非饱和土壤统计特征对宏观弥散度影响的分析

An Analysis of Macrodispersivity for Adsorbing Solute Transport in Heterogeneous Unsaturated Soils

本文研究了重力为非饱和水分运动主要驱动力时,吸附溶质的宏观弥散度与孔隙介质统计特性和水力特性的关系,研究结果表明,宏观弥散度随溶质运移距离的增加而增加,并逐渐趋于一常数,宏观弥散度是土壤含水量、溶质吸附特性以及非饱和土体统计参数的函数,随平均含水量的增加而减少,随平均吸附因子和σ_f^2、σ_a^2λ_f和λ_a的增加而增大.当溶质运移距离很大时,宏观弥散度为非饱和渗透系数的方差和相关距离的线性函数.

The effect of the statistical properties and the hydraulic properties on the macrodispersivity is studied for the adsorbing solute transport in heterogeneous unsaturated soil. It is shown that the macrodisper-sivity increases with the incresing solute travel distance and tends to a constant. The macrodispersivity is a func-tion of mean water content , the adsorbing property, and the soil statstical properties. The macrodispersivity in-creases with the decreasing mean water content and increases with the increasing variances and correlation lengths of saturated conductivity and soil parameter α , and mean adsorbing factor. The macrodispersivity is a linear function of the variance and correlation length of the unsaturated hydraulic conductivity when the solute moves a long distance.