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Macroporosity to Characterize Spatial Variability of Hydraulic Conductivity and Effects of Land Management
Author(s) -
Ahuja L. R.,
Naney J. W.,
Green R. E.,
Nielsen D. R.
Publication year - 1984
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/sssaj1984.03615995004800040001x
Subject(s) - hydraulic conductivity , soil water , exponent , scaling , porosity , soil science , oxisol , mathematics , environmental science , geology , geotechnical engineering , geometry , linguistics , philosophy
To develop simplified methods of hydraulic characterization of field soils and effects of management, frequency distribution of macroporosity (or effective porosity) in a soil is investigated as a measure of its saturated hydraulic conductivity distribution. The effective porosity (φ e ) of a soil is related to its saturated hydraulic conductivity ( K s ) by a generalized Kozeny‐Carman equation. The exponent of this relationship is assumed to vary within a narrow range (value of 4 or 5). The equation is then combined with scaling theory to derive the frequency distribution of K s scaling factors from the φ e distribution. These concepts are tested on experimental data for two widely different soils, a mollisol and an oxisol. The φ e is defined as total porosity minus soil water content at −33 kPa pressure head. The exponent of the K s ‐φ e relationship is found to be nearly 4 for the soil‐core data of both soils, while for a smaller set of in‐situ field data for oxisol, which was within a narrow range of φ e , the value of the exponent was smaller. There was a considerable scatter in the relationships. However, with the exponent set equal to 4 or 5 the distribution of K s scaling factors derived from φ e distribution closely matched the experimental K s ‐derived distribution. The approach has a promise for large‐scale applications.