非饱和水流动态空间变异的随机分析

Stochastic analysis of spatial variability for variables of unsaturated flow

本研究首先根据野外３０ｍ×３０ｍ的小区域上以一定的间距布设１００个土壤张力监测网点，对土壤张力在空间和时间上变化进行了观测，并对土壤张力的空间变异结构进行了随机统计分析．然后以野外实测的土壤水力特性参数样本的统计分析结果为基础，在假设有关土壤水力特性参数及非饱和水分运动变量为二阶平稳随机场的条件下，应用小扰动分析法导出了层状土壤非饱和水流变量（张力）方差的解析结构．理论分析和试验结果同时表明，土壤张力的方差随张力均值的增大而增大，且方差是均值的二次函数，同时土壤张力的变差函数也是土壤张力平均值的二次函数．

The data of tension head collected from field site have been analyzed with statistical method. The result shows that the spatial structure of capillary tension head can be characterized by linear semivariogram model with the mean of capillary tension head as its variable. According to the statistical distributions from experimental data the analytical expressions of capillary tension head are derived with small perturbation method. Both experimental data and analytical expression indicate that variance of capillary tension head is a quadratic function and increases with its means. The comparison of analytical variance against the experimental data indicates that the analytical result is larger than the experimental result.