Two-Dimensional Exponential Infiltration Equations

Physical two-dimensional infiltration equations expressed in exponential form were developed based upon the four time intervals derived in an earlier study for one-dimensional infiltration. Assumptions that the loci of the wetting pattern for the two-dimensional infiltration are half-ellipses, and that their vertical and horizontal flow components can be described as one-dimensional infiltration. The developed equations were checked by laboratory experiments using the soil-box method at two (dry and wetter) soil-moisture levels. These experiments were conducted at the two controlled soil-moisture levels using aa clay-loam as a soil medium. For the dry soil moisture level, the computed and the measured infiltration rates were considered in good agreement (-1- 11). However, in the wetter soil-moisture level, the computed infiltration rates were smaller, by as much as -56, than the measured infiltration rates until 150 minutes of the infiltration time. The former were as much as 14% larger than the latter, ranging from 150 min. - 330 min. of the infiltration time. The results, in general, show good agreement in both soil samples considering only the arithmetic differences between the measured infiltration rates and the computed ones. The assumptions made in the derivation of the two-dimensional infiltration equations were found to be responsible to some extent. However, the discrepancy warrants further investigations and a table of experimental data is provided for such further work.