Estimation of Soil Water Retention Curve: An Asymmetrical Pore-Solid Fractal Model  

作　　者：WANG Kang ZHANG Renduo 

机构地区：[1]State Key Laboratory of Water Resources and HydropowerEngineering Science, Wuhan University, Wuhan 430072, Hubei, China [2]School of Environmental Science and Engineering, Sun Yat-SenUniversity, Guangzhou 510275, Guangdong, China

出　　处：《Wuhan University Journal of Natural Sciences》2011年第2期171-178,共8页武汉大学学报（自然科学英文版）

基　　金：Supported by the National Basic Research Program of China (973 Program) (2010CB951102);the National Natural Science Foundation of China (51039007, 50979076);the Open Research Fund of Key Laboratory for Water Requirement and Regulation, Ministry of Agriculture (CWRR200901)

摘　　要：The soil water retention curve is an important hydraulic function for the study of flow transport processes in unsaturated soils. The objective of this study was to develop a soil water retention function using a generalized fractal approach. The model exhibits asymmetry between the solid phase and pore phase, which is in marked contrast to the symmetry between phases present in a conventional fractal model. The retention function includes 4 parameters： the saturated water content θs, the air entry value ha, the fractal dimension Df, and an empirical parameter β, characterizing the complicated soil pore structures. Sixty one data sets, covering a wide range of soil structure and textural properties, were used to evaluate the applicability of the proposed soil water retention function. The retention function is shown to be a general model, which incorporates several existing retention models. The values of β/θs and （θs-θr ）/β were used as indexes to quantify the relationships between the proposed retention function and the existing retention models. The proposed function fits all the data very well, whereas other tested models only match about 16%-48% of the soil retention data.The soil water retention curve is an important hydraulic function for the study of flow transport processes in unsaturated soils. The objective of this study was to develop a soil water retention function using a generalized fractal approach. The model exhibits asymmetry between the solid phase and pore phase, which is in marked contrast to the symmetry between phases present in a conventional fractal model. The retention function includes 4 parameters： the saturated water content θs, the air entry value ha, the fractal dimension Df, and an empirical parameter β, characterizing the complicated soil pore structures. Sixty one data sets, covering a wide range of soil structure and textural properties, were used to evaluate the applicability of the proposed soil water retention function. The retention function is shown to be a general model, which incorporates several existing retention models. The values of β/θs and （θs-θr ）/β were used as indexes to quantify the relationships between the proposed retention function and the existing retention models. The proposed function fits all the data very well, whereas other tested models only match about 16%-48% of the soil retention data.

关 键 词：soil water retention curve FRACTAL pore-solid structure soil physical and hydraulic properties asymmetry 

分 类 号：S152.7[农业科学—土壤学] TP391.41[农业科学—农业基础科学]