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Deterministic and Stochastic Prediction of Atrazine Transport in Soils Displaying Macropore Flow

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

Citation:  Pp. 133-136 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:10.13031/2013.2133)
Authors:   A. Shirmohammadi, H. Montas, L. Bergstrom, K. Coyne, S. Wei, and T. Gish
Keywords:   modeling, macropore flow, deterministic, stochastic

Preferential flow plays a dominant role in water and chemical transport. However, the main challenge remains to be its inclusion in the water quality models. Tension infiltrometer data indicated a pronounced macropore flow under both conventional and no-till systems in a sandy loam soil in Maryland. Models used to perform the simulations of atrazine transport included a management model, GLEAMS, a mechanistic model, MACRO, and a stochastic model. Results indicate that GLEAMS model provided reasonable prediction of the atrazine in top 30 cm, but failed to trace it down to the deeper depths. Macro model's two-domain component provided reliable results in the upper soil profile where macropores dominate. The stochastic approach was able to predict peak arrival times at 150 cm with a great accuracy for fields with slow release compound regardless of tillage. This study concluded that stochastic approach captures the field heterogeneity better than the deterministic models.

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