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Stability of the Green‐Ampt Profile in a Delta Function Soil
Author(s) -
Milly P. C. D.
Publication year - 1985
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/wr021i003p00399
Subject(s) - hydraulic conductivity , infiltration (hvac) , water content , richards equation , soil science , wetting , conductivity , moisture , delta , geotechnical engineering , environmental science , mathematics , materials science , geology , soil water , thermodynamics , chemistry , physics , composite material , astronomy
The sharp wetting front of Green and Ampt represents a solution of the Richards equation for infiltration into a delta‐function soil. In order that the sharpness of this profile be maintained in the presence of a small perturbation of the profile shape, it is sufficient that the second derivative of hydraulic conductivity with respect to moisture content be positive for all values of moisture content. An inspection of theoretical and experimental data on the hydraulic conductivity suggests that this condition is usually satisfied. The profile is also stable if the first derivative of hydraulic conductivity with respect to moisture content is proportional to a delta function.