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Determining Effective Soil Water Diffusivities from One‐Step Outflow Experiments
Author(s) -
Gupta S. C.,
Farrell D. A.,
Larson W. E.
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/sssaj1974.03615995003800050011x
Subject(s) - thermal diffusivity , outflow , function (biology) , tracer , diffusion , soil science , mechanics , environmental science , thermodynamics , physics , meteorology , evolutionary biology , nuclear physics , biology
A method is developed whereby effective or weighted mean diffusivity, D̄ , can be estimated by using outflow data. These estimates can further be analyzed for soil water diffusivity, D (θ), with the help of a step‐wise function and the relationship given by Crank (1956). The suggested procedure for estimating soil water diffusivity is more accurate than previous methods because no assumption of constant diffusivity either over the pressure increment or over the length of the soil core is required. Moreover the procedure does not use the early part of the outflow curve and thus reduces the effect of membrane impedance on the estimates of D (θ). The method was tested by simulating outflow experiments on a digital computer, and using data obtained to calculate diffusivities. Our estimates of diffusivity were in better agreement with the actual diffusivities than those obtained with the earlier “one‐step” method.