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United States Department of Agriculture

Agricultural Research Service

Title: Predicting Unsaturated Hydraulic Conductivity from the Gregson Hector-Mcgowan One-Parameter Water Desorption Model


Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 27, 1999
Publication Date: June 25, 1999

Technical Abstract: Determining soil water characteristics is both laborious and time- consuming, but is necessary for many soil management evaluations and for modeling purposes. The Gregson-Hector-McGowan model uses information about the relationship between the slope and intercept of a log-log plot of the ( ) curve to improve predictions of soil water retention characteristics from limited data. We found that the model gave reasonably accurate predictions of the water retention curve from the knowledge of one ( ) point and generalized slope-intercept relationships for several Ohio, Iowa, and Colorado soils. We explored the possibility that a similar relationship exists for the unsaturated hydraulic conductivity function [K( )]. A strong correlation (r2 >0.9) was found between the slope and intercept of individual log-log plots of the K( ) curve. It appears that a generalized slope-intercept relationship, as is found with ( ) curve, also exists for the K( ) function. We use this information with various models to predict unsaturated hydraulic conductivity from limited data.

Last Modified: 4/22/2015
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