摘要
Soil water retention characteristics are the key information required in hydrological modeling. Frac-tal models provide a practical alternative for indirectly estimating soil water retention characteristics fromparticle-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 datafrom an international database and literature. Particle-size distribution data were firstly interpolated into20 classes using a van Genuchten-type equation. Fractal dimensions of the tortuous pore wall and the poresurface were then calculated from the detailed particle-size distribution and incorporated as a parameter infractal water retention models. Comparisons between measured and model-estimated water retention cha-racteristics indicated that these three models were applicable to relatively different soil textures and pressurehead ranges. Tyler-Wheatcraft and Brooks-Corey models led to reasonable agreements for both coarse- andmedium-textured soils, while the latter showed applicability to a broader texture range. In contrast, Rieu-Sposito model was more suitable for fine-textured soils. Fractal models produced a better estimation of watercontents at low pressure heads than at high pressure heads.
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 led to reasonable agreements for both coarse- and medium-textured soils, while the latter showed applicability to a broader texture range. In contrast, Rieu-Sposito model was more suitable for fine-textured soils. Fractal models produced a better estimation of water contents at low pressure heads than at high pressure heads.
基金
Project supported by the National Natural Science Foundation of China (No, 49971041), the National Key Basic Research Support Foundation (NKBRSF) of China (No. G1999011803)
the Director Foundation of the Institute of Soil Science, CAS (No. ISSDF0004).
