基于Kriging和Cokriging方法的黄河三角洲土壤盐渍化评价

Evaluating the Spatial Distribution of Soil Salinity in the Yellow River Delta Based on Kriging and Cokriging Methods

土壤盐渍化是制约黄河三角洲农业可持续发展和生态系统良性循环的主要环境问题之一,掌握盐渍化土壤的空间分布规律对于因地制宜地制定盐渍土改良措施具有重要指导意义。本文在土壤盐渍化野外调查和对土壤样品含盐量实验分析的基础上,采用普通克里格和协同克里格两种方法对研究区土壤含盐量的空间分布情况进行了估算。结果表明,加入协变量的协同克里格模型可以普遍提高对含盐量估算的精度,而模型中主变量对各协变量的敏感度不一。从对含盐量计算精度提高的程度来说,各协变量依次为:Ph值>有机质>Cl-离子>高程值。通过插值得到的不同深度土壤含盐量分布图,为分析黄河三角洲土壤盐渍化的空间分布与变异特征,以及当地的盐渍化土壤治理和生态环境保护提供科学基础。

Soil salinity is one of the most urgent problems threatening the Yellow River Delta （YRD）. Understanding the spatial distribution patterns of saline soils is important to the sustainable development of agriculture and a healthy YRD ecosystem. Using soil samples collected in May 2006, we analyzed the chemical composition of soil and applied the Kriging and Cokriging methods to explore spatial autocorrelation among sampling points. We found that the Cokriging method generally improves accuracy when compared to the ordinary Kriging method. The sensitivity of the Cokriging model varied when covariables changed, the order of their influences was： pH value 〉 organic matter 〉 Cl^- ions 〉 elevation values. The spatial distribution and variation in soil salinity was concluded from final soil salinity maps generated using both methods. The salt content of top soil is generally higher than that of deep soil, and soil salinity increases from the Yellow River banks to coastline. Furthermore, the soil salinity of abundant YRD estuary is heavier than that of the new alluvial estuary. This research provides a scientific basis for the amelioration of soil salinity and protection of local environments in the YRD.