天山北麓地下水与自然植被的空间变异及其分形特征

对面积约670km^2的具有干旱气候特征的新疆三工河流域地下水埋深和自然植被盖度进行取样检测，应用地质统计学方法对取得数据进行半方差函数分析，计算均值、方差、标准差、变异系数等传统统计特征值，指出用该方法表示地下水埋深和自然植被盖度引起的困惑。在此基础上，将分形理论与地质统计学原理相结合，计算了三工河流域地下水埋深和自然植被盖度的分形维数，分别为1．3154、1．3677；而它们的变异系数分别为0．．537、0．368。该地区地下水埋深和自然植被盖度在空间上存在显著的变异性，而且它们具有相似的变异特征，即随着地下水埋深的递增(或递减)，自然植被盖度有所减少(或增加)，说明干旱区自然植被盖度对地下水埋深有很大的依赖性。这暗示着在干旱地区影响自然植被盖度的众多因素中最具有决定性的因素是地下水埋深。

Spatial Variability and Fractal Dimensions of Groundwater and Natural Vegetation in the North Foot of Tianshan Mountain

Sampling and testing are conducted on the groundwater depth and natural vegetation cover in the 670 km~2 of Sangong River Basin and semi-variance function analysis is made afterwards on the data obtained by the application of geo-statistics, and the statistical properties that mean, variance, standard deviation, coefficient of variance were analyzed with both traditional and geological statistical methods. Some difficulties were met with the traditional statistical technique. Combined with fractal theory, the fractal dimensions of groundwater depth and natural vegetation cover were determined, being 1.315 4,1.367 7, while their coefficients of variance were 0.537,0.368 respectively in 2003. Results from studying and examining showed that the groundwater depth and natural vegetation cover were not a medium with theoretical fractal phenomenon, and the fractal features only existed in the range of specific space in arid land. Analyses of sampling from 2003 indicate that the groundwater depth and natural vegetation cover vary spatially in this area, and they showed similar variability mutually. The natural vegetation cover is decreasing while the groundwater level is descending, this indicate that the groundwater depth is the crucial factor in the most of other factors which impact on variation of natural vegetation cover.