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Transfer of Chemicals from Soil solution to Surface Runoff: A Diffusion‐based Soil Model
Author(s) -
Wallach Rony,
Jury William A.,
Spencer William F.
Publication year - 1988
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1988.03615995005200030002x
Subject(s) - surface runoff , outflow , infiltration (hvac) , hydrology (agriculture) , soil science , environmental science , diffusion , macropore , soil water , laminar flow , sink (geography) , chemistry , geology , geotechnical engineering , materials science , thermodynamics , mesoporous material , ecology , biochemistry , oceanography , physics , catalysis , cartography , geography , composite material , biology
A physically‐based diffusion and transport model is developed to describe chemical outflow concentrations during chemical removal from soil to overlying runoff water induced by continuous rainfall over the soil surface. In contrast to earlier models, movement from the soil to the runoff water is described as a liquid diffusion process to the surface, coupled to the runoff zone through a laminar boundary layer at the runoff interface with the soil surface. Within the soil, diffusion is moderated by equilibrium adsorption to solid surfaces characterized by a partition coefficient. The runoff concentration at the outlet is derived by treating the runoff zone as a wellmixed reactor, characterized by a residence time. The model was used to predict the results obtained in the experimental study of L.R. Ahuja and O.R. Lehman (1983) where infiltration was suppressed, with good agreement obtained between predicted and measured outflow concentrations when the model parameters were estimated independently using standard engineering equations from channel flow hydraulics. The model also predicted the final soil concentrations satisfactorily after runoff ceased.