Use of X-ray CT scan to characterize the evolution of the hydraulic properties of a soil under drainage conditions

Characterization of soil hydraulic properties is essential for modelling water flow and solute transport in the vadose zone. These properties are often assessed assuming that the soil is a non-deformable (rigid) porous medium. However, under real conditions, such as those found in agricultural systems, the soil is constantly exposed to external stresses induced by farm machinery and by wetting and drying cycles, which constantly modify the soil hydraulic properties. The main objective of this work was to develop a methodological framework based on X-ray CT scanning to predict the spatio-temporal evolution of the hydraulic properties of a soil under drainage conditions. The methodological framework combines the particle size distribution of a soil and the fractal dimension of its porosity obtained from X-ray CT scans to predict the saturated hydraulic conductivity and volumetric deformation of a soil column. The results show that the proposed framework provides a realistic description of the spatio-temporal evolution of the hydraulic properties of a soil during the drainage process.