Implementation of the Green-Ampt Infiltration Model: Comparative between Different Numerical Solutions

Abstract

The phenomena of infiltration and the percolation of water in the soil are of fundamental importance for the evaluation of runoff, groundwater recharge, evapotranspiration, soil erosion and transport of chemical substances in surface and groundwater. Within this context, the quantitative determination of the infiltration values is extremely important for the different areas of knowledge, in order to evaluate, mainly the surface runoff. Several types of changes in vegetation cover and topography result in significant changes in the infiltration process, making it necessary to use mathematical models to assess the consequences of these changes. Thus, this paper aims to implement the Green-Ampt model using two numerical methods-Newton-Raphson method and W-Lambert function-to determine soil permeability parameters-K and matric potential multiplied by the difference between initial and of saturation-ψ∆θ comparing them to the real data obtained in simulations using an automatic rainfall simulator from the Federal University of Goiás-UFG. The Green-Ampt model adjusted well to the data measured from the rain simulator, with a determination coefficient of 0.978 for the Newton-Raphson method and 0.984 for the W-Lambert function.