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Analysis of Steady‐State Evapotranspiration from a Soil Column
Author(s) -
Whisler F. D.,
Klute A.,
Millington R. J.
Publication year - 1968
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/sssaj1968.03615995003200020009x
Subject(s) - evapotranspiration , transpiration , loam , pressure head , water table , environmental science , soil science , soil water , water flow , richards equation , hydrology (agriculture) , evaporation , geology , groundwater , geotechnical engineering , chemistry , thermodynamics , physics , ecology , biochemistry , photosynthesis , biology
Numerical analysis is applied to the steady‐state flow equation for evapotranspiration from a vertical soil column. The water uptake by the plant roots is incorporated into the flow equation as a (negative) source term. The evapotranspiration rate and its partitioning between plant transpiration and soil evaporation are specified as the top boundary condition. The lower boundary condition is a water table. The results of the analysis for a Pachappa sandy loam give pressure head, water content, source strength and soil water flux profiles. This study has (i) demonstrated that solutions to the flow equation with a source term can be obtained by numerical means, (ii) shown something of the theoretical influence of the parameters in the source term model on the flow in the soil, (iii) qualitatively indicated a transfer of water from wet soil via the root system, and (iv) indicated that the source term has little effect on the pressure head profile unless the evapotranspiration rate is about the same order of magnitude as the theoretical limiting value.