A new method to estimate soil water infiltration based on a modified Green-Ampt model

Water infiltration is an important component of overland hydrology, closely related to the amount of water that penetrates into soil, overland flow, soil erosion, and chemical transport. The Green-Ampt infiltration equation is one of the most widely used infiltration equations in hydrological and erosion models. The piston assumption in the model simplify the soil moisture distribution and overestimated the values at the mean time. A new model for predicting the soil water content distribution along a horizontal soil column and a related algorithm for soil water infiltration rate estimation are presented. Two linear functions were used to replace the even distribution of soil water content in the vadose zone and the wetting front, as traditionally used in the Green-Ampt infiltration model. The new algorithm for soil water infiltration rate estimation was based on a new soil water content distribution model. Laboratory experiments were conducted with three soils (sandy loam, silt loam, and silty clay loam) to illustrate the infiltration estimations experimentally. The relative errors of the method calculated based on the water/mass balance principle were 2.05%, 4.75%, and 1.92% for sandy loam, silt loam, and silty clay loam soil, respectively. Changes in the relative errors over time were also analyzed. This new, highly precise method can be applied to infiltration and groundwater modeling studies, as well as irrigation and drainage management.