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First-Order Modeling of Conductivity Decay During Lateral Redistribution in a Stochastic Soil

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 141-144 in Preferential Flow, Water Movement and Chemical Transport in the Environment, Proc. 2nd Int. Symp. (3-5 January 2001, Honolulu, Hawaii, USA), eds. D. D. Bosch and K. W. King. St. Joseph, Michigan: ASAE  701P0006.(doi:10.13031/2013.2117)
Authors:   Hubert J. Montas and Adel Shirmohammadi
Keywords:   Preferential infiltration, numerical methods, nonequilibrium potential

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.

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