MODELING INFILTRATION INTO A SEALING SOIL

Rain infiltration is often controlled by a less permeable layer known as a seal. Infiltration through this layer was modeled numerically by continuously updating the seal properties as a function of rainfall characteristics. The seal remains unchanged until the surface has reached incipient ponding. Subsequently, a rapid change in the hydraulic properties of the seal is imposed to reflect the effect of raindrop impact. Finally, an equilibrium state develops between seal formation due to raindrop impact and seal erosion due to the rainstorm intensity effects. Model‐predicted infiltration was similar to that observed during simulated rainstorms having various combinations of intensities and kinetic energy rates per millimeter of rain. A sensitivity analysis was performed to determine the effects of changes in seal and bulk soil properties, as well as simulation parameters, on infiltration. Seal formation was dependent on cumulative rainfall energy and the rainstorm intensity. Copyright 1990 by the American Geophysical Union.