Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

This study evaluates the ability of a first-order approximation to describe the decay of nonequilibrium potential and hydraulic conductivity during lateral redistribution of water after a preferential infiltration event. Lateral redistribution experiments are performed numerically on isotropic and anisotropic stochastic soils, using the finite element method. In each case, the moisture is initially located in larger pores and slowly moves into smaller pores due to capillary pressure gradients. Predictions of the first-order approximation are compared to those of detailed simulations. The approximation replicates the trends of the detailed simulations very well, without parameter adjustment, but may overestimate preferential flow effects when disequilibrium is strongest. Its simplicity makes the first-order approximation valuable for the development of upscaled equations.