基于球状模型参数的地下水水位空间变异特性及其演化规律分析

根据宁夏青铜峡灌区169眼观测井的20世纪90年代逐月地下水埋深观测资料,应用地质统计学方法,结合GIS技术,研究了灌区地下水水位的空间变异特性在年际和年内的演变规律.地下水埋深样本呈对数正态分布,利用球状模型拟合变异函数,通过研究球状模型参数中短轴变程与长轴变程的比值,发现样本存在不同程度的几何各向异性,但逐年趋于各向同性;各向异性程度的年内变化与灌溉过程有关,地下水埋深越浅,其各向异性程度越强.球状模型参数中的块金值与基台值的比值反映地下水埋深样本具有中等的空间相关性,其大小与灌溉活动关系密切,地下水埋深越浅,空间相关性越大,反之亦然.克里金插值结果表明,灌区地下水埋深总体上逐年增加,在年内变化上,顺着地下水自南向北的流向,地下水位随灌溉呈周期性涨落变化.

Analysis on spatial and temporal variability of groundwater level based on spherical sampling model

Based on the monthly groundwater level data of 169 observation wells in the Qingtongxia Irrigation Area in 1990s, the geostatistics method and GIS technique are applied to analyze the intra annual and inter annual spatial temporal variability of the groundwater level. Spherical model is adopted to fit the log normal variogram of groundwater level distribution. The investigation on the ratio of minor range to major range of the model parameter reveals that the geometric anisotropy of sample distribution exists. But it tends to be isotropic year by year. The annual variation of anisotropic characteristics is closely related to the irrigation process. The higher the groundwater level, the more obvious inisotropic it will be. The result of Kriging interpolation shows that generally the groundwater level is gradually elevated year by year. While in the scale of year, in accordance with the flow direction of groundwater oriented from south to north, the groundwater level varies periodically with the irrigation operation.