Spatial variability of soil properties

通过最小化实测值与换算值的平方和，建立了确定基质吸力、非饱和导水率和土壤水分扩散率换算系数的方法。两种方法被用来确定的缩放系数;从实验方程的有效饱和度的函数和测量值的平均值的估计被用作规模减少的值。标度效应在任何情况下都是显著的，两种方法得到的标度系数值相似。不使用实验方程时的平方和小于使用实验方程时的平方和。结果表明，前者是非常有用的，因为缩放是很容易做到的-不同的属性，只需改变的值的系数在约化变量kriging技术建立，以估计未知值从有限数量的测量值。该程序包括以下三个步骤。首先，半变异函数被确定为滞后距离的线性方程。其次，通过最小化估计误差来确定最优邻域大小。最后，从最佳邻域大小内的测量值估计任意点处的值。绘制了沙丘砂和围海造地土壤颗粒组成、土壤溶液离子浓度、土壤盐分和溶液pH的等值线图。用克里金估计绘制的等值线图比仅用实测值绘制的等值线图清晰得多。利用分布相似的两个性质之间的线性预测方程，可以从一个性质的值估计另一个性质的值。

A technique for determining the scaling coefficients for matric suction, unsaturated hydraulic conductivity and soil water diffusivity was established by minimizing a sum of squares between the measured values and the scale reduced values. Two methods were used in determining the scaling coefficients; the estimates from an experimental equation as the function of the effective saturation and the average of the measured values were used as the scale reduced values. Scaling effect was noticeable for any case and the similar values of scaling coefficients were obtained for the two methods. The sum of squares was smaller in the case that the experimental equation was not used than that the equation was used. It was concluded that the former was very useful because scaling is easily done-for the different properties only by changing the value of coefficients in the reduced variables.The kriging technique was established in order to estimate the unknown values from the limited number of measured values. The procedure includes the following three steps. First, a semi-variogram is determined as the linear equation of the lag distance. Next, the optimum neighborhood size is determined by minimizing the estimate error. Finally, the value at the arbitrary point is estimated from the measured values within the optimum neighborhood size. The contour maps were made for particle size fraction, ion concentration in the soil solution, soil salinity and solution pH in dune sand and reclaimed land from sea. The contour maps drawn by kriging estimates were far clearer than those drawn only by the measured values. The values of one properry could be estimated from those of another property by using the linear predictive equation between two properties with the similar distribution.