A Numerical Method for Solving the Water Flow Equation in Unsaturated Porous Media

Abstract

A numerical procedure based on the MacCormack method was used for the simulation of one‐dimensional isothermal transient movement of liquid phase water in an unsaturated soil including precipitation, evaporation, and moisture removal from soil by the roots of transpiring plants. The numerical model utilized finite‐difference explicit predictor‐corrector equations and it was applied to a few flow problems. Comparison between the numerical results and laboratory or field experimental values was very promising. Our predicted values also agreed reasonably well with previously published numerical solutions. The proposed procedure was found to be easily adapted for solving the nonlinear soil‐water flow equation. However, it required only a knowledge of soil hydraulic conductivity and its water potential or diffusivity as functions of moisture content.