A Comparison of Three Infiltration Models

ABSTRACT THREE physically based infiltration models are com-pared both in terms of theoretical development and performance. The models are an unmodified Green-Ampt-Mein-Larson (GAML-UNMOD) model, a similar model which was modified to account for entrapped air (GAML-ETA model) and a model which considers both air entrapment and air resistance effects (GAML-ART model). The GAML-UNMOD model is conceptually the simplest model but in all cases, this model failed to do a reasonable job of predicting time to surface ponding. This failure appears to be due primarily to use of un-modified saturated hydraulic conductivity values. The GAML-ETA model did a better job of predicting time to ponding on dry soils but greatly over-predicted infiltra-tion on wetter soils. The GAML-ART model did the best overall job of predicting infiltration but did tend to over-predict on wet soils. This over-prediction by all models on the wetter soils may be due in part to partial surface sealing during preceding dry runs.