Spatial Variability Characteristics Analysis And Mapping Technology Of Saline Soil In Yanqi Basin, Xinjiang

Aims: This research take the soil salinity in Yanqi Basin of Xinjiang as the study content, and it try to discuss the Spacial Variability characteristics of soil salinity in valley scale.Methods: In this paper, we use Geostatistics to analyse special variability of soil salinity in Yanqi Basin of Xinjiang base on soil salinity data, and then we predict and draw the soil-salinity-class maps including unsampled region, it shows to us: (1) the soil salinity data's Cv value are not less than 100% and have very strong special variability; (2)Analysing the salinity data by GS+ software, we found that the spherical model for Semi-variogram of soil salinity is perfect to the data and the soil salinity data have strong spatial correlation; (3) After we finished the Kriging map of salt in three soil layer respectively, we found that whether salinity content in soil heavy or not is correlative with terrain in Yanqi Basin, the non-salt-type soil area and light-salt-type soil area are mainly distributed in Kaidu river, Huangshuigou and Qingshui river irrigation & drainage region, while heavy-salt type soil and salt type soil are mainly distributed in the oriental and north region of Boseteng Lake; (4)Comparing with the three Kriging maps of salt, we estimated the soil have inverted salinity profiles by analyzing the areas of every type of salinity soil. From the 0-30cm to 60-100cm soil layer, the proportions about the areas of non-salt type soil and light-salt type soil occupying the research area increases from 9.4% and 37.0% to 45.4% and 43.9% respectively, while the proportions about the areas of middle-salt type soil, heavy-salt type soil and salt type soil occupying the research area declines from 22.1%, 22.1% and 4.1% to 10.4%, 0.3% and 0.0% respectively.Comparing with the salinity maps in Heshuo study region, which by processing ASTER DATA and by Geostatistics method respectively, we found: (1) the classification result using supervised classification method is obviously closer to the actual situation than the result using unsupervised classification method; (2) comparing with the proportions of the areas occupying the research area about by RS processing method and Geostatistics method, we found the proportion of non-salt type soil is 15.2% and 3.10% respectively, the proportion of salt type soil is34.1% and 25.9% respectively, the area non-salt type and salt type from RS processing method is greater than the area from Geostatistics method; while the proportion of light-salt type soil is 12.2% and 20.0% respectively, the proportion of heavy-salt type soil is 10.30% and 23.1% respectively, the area of light-salt type and heavy-salt type from RS processing method is lesser than the area from Geostatistics method. We found the area of middle-salt is nearly equal. From these data, we can say that the result about soil-salinity-class from RS processing method and Geostatistics method is obvious difference.At the same time, we analysed others ion such as SO₄^2-,Cl^-, CO₃^2-+HCO₃^-,Ca²⁺, Mg²⁺ and Na⁺+K⁺ in soil by using Geostatistics method, we found: (1) the Cv values of most ions are not less than 100% and the ion data have very strong special variability; (2) Analysing the salinity data by GS+ software, we found that the spherical model for Semi-variogram of the most ions are perfect to the data and the ions characteristic data have strong spatial correlation; (3) From the Kriging maps of SO₄^2-,Cl^-,Ca²⁺,Mg²⁺ and Na⁺+K⁺ in three soil layers, we can conclude the light-type soil area are mainly distributed in Kaidu river, Huangshuigou and Qingshui river irrigation & drainage region, heavy-type soil are mainly distributed in the oriental and north region of Boseteng Lake, but the distributed areas of CO32- +HCO3- is reversed to the distributed areas of SO₄^2-,Cl^-,Ca²⁺,Mg²⁺ and Na⁺+K⁺.Important findings: From this research we would get lots of scientific help about soil salinity treatment & improvement , agriculture planning & adjusting, and irrigation and drainage engineering planning in the future.