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Title: AN EQUATION FOR DESCRIBING SOLUTE TRANSPORT IN FIELD SOILS WITH PREFERENTIAL FLOW PATHS

Author
item STEENHUIS, T
item KIM, Y
item PARLANGE, J
item AKTAR, M
item RICHARDS, B
item KUNG, K
item Gish, Timothy
item DEKKER, L
item RITSEMA, C

Submitted to: Preferntial Flow Water Movement and Chemical Transport in the Environment
Publication Type: Proceedings
Publication Acceptance Date: 12/20/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Modeling solutes under field conditions is cumbersome due to presence of preferential flow paths and the input data needed to describe these paths. We propose a simple equation that can predict the breakthrough of solutes without excessive data requirements. Conceptually the soil is divided in a distribution layer and a conveyance zone. The distribution zone act as a linear reservoir resulting in an exponential loss of solutes from this zone. In the conveyance zone the transport of solutes is described with the convective dispersive equation. Input data required are apparent water content of the distribution zone and solute velocity and dispersion in the conveyance zone. The model with these three parameters was able to describe the breakthrough of solutes through undisturbed columns.

Technical Abstract: During the past two decades, scientists and regulatory agency have been unable to accurately simulate chemical transport in field soils. The major limitation to present water quality models is their inability to describe a process referred to as preferential flow. Preferential flow arises from water and chemical flow in old root channels, worm holes or from flow instabilities. This paper utilizes a relatively simple approach for describing chemical transport in soil, including preferential flow. The model successfully simulated the transport of a mobile chemical, chloride, in 39 undisturbed sandy loam soil columns. This model may benefit water quality modelers as it has the capacity to describe chemical transport through soils and does not require and extensive set of input parameters.