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Infiltration Prediction based on Estimation of Green‐Ampt Wetting Front Pressure Head from Measurements of Soil Water Redistribution
Author(s) -
Chong S. K.,
Green R. E.,
Ahuja L. R.
Publication year - 1982
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/sssaj1982.03615995004600020004x
Subject(s) - infiltrometer , infiltration (hvac) , pressure head , soil water , hydraulic conductivity , soil science , water content , field capacity , wetting , chemistry , geotechnical engineering , environmental science , thermodynamics , geology , physics
A simple, physically based algebraic equation was derived to calculate the wetting front matric pressure head, H f , in the Green‐Ampt equation of infiltration. The derivation of the equation involved combining the simple hydraulic conductivity function with the wetting front matric pressure head function proposed by R. G. Mein and C. L. Larson (1971). The parameters in the derived equation were determined from fitting a power function to the experimental data of soil water content and soil water pressure head vs. elapsed time obtained during the post‐infiltration redistribution period. In the derived equation, H f is expressed as a function of antecedent soil water content. At low initial water contents, the equation shows that H f is essentially a constant. Evaluation of the calculated H f values was accomplished by utilizing H f in the Green‐Ampt equation to predict infiltration at seven field sites for soils at initial water contents below field capacity. Predicted cumulative infiltration was compared with infiltration measured with a double‐ring infiltrometer. The resulting Green‐Ampt predictions were accurate for initially dry soils, with a correlation value of r = 0.94 and a relative error of 12.1%.