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An Alert Regarding a Common Misinterpretation of the Van Genuchten α Parameter

Quirijn de Jong van Lier, Everton Alves Rodrigues Pinheiro

18/Jun/2018

DOI: 10.1590/18069657rbcs20170343

ABSTRACT

Among the equations available to describe the relation between matric potential and soil water content, the soil water retention function, the most commonly used is the equation proposed by Van Genuchten in his 1980 landmark paper. In soil physics literature, especially in Brazil, several authors relate the inverse of the Van Genuchten parameter α to the air-entry pressure. This study aimed to show this common interpretation to be erroneous, as 1/α corresponds to water contents lower than saturation. The deviation depends on the m parameter. In fact, α is merely a scaling parameter relative to the matric potential axis. Recognizing this mathematical fact may improve the interpretation of soil hydraulic properties based on water retention parameters.

An Alert Regarding a Common Misinterpretation of the Van Genuchten α Parameter

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