Modified Green-Ampt Infiltration Model for Steady Rainfall

Abstract

AbstractThe Green-Ampt equation describing the infiltration of water into soil requires that the rainfall intensity is greater than the infiltration capacity of the soil at all times. The well-known Mein-Larson model modifies the Green-Ampt equation and attempts to avoid this restriction for infiltration of water into a homogeneous soil under rainfall of constant intensity. The rainfall intensity is considered to be less than the infiltration capacity of the soil in the initial phases of a storm. The Mein-Larson model assumes that until the time to ponding of water over the soil surface, the infiltration rate is constant and equals the rainfall intensity. This study shows that the Mein-Larson model underestimates the ponding time and that the cumulative infiltration predicted by the model is always less than the cumulative infiltration potential of the soil. To avoid these drawbacks, an alternative modification of the Green-Ampt equation is presented. In the proposed modification, the ponding time is cons...