水蚀风蚀交错带土壤剖面水力学性质变异

土壤剖面水力学性质的确定是土壤水分动态预测的基础。该文在水蚀风蚀交错区六道沟流域分别对居于坡中和坡上两块样地160 cm土层不同深度未扰动土壤的水分特征曲线进行了测定，将Van Genuchtens水分特征曲线模式与Mualem导水模式相结合，确定了两样地土壤剖面的水力学参数，对水力学参数在剖面的变化进行了分析。结果表明，土壤剖面饱和含水率、滞留含水率、进气吸力倒数和孔隙大小分布因子沿剖面变化不大，滞留含水率、进气吸力倒数属于中等程度变异，饱和含水率和孔隙大小分布指标属于弱变异，但经方差检验均不显著，说明该地区160 cm土壤剖面可以处理成均质剖面。

Variation of the hydraulic characteristics of soil profile in water-wind erosion crisscross region

Hydraulic properties of the soil profile are the precondition to accurately predict the soil moisture dynamic distribution. In this study carried out in Liu Daogou watershed in water-wind erosion crisscross region, the undisturbed soil water retention curves of the different layers of two soil profiles located at the middle and upper part of a slope were firstly measured by centrifugal method, and then the soil hydraulic parameters such as saturated water content, residual water content, the inverse of the air-entry value and a pore-size distribution index were obtained by fitting soil water retention curve to the Van Genuchten soil water retention model connected with Mualem hydraulic conductivity model. By comparison among soil hydraulic parameters of the different layers, the changes of soil hydraulic parameters in the profile were analyzed. The result shows that the four parameters change weakly along the soil profile. According to the coefficient variation of four parameters, both of residual water content and the inverse of the air-entry value belong to weak variability, nevertheless the saturated water content and the pore-size distribution index belong to medium variability. However, all of the variations of the four parameters are not significant through variance test, which proves that the soil profile of 160 cm in depth in this region can be treated as the homogenous profile.