Green and Ampt Infiltration with Redistribution

Abstract

Distributed, physically based watershed and irrigation advance models require robust infiltration estimation capabilities. The empirical Green and Ampt (GA) equation of infiltration is a popular method for estimating infiltration. The GA parameters have physical basis and considerable prior research has focused on relating these parameters to soil textural classification. However, the original GA method is limited in that it is applicable only for a single ponding period. An explicit Green and Ampt redistribution (GAR) technique is developed herein to estimate interstorm redistribution of soil water and allow multiple ponding simulations using the GA methodology. Soil water redistribution during interponding periods is estimated using the physical constructs of water retention curves without hysteresis. A GA wetting-front suction parameter scaling function is derived for use between arbitrary soil water contents. Simulations on 11 soil textural classifications comparing the GAR method with the numerical solution of Richards equation reveal that the GAR method is a viable technique for estimating infiltration for multiple pondings with acceptable error.