Applicability of Fractal Models in Estimating Soil Water Retention Characteristics from Particle-Size Distribution Data

Soil water retention characteristics are the key information required in hydrological modeling. Fractal models provide a practical alternative for indirectly estimating soil water retention characteristics from particle-size distribution data. Predictive capabilities of three fractal models, i.e., Tyler-Wheatcraft model, Rieu-Sposito model, and Brooks-Corey model, were fully evaluated in this work using experimental data from an international database and literature. Particle-size distribution data were firstly interpolated into 20 classes using a van Genuchten-type equation. Fractal dimensions of the tortuous pore wall and the pore surface were then calculated from the detailed particle-size distribution and incorporated as a parameter in fractal water retention models. Comparisons between measured and model-estimated water retention characteristics indicated that these three models were applicable to relatively different soil textures and pressure head ranges. Tyler-Wheatcraft and Brooks-Corey models l