Estimation of the van Genuchten Soil Water Retention Properties from Soil Textural Data  

作　　者：B. GHANBARIAN-ALAVIJEH A. LIAGHAT HUANG Guan-Hua M. Th. VAN GENUCHTEN 

机构地区：[1]Department of Irrigation and Reclamation Engineering, University of Tehran, Karaj 31587-77871 （Iran） [2]Department of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435 （USA） [3]Department of Irrigation and Drainage Engineering, China Agricultural University, Beijing 100083 （China） [4]Department of Mechanical Engineering, Federal University of Rio de Janeiro, RJ 21945-970 （Brazil）

出　　处：《Pedosphere》2010年第4期456-465,共10页土壤圈（英文版）

基　　金：Supported by the National Natural Science Foundation of China (Nos.50979106 and 50779067)

摘　　要：The van Genuchten (vG) function is often used to describe the soil water retention curve (SWRC) of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model parameter m from the fractal dimension. We compared two approaches previously proposed by van Genuchten and Lenhard et al. for estimating m from the pore size distribution index of the Brooks and Corey (BC) model. In both approaches we used a relationship between the pore size distribution index of the BC model and the fractal dimension of the SWRC. A dataset containing 75 samples from the UNSODA unsaturated soil hydraulic database was used to evaluate the two approaches. The statistical parameters showed that the approach by Lenhard et al. provided better estimates of the parameter m. Another dataset containing 72 samples from the literature was used to validate Lenhard's approach in which the SWRC fractal dimension was estimated from the clay content. The estimated SWRC of the second dataset was compared with those obtained with the Rosetta model using sand, silt, and clay contents. Root mean square error values of the proposed fractal approach and Rosetta were 0.081 and 0.136, respectively, indicating that the proposed fractal approach performed better than the Rosetta model.The van Genuchten （vG） function is often used to describe the soil water retention curve （SWRC） of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model parameter m from the fractal dimension. We compared two approaches previously proposed by van Genuchten and Lenhard et al. for estimating m from the pore size distribution index of the Brooks and Corey （BC） model. In both approaches we used a relationship between the pore size distribution index of the BC model and the fractal dimension of the SWRC. A dataset containing 75 samples from the UNSODA unsaturated soil hydraulic database was used to evaluate the two approaches. The statistical parameters showed that the approach by Lenhard et al. provided better estimates of the parameter m. Another dataset containing 72 samples from the literature was used to validate Lenhard＇s approach in which the SWRC fractal dimension was estimated from the clay content. The estimated SWRC of the second dataset was compared with those obtained with the Rosetta model using sand, silt, and clay contents. Root mean square error values of the proposed fractal approach and Rosetta were 0.081 and 0.136, respectively, indicating that the proposed fractal approach performed better than the Rosetta model.

关 键 词：fractal dimension soil water retention curve van Genuchten parameterization 

分 类 号：S152[农业科学—土壤学]