Infiltration Simulation with Improved Green-Ampt Model Coupled with the Wet Zone Partition Function

Abstract

The soil water content usually appears to be distributed in distinct layers during the process of homogeneous soil infiltration. However, existing infiltration models rarely consider the partitioning characteristics of the wet zone. The wet zone is typically assumed to be divided into a saturated zone and transient unsaturated zone during infiltration. Here, variations in the depths of the saturated zone and transient unsaturated zone during the infiltration process were studied using commercially available software. The wet zone partition function and its fitting parameters are presented. This function can characterize variations in the ratio of the saturated zone depth to the wetting front depth over time. The fitting parameters were predicted by a back-propagation (BP) neural network. The improved Green-Ampt model was established by introducing the established wet zone partition function. The infiltration results simulated by the improved Green-Ampt model, the software, and the traditional Green-Ampt model were compared with the measured values. The consistency between the measured and calculated values of the three models decreased from the improved Green-Ampt model to the software model to the traditional Green-Ampt model. The wetting front depth and the infiltration rate calculated by the traditional Green-Ampt model were larger than their measured values, which means that the effect of the transient unsaturated zone during the process of infiltration must be considered. The improved Green-Ampt model can provide analytical solutions and accurately simulate the infiltration process, which is beneficial for engineering calculations.