A modification to the van Genuchten model for improved prediction of relative hydraulic conductivity of unsaturated soils

• Published in: European journal of soil science 2021-05, Vol.72 (3), p.1354-1372
• Main Authors: Kuang, Xingxing, Jiao, Jiu Jimmy, Shan, Jipeng, Yang, Zhenlei
• Format: Article
• Language: English
• Subjects: Constraint modelling; Data; Hydraulic conductivity; Hydraulic properties; Hydraulics; infiltration; Moisture content; relative hydraulic conductivity; Retention; Sandstone; Saturation; Sedimentary rocks; Soil; soil hydraulic properties; Soil properties; Soil texture; Soil water; soil water retention curve; Transport; Unsaturated flow; Unsaturated soils; Vadose water; van Genuchten model; Water
• ISSN: 1351-0754; 1365-2389
• DOI: 10.1111/ejss.13034

Modelling of flow and transport in unsaturated soils requires information on two fundamental hydraulic properties: the soil water retention curve and relative hydraulic conductivity. A soil's relative hydraulic conductivity is frequently predicted from the soil water retention curve. The most widely used combination is the van Genuchten model for the soil water retention curve and the Mualem model for relative hydraulic conductivity (VGM). Previous studies show that the VGM model underestimates measured relative hydraulic conductivity for soils with fine textures; a sharp drop in relative hydraulic conductivity can be seen near saturation. A new modification of the van Genuchten soil water retention model is proposed with the aim of improving the agreement between predicted and measured relative hydraulic conductivity. The Brooks and Corey‐Burdine model is used to predict relative hydraulic conductivity from the modified van Genuchten soil water retention curve (MVG‐BCB). The modified model assumes independent m and n in the van Genuchten model but with constraints n > 2 and 0