Brooks-Corey and van Genuchten Soil-Water-Retention Models

In 1989 Lenhard et al. discussed a method for converting van Genuchten's 1980 soil-water-retention model into a simpler power-law model of the form proposed by Brooks and Corey in 1964. In this paper, the effect of this conversion on the numerical modeling of infiltration in a variety of soil types is investigated. A simple modification to this conversion procedure, which matches hydraulic conductivities in the two models more closely, is also presented and tested. Both the original and the modified conversion procedure are more accurate for nonclayey soils (with a relatively narrow pore-size distribution) than for clayey soils. However, the difference in infiltration calculated using the van Genuchten and Brooks-Corey models is significantly reduced when the modified procedure is used.