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.