A Comparative Study of Two Methods for Modeling Soil Water Regime in Agricultural Fields

Two methods widely used in agrometeorogical simulation models for describing field soil water regimes are compared and evaluated based on their ability to predict experimental data from a single field study. The first method is based on a numerical solution to the Richards' equation for describing water movement in the soil profile, while the second method is based on soil-water capacity terms. The evaluation of the performance of the two methods is based on goodness-of-fit statistics and graphical analysis. Results indicate that the first method is more accurate for both the upper and the lower soil zones; the second method, despite its low performance in the upper soil zone can adequately describe soil moisture conditions in the lower soil zones. Recommendations are made for model use based on comparison results, the intended model use, and the difficulty in the acquisition of required model inputs.