塔里木河源流区绿洲土壤含盐量空间变异和格局分析——以岳普湖绿洲为例

基于区域变量理论,在GPS和GIS技术支持下,通过地统计学的半变异函数和Kriging空间插值,以岳普湖绿洲为例,定量分析塔里木河源流区绿洲不同层次土壤盐分的空间异质性。结果表明:0~30cm、30~60cm和60~100cm土壤盐分半方差函数的理论分布模型属于指数模型,100~200cm属于球状模型。不同土层之间的空间自相关范围具有明显的差异,由表层至深层,土壤盐分的自相关范围逐渐增大。土壤盐分的空间格局分析表明,在水平方向上,研究区各层土壤盐分的高值区主要集中分布在人类活动强烈、靠近河渠水源和地势较为低洼区域;在垂直方向上,土壤表层盐分含量最高,向深层逐渐减少。

Study on spatial variability and pattern of soil salinity of the oasis in the headstreams of the Tarim River Basin:A case study on Yuepuhu oasis

Soil properties are one of the regional variables with the properties of geological structure and the stochastics of statistics.Geostatistics,based on the regional variable theory,has been proved to be one of the most effective methods to analyze the spatial distribution and its variation law of soil properties.It is the foundation to well manage the soil and prevent the soil salinization for fully understanding the spatial distribution of soil salinity.In the present study,based on regionalized variable theory,the spatial variability of soil salinity in different soil layers were studied by means of GPS,GIS,semivariograms of geostatistics and Kriging method in Yuepuhu oasis to quantificationally analyze the spatial variation and patterns of soil salinity in the headstream area of the Tarim River,with the purpose of provideing the academic basis for the area partitioning,meliorating and utilizing salinized soil in arid oasis.In the study,118 samples were chosen from four soil layers at depths of 0-30cm,30-60cm,60-100cm and 100-200cm.The results indicated that the salt contents in different soil layers were high with 17.44g/kg,11.67g/kg,9.10g/kg and 8.14g/kg in 0-30cm,30-60cm,60-100cm and 100-200cm,respectively.The semivariogram of soil salinity of the four depths was best described by the Exponential model,of which the 100-200cm layer was best fitted by the Spherical model.The ranges of spatial autocorrelation differ from each other among the different soil layers.From the surface to the deeper layer,the autocorrelation ranges of the soil salinity increased gradually with 56.40 km,91.10 km,114.10 km and 160.00 km,respectively.The analysis of spatial pattern of soil salinity indicated that high values of soil salinity were mainly distributed at the places that were under the intensive anthropogenic activities,near to the watershed or located at low-lying areas.In vertical direction,the salinity of surface soil was the highest and it decreased gradually with the increase of soil depth.In the study area,the spatial variations and patterns of soil salinity in oasis were restricted to both the structural factors and the non-structural factors.For the impact of structural factors on surface soil was relatively less,and that of non-structural factors,i.e.anthropogenic activities,was greater.Some structural factors,such as topography,soil matrix,superficial groundwater table and soil water content from headstreams,strengthened with the increase of soil depths,and the spatial variations of soil salinity increased.