TESTING OF APPROXIMATE EXPRESSIONS FOR SOIL-WATER STATUS AT THE SURFACE DURING INFILTRATION

Approximate expressions for the water content at the soil surface during constant flux infiltration and for the time to ponding under a range of constant surface fluxes are tested using a well-established computer-based numerical approach which has recently been validated against exact analytical solutions. The expression for the surface water content shows agreement to within 1% over the entire time range simulated. For the time to ponding case, it is found that a geometric mean of the data from equations defining coarse upper and lower bounds of ponding time provides an easy and accurate estimate of the ponding time.