近10a来民勤盆地地下水埋深的空间异质性分析

Spatial heterogeneity of Minqin Basin’s groundwater depth in recent 10 years

在GIS环境下,采用地统计空间分析技术,利用民勤盆地1999-2008年10 a的地下水位观测资料,在插值获取逐年地下水埋深栅格数据的基础上,对民勤盆地地下水埋深的时空格局和空间异质性进行了分析。结果表明:(1)1999-2008年民勤盆地地下水埋深急剧增大,整体平均每年增加幅度为0.52 m,地下水降落漏斗区逐年扩大,并有与附近漏斗区融合的趋势;(2)1999-2008年10 a间的地下水埋深的空间相关性逐年增大,表明民勤盆地地下水埋深的空间结构性逐年增强,地下水储存的空间连通性增加,地下水位的可恢复性和持续可开采性更为脆弱,影响地下水埋深的随机性因素逐渐下降,而人类活动对地下水埋深的影响越来越强烈。

Miqnin Basin is located in Gansu Province,northwest China where has the sharpest conflict of using water.Its total area is 5.2×103 km2,but the area of the oasis is just 1.5×103 km2 and is gradually reduced due to the shortage of water resources. Along with the population growth and the economic development,,groundwater in Minqin basin is excessively pumped, thus the groundwater depth is growing larger with the increasing span of time. In this paper,according to the data of monthly groundwater level from 1999 to 2008 provided by Minqin monitoring network,using the function of geo-statistical spatial analysis which is the part of Geographic Information System technique, the spatio-temporal patterns and spatial heterogeneity of groundwater depth is analyzed in recent 10 a. The interpolation results shows that the groundwater depth in Minqin Basin is growing larger yearly from 1999 to 2008.And the four funnel of groundwater depressions had appeared in 1999 and was gradually expanded and finally formed two biggest funnel of groundwater depressions when merging with nearby funnel in 2008. One-dimensional linear regression model has been established,and the results shows that the groundwater depth increases 0.52 meter every year. The values of C0 /（C0 ＋ C）（Nugget/Sill）are far less than 25% in 10 a and this means the groundwater depth in Minqin Basin has a highly spatial relativity. The value of Sill increases every year which means that the Spatial heterogeneity of groundwater depth is increasing and the influence of human activities on groundwater has gradually became structural rather than random and will leading to the augmentation of the connectivity and frangibility of groundwater in Minqin Basin . The chief reason of this phenomenon is that the groundwater over-pumped every year. So in areas where groundwater has already been overdrawn,effective measures shall be taken,such as to readjust the crop structure and enlarge the proportion of low water consumptive crops to protect groundwater resources in Minqin Basin.