fall, the differences are significant.--Modified journal abstract.