内陆河灌区土壤水分空间变异的尺度效应

Scale effect of spatial variability of soil water content in inland irrigation areas

采用经典统计学和地统计学Kriging插值法研究了内陆河灌区土壤水分空间变异的尺度效应．结果表明,尺度对经典统计学参数中的中值和平均值的影响很小,对方差和变异系数的影响较大．在垂直剖面上,不同水平层次土壤含水量的方差和变异系数的变化规律随尺度而不同．土壤水分的等值线在垂直剖面上的分布规律在相同的尺度下是不同的,并且与经典统计学参数所反映的垂直变化规律也不相同,但相邻层次上具有相似性．在尺度变化的情况下,随着尺度的变大,土壤水分的等值线变得越来越稀疏,闭合中心的数量逐渐减少,位置发生移动．说明土壤水分空间变异性与采样点数目和采样尺度密切相关,随着采样尺度的增加,土壤性质的结构等级发生转变,不同结构性等级中,影响土壤水分的过程、因素不同．

Scale effect of spatial variability of soil water in inland irrigation areas was studied with traditional statistics and Geo-statistics. The results showed that the scale took little influence on mean and media of parameters in traditional statistics, but had a great effect on variance and CV. On the vertical section,the changes of variance and CV in different soil layers were different along with the scale,Moreover, the changing pattern of isogram of soil water was different under the same scale and was alsodifferent from the changing pattern of variance and CV from the traditional statistics. However, changing pattern of isogram of soil water content were similar between near layers along vertical section. While, isogram of soil water content became more sparse, the number of closed center of isogram decreased and the location of closed center of isogram moved with changing of scale. That illustrated that spatial variability of soil water could related closely to sample number of soil and sampling scale, soil water structural grade changed with the increasing of sampling scale, and the different soil water structural grade had different factors and processes which effected the soil water.