基于空间自相关的地下水脆弱性时空演变

Spatio-temporal Evolution of Groundwater Vulnerability Based on Spatial Autocorrelation

在人类活动较多的地区,影响地下水脆弱性的相关人为因素分布格局各时期不同,研究地下水脆弱性的时空格局转变,探求其各时期分布的特点,预测其发展的趋势,对于合理制定发展规划、针对性地降低地下水污染的风险有着重要的意义.以北京市朝阳区的水文地质和人文社会数据资料为基础,建立了基于DRASTIC模型考虑了土地利用类型等人为因素的地下水脆弱性综合评价模型.通过计算Global Moran'sⅠ指数、Getis-Ord Gi*指数(G指数)定量表征了研究区地下水脆弱性的时空格局演变,通过研究区G指数的质心和标准差椭圆定量分析了地下水脆弱性的分布特点和变化趋势.结果表明:研究区2004年、2010年和2016年高脆弱性地区面积呈逐年递减趋势,地下水脆弱性的高值聚集区主要分布在东北、西南地区,其中东北地区脆弱性逐年改善,而西北地区变化不大,造成变化的主要原因是土地利用类型的变化和化肥使用的减少.

The distribution patterns of human activities affecting groundwater vulnerability vary with time. Studying the temporal and spatial changes in groundwater vulnerability,exploring the distribution characteristics of each period,and predicting the trends of development are important to formulate an effective development plan and reduce the risk of groundwater pollution at the same time.Based on the hydrogeological data as well as humanities and social data for 2004,2010,and 2016 for the Chaoyang District of Beijing,a comprehensive evaluation model considering the human factors such as the land use types was established using the DRASTIC model.The spatiotemporal pattern of groundwater vulnerability was quantitatively characterized by calculating the Global Moran＇s Ⅰ and GetisOrd Gi＊index,and the distribution characteristics and variations in groundwater vulnerability were analyzed by the centroid of the G index and the standard deviation ellipse of the study area. The results indicate that in 2004,2010,and 2016,the areas of high vulnerability have gradually reduced. The groundwater vulnerability in the study area shows a strong spatial aggregation; high concentration areas are mainly distributed in the northeast and southwest regions. The vulnerability of the northeast region has been decreasing each year,while the vulnerability of the northwest region has not changed much. The main reasons are the land use changes and the reductions in fertilizer use.