Department of Natural Resources Sciences, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, Canada H9X 3V9.
School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1.
Sci Total Environ. 2019 Jun 1;667:419-426. doi: 10.1016/j.scitotenv.2019.02.294. Epub 2019 Feb 25.
Groundwater is a most accessible freshwater resource for human beings, and it is increasingly important as an alternative to surface water under the threat of climate change. However, its complex spatio-temporal dynamic remains unattended from management perspective. Past studies on groundwater management were stalled by a relative dearth of high-quality data and a lack of synthetic analysis on both spatial and temporal information. Thanks to NASA's launch of Gravity Recovery and Climate Experiment (GRACE) satellite mission, our study has solved these two problems by innovatively applying time stability analysis to GRACE-based groundwater data. Taking the Yellow River Basin (YRB) as an example, we employed GRACE satellite data to obtain monthly changes of groundwater tables from Jan. 2003 to Dec. 2016 in 1.0-degree grid of spatial resolution. Then we identified hotspots (which indicated severe groundwater declines and fluctuations over time) and representative monitoring areas (which stably represented the spatial average over time) using time stability analysis. Time stability employs multiple coefficients to identify the spatial relations between local variables and global variables overtime, thus showing the overall effect of spatial-wise and temporal-wise factors but never used in groundwater studies before. Based on this innovative method, we further identified management categories across the YRB using multivariate cluster analysis. As a result, the YRB has been divided into five zones for different management strategies. We identified the hotspots in west-most and east-most areas of the YRB, where we suggest a strengthened groundwater protections and risk response system. The northern part of the middle reach in the YRB was also identified as the representative monitoring areas. With these knowledge, decision-makers can have a clearer regional plan for groundwater protection, monitoring, and risk response system. This new method enables a quick decision on the prioritized areas for different groundwater management strategies while not losing the scope of spatio-temporal heterogeneity.
地下水是人类最易获取的淡水资源，在气候变化的威胁下，它作为地表水的替代资源变得越来越重要。然而，从管理的角度来看，其复杂的时空动态仍然没有得到关注。过去的地下水管理研究由于高质量数据相对缺乏，以及对空间和时间信息缺乏综合分析而停滞不前。感谢美国宇航局（NASA）发射的重力恢复和气候实验（GRACE）卫星任务，我们通过创新地将时间稳定性分析应用于基于 GRACE 的地下水数据，解决了这两个问题。以黄河流域（YRB）为例，我们利用 GRACE 卫星数据，获得了 2003 年 1 月至 2016 年 12 月期间空间分辨率为 1.0 度的逐月地下水位变化。然后，我们使用时间稳定性分析识别了热点（表示随着时间的推移地下水严重下降和波动）和有代表性的监测区域（随着时间的推移稳定代表空间平均值）。时间稳定性采用多个系数来识别随时间推移局部变量与全局变量之间的空间关系，从而显示空间和时间因素的整体影响，但以前从未在地下水研究中使用过。基于这种创新方法，我们进一步使用多元聚类分析确定了黄河流域的管理类别。结果，黄河流域被划分为五个区，以采取不同的管理策略。我们确定了黄河流域最西端和最东端的热点地区，建议加强地下水保护和风险应对系统。黄河流域中游的北部地区也被确定为有代表性的监测区域。有了这些知识，决策者可以为地下水保护、监测和风险应对系统制定更清晰的区域规划。这种新方法可以快速确定不同地下水管理策略的优先区域，同时不失空间异质性的范围。
