苏北海涂围垦区土壤水分空间变异性及其协同克立格估值

以苏北滨海滩涂围垦区为研究区域,应用地统计学方法研究了剖面不同深度土壤含水量的空间变异特征,以0～20 cm表土层含水量作为协同变量,分析了不同深度土壤含水量的交互半方差特征,探讨了土壤含水量的普通克立格和协同克立格估值方法.结果表明:各层土壤含水量都表现为弱变异强度;受结构性因素和随机性因素的共同作用,各土层含水量均呈中等空间自相关性;协同区域化变量间均表现为正相关,且协同区域化变量的空间结构性要优于单一变量;协同克立格对土壤水分局部变异的描述较普通克立格更为详细;与普通克立格法相比,协同克立格法估值产生的均方误差减小10.1%～21.3%,平均标准误差减小11.3%～17.7%,预测值和实测值间的相关系数提高15.9%～26.4%.该研究为滨海滩涂地区土壤水分分区管理和水盐优化调控提供了一定的理论参考.

Spatial Variability of Soil Moisture and Its Estimation by CoKriging Method in Coastal Region of North Jiangsu Province

Spatial variability of soil moisture at different layers in the coastal region of north Jiangsu Province was studied by using geostatistics in this paper. Cross-semivariogram was then used to analyze the coregionalized relationship between surface soil moisture and moisture at deep soil layers, and estimation of soil moisture by Kriging and CoKriging was discussed. Results indicated that soil moisture exhibited weak variation and moderate spatial autocorrelation owing to compound impact of structural and stochastic factors. Coregionalized variables both showed positive correlation and the spatial structure of coregionalized variables was superior to that of univariable. Short-range variability of soil moisture was depicted more detailedly by CoKriging than ordinary Kriging. Compared with ordinary Kriging method, the root-mean-square error produced by CoKriging decreased by 10.1% to 21.3%, the average standard error decreased by 11.3% to 17.7%, and the determination coefficient between the observed values and the predicted values increased by 15.9% to 26.4%. The research results can serve as a theoretical reference to the regional management of soil moisture and optimal regulation of soil water and salt in coastal region.