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Improved evaluation procedure for heat‐pulse soil water flux density method
Author(s) -
Kluitenberg G.J.,
Warrick A.W.
Publication year - 2001
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/sssaj2001.652320x
Subject(s) - series (stratigraphy) , range (aeronautics) , aquifer , flux (metallurgy) , groundwater , function (biology) , pulse (music) , approximation error , soil science , heat flux , mathematics , environmental science , mechanics , geotechnical engineering , physics , heat transfer , geology , materials science , paleontology , optics , evolutionary biology , detector , metallurgy , composite material , biology
Analytical solutions of the heat equation must be evaluated in order to implement the heat‐pulse method for measuring soil water flux density. We developed an improved procedure for evaluating the integrals in these solutions by recognizing that they can be reduced to a single function, W , known as the well function for leaky aquifers The evaluation procedure was improved further by developing an efficient method to approximate W This method, which involves summing the first few terms of an infinite series, also provides a simple means of determining the approximation error. For a wide range of input parameters, at most two terms of the series are needed to approximate W with error less than 10 −4 in absolute value. Thus, numerical integration is not required in order to implement the heat‐pulse method for measuring soil water flux density. Our results regarding the evaluation of W are relevant to other problems in soil science and groundwater hydrology in which the function W appears.