土壤热特性参数空间变异性与拟合方法研究

采用3S技术相结合的方法,在陕西省泾惠渠灌区研究了土壤热特性参数区域尺度的空间变异性,结果表明:土壤热容量、热扩散率及土壤导热率在该区域尺度下属于中等变异,土壤热扩散率和导热率的空间异质性较强,而土壤热容量的空间异质性相对土壤热扩散率和导热率表现较弱,三者均具有较强的空间依赖性。土壤热容量、热扩散率及土壤导热率的最优拟合模型分别为指数、球型、高斯模型,推荐三者的采样间距分别为2.67、3.68、2.76 km,推荐该区域范围内土壤热特性参数空间变异采样间距的最优值为3 km。在描述土壤热特性参数空间变异特征的基础上,建立利用土壤物理基本参数拟合土壤热特性参数的简单公式,并验证了此方法的适用性,决定系数R2达0.80以上,利用此方法能够实现土壤热特性参数的空间变异特征在复杂程度上的定量化。

Spatial Variability of Soil Thermal Parameters and Its Fitting Method

There are some research difficulties and highlights in analyzing spatial variation in recent years, such as how to choose advanced methods, how to make efficient and reasonable experimental designs, how to normalize field sampling program process, and how to select representative sampling points. In view of the above mentioned issues, a research on spatial variable of soil thermal parameters on basin scale in Jinghui Canal Irrigation District, Shaanxi Province was conducted by combining RS, GPS and GIS technology. The results showed that soil thermal capacity, thermal diffusion and thermal conductivity displayed moderate variation in the selected regional scale. Thermal diffusion and thermal conductivity displayed a stronger spatial heterogeneity than soil thermal capacity, which showed a relative weaker one. Furthermore, a strong spatial dependence was found among the above three parameters. The optimum fitting models for soil thermal capacity, thermal diffusion and thermal conductivity were exponential model, spherical model and Gaussian model, respectively. And the sample spacings of above three models were recommended to be 2.67, 3.68 and 2.76km, respectively. Meanwhile, the best sampling spacing of soil thermal parameters in this region was recommended to be 3km. A simple fitting formula for soil thermal parameters determined by basic parameters of soil physics was established based on describing the spatial variability of soil thermal parameters. It was proved to be a good applicability with R2>0.80 after verifying. It indicated that quantization analysis on complex spatial variability of soil thermal parameters could be well achieved based on the introduced method.