根据土壤水分特征曲线推求土壤的导水参数

PREDICTING THE HYDRAULIC CONDUCTIVITY AND WATER DIFFUSIVITY OF UNSATURATED SOILS FROM THE SOIL WATER CHARAGTERISTIG CURVES

本文中描述了土壤水分特征曲线的一个相对简单的幂函数方程。当把这一方程代入Burdine或Mualem的预报土壤导水率的模式后,可以得到相对导水率的分析解。相对导水率的表达式中仅包含一个参数,该参数用实验资料拟合水分特征曲线模型而得到。并结合特征曲线方程,给出了土壤水分扩散率的表达式。从Burdine和Mualem模式获得分析解的结果,与具有较宽范围导水性质的四种土壤的导水参数实测资料进行了比较。非饱和土壤导水率的预报结果良好;土壤水分扩散率的预报结果对其中三种土壤良好。

A relatively simple equation for the soil-water charateristic curve, power function, is described in this paper. The particular form of the equation enables one to derive analytical expressions for the relative hydraulic conductivity, when substituted in the predictive conductivity models of Burdine or Mualem. The resulting expression for fhe conductivity contains only one independent parameter which can be obtained by fitting the proposed soil water characteristic model to experimental data. With the soil water characteristic curve, the expression of soil water diffusivity is also given in this paper. Results obtained with the analytical expressions based on Burdine and Mualem models are compared with measured hydraulic conductivity and water diffusivity data for four soils with a wide range of hydraulic properties. The unsaturated hydraulic conductivity is predicted well in all cases and the water diffusivity is predicted well in three out of four soils.