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Flux‐Gradient Relationships and Soil‐Water Diffusivity from Curves of Water Content versus Time
Author(s) -
Nofziger D. L.,
Ahuja L. R.,
Swartzendruber D.
Publication year - 1974
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/sssaj1974.03615995003800010014x
Subject(s) - thermal diffusivity , flux (metallurgy) , soil science , computation , interpolation (computer graphics) , water content , mechanics , function (biology) , soil water , boundary (topology) , mathematics , mathematical analysis , geometry , environmental science , geology , geotechnical engineering , materials science , computer science , algorithm , physics , thermodynamics , animation , computer graphics (images) , evolutionary biology , biology , metallurgy
Direct analysis of a family of curves of soil‐water content versus time at different fixed positions enables assessment of the flux‐gradient relationship prior to the calculation of soilwater diffusivity. The method is evaluated on both smooth and random‐error data generated from the solution of the horizontal soil‐water intake problem with a known diffusivity function. Interpolation, differentiation, and integration are carried out by least‐squares curve fitting based on the two recently developed techniques of parabolic splines and sliding parabolas, with all computations performed by computer. Results are excellent for both smooth and random‐error input data, whether in terms of recovering the original known diffusivity function, assessing the nature of the flux‐gradient relationship, or in making the numerous checks and validations at various intermediate stages of computation. The method applies for any horizontal soil‐wetting process independently of the specific boundary conditions, including water entry through a nonzero inlet resistance. It should be adaptable to horizontal dewatering, and extendable to vertical flow.