Effects of Constraints on van Genuchten Parameters for Modeling Soil-Water Characteristic Curves
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 140, Issue 12
Abstract
Water-retention data for a suite of predominantly sandy soils were analyzed to quantify the effects of two constraints commonly applied to the three-parameter model for the soil-water characteristic curve (SWCC). Systematic effects were observed. Constraining either the symmetry parameter () to or residual saturation () to zero resulted in values for the air-entry parameter that were approximately 25–30% different than if no constraints were applied. The constraint forced the pore-size distribution parameter to fall within a narrow range (), whereas values using independent and were more variable and could be as large as 35. The constraint produced best-fit residual saturation values that were approximately 0.02 higher than without the constraint. These differences are significant and should be considered when adopting existing or new pedotransfer functions for estimating water-retention behavior of unsaturated soils from more easily measured properties.
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Acknowledgments
This material is based on work supported by the National Science Foundation (NSF) under Grant 1304139. Any opinions, findings, conclusions, and/or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 140 • Issue 12 • December 2014
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© 2014 American Society of Civil Engineers.
History
Received: Apr 2, 2014
Accepted: Jul 1, 2014
Published online: Jul 30, 2014
Published in print: Dec 1, 2014
Discussion open until: Dec 30, 2014
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