基于数字图像的风蚀地表颗粒粒度特征及空间异质性

Grain size characteristics and spatial heterogeneity of wind erosion surface particles based on digital image

基于数字图像处理技术获取了吉兰泰盐湖北部风蚀粗粒化地表不同粒级风蚀颗粒的百分含量,并采用经典统计学和地统计学分析方法对各粒级颗粒的空间异质性进行了分析。结果表明:1)高度可蚀(<0.42mm)、半可蚀(0.42~0.84mm)和不可蚀(>0.84mm)颗粒百分含量的均值分别为17.20%、20.73%和47.38%,说明研究区地表物质组成以不可蚀颗粒为主。2)高度可蚀、半可蚀和不可蚀颗粒含量的变异系数分别为53.31%、32.75%和41.58%,3者的半方差函数最优拟合理论模型均为指数模型,变异系数和半方差函数模型说明地表物质组成中,颗粒越小,其空间分布的变异性越大。3)3类风蚀颗粒的空间分布格局均呈斑块状,说明颗粒空间分布格局是由结构因素和随机因素共同作用的结果。其中,成土母质、风蚀及植被分布状况是造成不同粒级颗粒分布出现差异的主要驱动力,此外,人为过程在一定程度上也影响了颗粒的再分布。

The coarse graining surface in the north of Jartai salt lake was selected as the research object. Based on the digital image processing technique, the percentage contents of different particle size of the wind erosion surface were obtained. The spatial heterogeneities of the particles of different size were analyzed through both classical statistics and geostatistics. The results showed that ： （ 1 ） The mean content of high - erodible, semi - erodible, non- erodible soil particles were 17.20%, 20.73% and 47.38%, respectively. It indicated that the surface materials in the study area are mainly composed of the non - erodible particles. （2） The variation coeffi- cient of the content of non - erodible, semi - erodible, high - erodible soil particles were 41.58%, 32.75% and 53.31%, respectively. The variation function model of optimal fitting theory of 3 types of particles were classi- fied as exponential model. Variation coefficient and variation function model indicated that the smaller the particle size, the larger the spatial variability. （3） All the 3 size particles were distributed as patches, which indicated that the spatial pattern of different types of wind erosion was the combined effect of structural factors and random factors. But the structural factors, such as the parent material, the distribution of wind erosion and vegetation in region, were the dominant driving forces of the spatial distribution of surface particles. In addition, artifi- cial process also affected the particle distribution to a certain extent.