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A three‐Region Analytical Model of Solute Leaching in a Soil with a Water‐Repellent Top Layer
Author(s) -
Rooij Gerrit H.
Publication year - 1995
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/95wr02431
Subject(s) - subsoil , topsoil , leaching (pedology) , groundwater , soil water , soil science , water flow , environmental science , soil horizon , flow (mathematics) , wettable powder , geotechnical engineering , hydrology (agriculture) , infiltration (hvac) , geology , materials science , mechanics , chemistry , composite material , biochemistry , physics , emulsion
When water enters a water‐repellent topsoil, fingers develop and a large part of the soil is bypassed. Therefore fingering is expected to accelerate solute leaching to the groundwater. In soils with a groundwater‐affected wettable sublayer, fingering yields a flow pattern consisting of three regions. In the top few centimeters, water flow converges toward the finger top. In the finger, water moves vertically downward. In the wettable subsoil the flow diverges due to matric forces. Analytical steady state solutions are presented for each of these regions. The resulting model provides the breakthrough curve of a pulse of an inert solute and reveals the influence of each region. Calculations showed that the enhancement of leaching caused by fingers could be largely undone by a thick (0.75 m) wettable subsoil. A very thin (0.05 m) wettable subsoil had a much smaller effect. This illustrates the need for accurate field estimates of finger depth.