石羊河下游民勤绿洲地下水矿化度的时空变异

结合地理信息系统,运用地统计学方法研究石羊河下游民勤绿洲近15年来的地下水矿化度的时空变异规律及其与土地利用变化的关系。结果表明:(1)在1987年和2001年的两个时期地下水矿化度的实验变异函数值与理论变异函数拟合较好,F检验达到极显著水平;(2)地下水矿化度在4km以下小尺度上的随机变异SHR特别小,而在4～40km的中尺度上的结构性变异SHA达99.9%,可以认为研究区域内地下水矿化度在整个尺度上具有恒定的变异;(3)Kriging插值及其与同期的绿洲景观类型图进行叠加运算表明,在变化趋势上,除坝区东南部略有下降外,整个绿洲地下水矿化度都增大,北部湖区最显著;在变化面积上,地下水矿化度在3.0g/L以下的面积从1987年的75.26%降到了2001年的58.54%;而其>4.5g/L的绿洲主要集中在湖区。地下水矿化度较低区域的耕地面积减少,而地下水矿化度3.0g/L以上的耕地面积从7.03%增加到了14.32%,特别是湖区,地下水的矿化已严重威胁到了耕地的存在。

The Variability of Groundwater Mineralization in Minqin Oasis

Based on spatial analysis function of GIS, spatial heterogeneity of groundwater mineralization and its relationship with land use dynamics in Minqin oasis of Shiyang river watershed were studied using semivariogram and ordinary Kriging of geostatistics in this paper. Spherical model was fit for both data sets in 1987 and 2001, and the results of an F-test showed that the difference was significant. The spatial heterogeneity of groundwater mineralization caused by random factors was very small, and that caused by automatic factors accounted for 99.9%. Results of mapping of groundwater mineralization by Kriging and comparison with landscape maps in the same period show that: the area with groundwater mineralization lower than 3.0 g/L decreased from 75.26% in 1987 to 58.54% in 2001, and the area with groundwater mineralization greater than 4.5g/L is distributed in Huqu, northern part of Minqin oasis. Also, area of farmland with groundwater mineralization greater than 3.0 g/L increased from 7.03% in 1987 to 14.32% in 2001.