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United States Department of Agriculture

Agricultural Research Service

Title: Scaling and Estimating the Soil Water Characteristic Using a One-Parameter Model.

Authors
item Williams, Robert
item Ahuja, Lajpat

Submitted to: CRC Press
Publication Type: Book / Chapter
Publication Acceptance Date: January 10, 2003
Publication Date: March 10, 2003
Citation: WILLIAMS, R.D., AHUJA, L.R. SCALING AND ESTIMATING THE SOIL WATER CHARACTERISTIC USING A ONE-PARAMETER MODEL. CRC PRESS, BOCA RATON, FL. SCALING METHODS IN SOIL PHYSICS. 2003. P. 35-40.

Interpretive Summary: Abstract Only.

Technical Abstract: A one-parameter model of the soil water retention curves is based on a strong, linear relationship observed between the intercept and slope of a log-log plot of the matric potential and the soil water content below the air-entry value. Furthermore, for widely different soils this relationship is found to coalesce into one common relationship. These characteristics allow representation of the soil water retention curve by a Brooks-Corey type function with only one unknown parameter, the slope of the log-log plot. Thus, the soil water retention curve for a variety of soils, and a range of textures, can be scaled based on their known slope value, or known -33 kPa water content from which the slope can be obtained. Here we derive a generalized relationship between the slope and intercept values on mean water retention curves for eleven textural classes. Using this generalized relationship with the one-parameter model, we scaled several groups of soils. The results show that this technique can effectively scale the soil water retention curves across heterogeneous, "non-similar media," soils. The inverse process of estimating a water retention curve from one known value, based implicitly on the scaling, is also demonstrated.

Last Modified: 11/23/2014