Geostatistical and fractal analyses of soil hydraulic properties

In this study several topics related to soil hydraulic properties were studied. First, the spatial variability of soil water retention and hydraulic conductivity functions was analyzed in two-dimensional and three-dimensional fields using geostatistics. The variability of soil hydraulic properties was closely related to the variability of soil physical properties, such as soil texture, structure, and bulk density. Moreover, the spatial variability of the soil hydraulic properties was dependent on the tillage systems applied in the studied area. Second, since measurements of the soil hydraulic properties are costly and time consuming, two methods were proposed for indirect estimation of the soil hydraulic properties based on the fractal theory and other more easily measured soil properties. The first method predicted soil water retention function using data of soil particle-size distribution, aggregate-size distribution and bulk density. The second method predicted soil water retention and hydraulic conductivity functions using soil particle-size distribution data. Reasonable agreement between experimental data and the predicted results was obtained for majority of the studied soils. Third, a soil water retention model was developed by applying the multifractal theory for characterizing soil porous media. Compared with experimental soil water retention data, the model provided relatively accurate estimations for the studied soils. All parameters of the proposed model possess certain physical meaning. Therefore, the parameter values can be estimated based on other soil properties and utilized for soil water retention predictions.