Preliminary Study On Space Variability Of Water-Salt And Robust Variogram

On the basis of requirements on water-salt monitoring and evaluation in zone water environment forecasting, this paper studies the Time-Space Variability of Water-Salt and the Robust Variogram. in order to replant theory and methods of Robust Geostatistics into Water-Soil science, and remedy the lack of the traditional Geostatistics, utilizing water-salt spring sampling data from two experiment section in Hetao irrigation zone, analyzes sutra statistical identity of the sampling data and sampling scale, calculates traditional Geostatistics Variogram, analyzes disturbance of outliers, then stab calculating the Robust Variogram after eliminating the outliers, while directly calculates two kinds of Robust Variogram, analyzes the traditional Geostatistics and three kind of Robust Variogram by comparing them, conclusions as follows(1)the water-salt sampling data almost attribute departure distribution,disturbance of the outliers is a main factor.(2)effect on experimental Variogram in different scales is different,we should select suitable scale to calculate.(3)because of the disturbance of the outliers,it affects Robustness of the Variogram and spatial structures of regional variables,so it is very essential to eliminate the outliers for calculating water-salt spatial Variogram.(4)the method of robust estimating can improve effect of the Variogram statistic character,three kinds of robust estimating methodes in this paper are distinctly superior to the traditional Geostatistics experimental Variogram, consists of the effective modulus method, location Huber estimating and Cressie.Hawkins method, among them, the effective modulus method is obviously superior to the others. Comparing academic Variogram by simulating using the three methods and that from raw data, we can find obviously rules: gold nugget constant C0 debases obviously, randomiciry of the regional variables minishes, statistical value minishes greatly, showing that simulating effect become better;C0+C minshes, it show that changing extent of the variable on this aspect debases; curves of the Robust Variogram have trend that C/C0 minish disparately, variance become small, changing area "a" changes not too, all show that the former from the Robust estimating is more trusty. Kriging gaging former plots and classic isoline maps of two vertical direction combination structure model reflect actual water-salt content. The maps offer basal ' estimating basis for accumulating many years of Water-salt dynamic forecasting. (5) the Robust estimating has advantages of credible result and that control balance between Robustness and ensuring information quantity. (6)via calculating and analyzing, we cansay that the Robust Geostatistics methods can be introduced into the Water-Soil science, this has very important appliance and learning merit for enhancing studying on the Water-Salt spatial variability along with basal studying on the Robust Variogram.