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结合地理信息系统 (GIS) ,利用地统计学方法研究了黄土丘陵沟壑区小流域土壤水分的空间结构特征及其季节变化规律。结果表明 :土壤水分具有较高的分维数 ,表现出强烈和中等程度的空间自相关。 1对平均土壤水分来说 ,基台值 (空间总变异 )的季节变化与其相反 ,在干旱季节 ,土壤水分的基台值高 ;湿润季节 ,基台值降低 ;而在极端干旱条件下 ,土壤含水量接近凋萎系数 ,土壤水分变异程度降低。变程的季节变化在干旱季节数值高 ,湿润季节变程小 ,且变程变化在 1 35～ 1 60 m之间。块金值 (随机变异 )变化在 0 .2和 1 .5,季节变化格局并不明显 ,与平均土壤含水量的季节变化具有某些相似性。2对剖面土壤水分来说 ,在整个观测期内 ,基台值 (不包括 5 cm土壤水分 )随剖面深度增加而增加。变程随土壤深度并不显示明显的趋势而呈现波动变化 ,其变化幅度 60～ 1 60 m,差异近 3倍。块金值随土壤深度也无明显格局 ,但其倾向于基台值高 ,块金值也高。土壤水分的空间结构特征及其季节变化能从土地利用、地形、降雨量和土壤物理性质等因子在不同季节影响土壤水分的相对作用大小得到解释
Combined with Geographic Information System (GIS), the geostatistics method was used to study the spatial structure and seasonal variation of soil moisture in the small watershed in the gully region of the Loess Plateau. The results showed that soil moisture had higher fractal dimension and exhibited strong and moderate spatial autocorrelation. 1 For the average soil moisture, the seasonal change of the abutment value (total space variation) is the opposite. In the dry season, the abutment value of soil moisture is high; in the wet season, the abutment value decreases; in extreme drought conditions, the soil Water content close to wilting coefficient, soil moisture variation decreased. The seasonal variation of the variability is high in the dry season and small in the wet season, with a variation in the range of 135-160 m. The nugget value (random variation) varies between 0.2 and 1.5, but the seasonal variation pattern is not obvious and has some similarities with the seasonal variation of average soil moisture content. 2 For profile soil moisture, abutment values (excluding 5 cm soil moisture) increased with profile depth throughout the observation period. Variations with the depth of the soil does not show a clear trend and showed fluctuations in the change range of 60 ~ 1 60 m, nearly 3 times the difference. The nugget value also has no obvious pattern with the soil depth, but it tends to have a high abutment value and high nugget value. The spatial structure of soil moisture and its seasonal variation can be explained by the relative effects of factors such as land use, topography, rainfall and soil physical properties on soil moisture in different seasons