Parameter optimization of Green and Ampt equation using a nonlinear algorithm

Abstract

Introduction: The Richards equation or a simplification, such as the Green and Ampt equation, is mainly used to describe the flow of water in the soil. The Richards equation produces accurate results, but lacks general analytical solutions, so the Green and Ampt equation is used as an intermediate way of modeling the phenomenon by maintaining physical-mathematical bases in the representation.Objective: To optimize the parameters of saturated hydraulic conductivity and wetting front suction of the Green and Ampt equation by means of a nonlinear optimization algorithm, and to validate the solution to optimize the parameters as a function of soil textures.Methodology: The Levenberg-Marquardt algorithm was used to estimate the infiltration parameters of the Green and Ampt equation, and the initial pair of values was taken according to soil texture.Results: This model was used to calculate the hydraulic conductivity parameters at saturation and wetting front suction.Study limitations: A homogeneous soil column and a constant initial moisture content were considered for the whole column.Originality: The optimization algorithm was oriented to keep the parameter values within the range established in the textural classes.Conclusions: An optimization algorithm was implemented to estimate the parameters Ksand hfby solving the Green and Ampt equation, which included code performance review and experimental validation with infiltration tests.