Study On Calculation And Spatial Variability Of Soil Hydraulic Properties

This thesis was supported financially by a NSFC project, titled "Scale-Dependency and Spatial Variability of Soil Hydraulic Properties". The disc infiltrometer is becoming a useful device for in-situ measurements of soil hydraulic properties in the field. Several methods have been developed to calculate hydraulic properties based on infiltration data under the disc infiltrometer. However, these methods exist some limitations. In this study, a new method was developed by considering the influence of gravity for large disc infiltrometers. Extensive numerical simulated and experimental data were used to examine the proposed method for various soils and different radii and tensions of the disc infiltrometer. Base on infiltration data under disc infiltrometers, the proposed method and other methods in the literature were utilized to calculate soil hydraulic conductivity and macroscopic capillary length. Compared with the other methods, the proposed method provided more accurate and stable estimations of the hydraulic properties, especially for using large disc infiltrometers. In addition, a field experiment was conducted to measure infiltration processes at 100 locations using the disc infiltrometer. Spatial variabilities of soil hydraulic properties were analyzed using the field data and geostatistal methods.