Infiltration Equations Modified for Surface Effects

A series of equations were developed for predicting infiltration into soils with modified surfaces. The Green-Ampt approach was used in their development. They have the same functional form as the Green-Ampt and Mein-Larson two-stage infiltration equations to which they reduce for the case of a uniform soil profile. The equations were applied to coarse over-fine and fine over-coarse soil stratifications and showed good agreement with both observed infiltration rates and infiltration rates predicted by numerical solution of Richards' equation. The equations were also applied to an Ida silt loam soil to illustrate the magnitude of the predicted effect of surface sealing on infiltration. Analysis was performed for two different initial moisture contents, three different rainfall intensity ratios, and four different conductivity ratios.