Study on Spaital Variability and Optimal Estimation of Unsaturated Flow Parameters

The data for soil hydraulic properties collected on a 30m×30m field with sandy loam soil has been investigated by the statistical method,the results show that the saturated hydraulic conductivity KS and soil water capacity are the normally distributed,and the pore size distribution parameter α is the log-normally distributed respectively.According to geostatistical method,the spatial stuctures of KS and lnα are characterized by the spherical semivariogram model.The Kriging technique is used for the spatial estimation of KS and lnα,the results indicate that the estimating variances are approximately the same as those when the sample points are reduced by 26 percent,and the average estimating variance of Cokriging method is about 6.87 percent lower than that of the Kriging method for parameter lnα.