基于GRACE重力卫星的北京市地下水变化及归因分析

Variation in groundwater storage in beijing and attribution analysis based on GRACE data

摘要

【目的】北京市水资源形势不容乐观，地下水作为主要供水水源，长期被超量开采，为及时掌握地下水位时空演变规律，【方法】以2002—2022年GRACE重力卫星和地下水监测井数据为基础，运用COK模型，反演北京市地下水位变化，并从土地利用、气候变化和生态补水等方面定量分析影响地下水位变化的原因。【结果】结果表明：GRACE和实测地下水位数据反演结果的均方根误差为0~10 m,反演结果较为可靠；北京市地下水水位自2002年开始持续大幅下降，2015年至历史低值；自2014年底南水北调中线江水进京等措施使得地下水开采量逐年减少，截至2022年地下水埋深持续回升。从年内变化来看，1—2月地下水位相对稳定，3—6月逐月下降，7—10月受降雨等因素影响，地下水位明显上升；11—12月，地下水位变化不大；而空间维度上，全市地下水位以中轴线及延长线为界，呈现条带状，南北差异明显；影响北京市地下水位变化的主导因素有降雨量(q=20.14%)和生态补水(q=11.98%),显著大于土地利用类型(q=3.96%)。【结论】GRACE重力卫星反演的北京市地下水动态变化与实测结果一致，降水及生态补水是影响地下水动态变化的主要因素，研究成果对区域水循环演变规律认识及水资源管理与开发利用具有重要的现实意义，可为科学评估与合理利用地下水提供有效支撑。

Abstract

[Objective] In order to timely grasp the spatiotemporal evolution law of groundwater level, [Methods] based on the GRACE gravity satellite and groundwater monitoring well data from 2002 to 2022, the COK model is used to invert the changes in groundwater level in Beijing, and the reasons affecting groundwater level changes are quantitatively analyzed from the aspects of land use, climate change, and ecological replenishment. [Results] The result show that the root mean square error of the inversion result of GRACE and measured groundwater level data is only 0-10 m, indicating that the inversion result are relatively reliable. The groundwater level in Beijing has been continuously and significantly declining since 2002, reaching historical lows from 2015. Since the middle route of the South to North Water Transfer Project was introduced to Beijing at the end of 2014, the mining output of groundwater has decreased year by year, and the groundwater depth has continued to rise by 2022. The groundwater level remained relatively stable from January to February of the year, gradually decreasing from March to June, and significantly rising from July to October due to factors such as rainfall. From November to December, there is little change in groundwater level; In terms of spatial dimension, the groundwater level in the city is divided by the central axis and extension line, presenting a strip like pattern with significant differences between the north and south. The main factors affecting groundwater level changes in Beijing are rainfall(q=20.14%) and ecological replenishment(q=11.98%), which are significantly greater than land use types(q=3.96%). [Conclusion] The results of this study have important practical significance for understanding the evolution laws of regional water cycle under changing environments, as well as water resource management and development utilization. They can provide effective support for scientific evaluation and rational utilization of groundwater.

关键词

地下水埋深 / GRACE重力卫星 / 时空变异特征 / 北京市 / Co-Kriging法 / 水资源 / 气候变化 / 降雨

Key words

groundwater depth / GRACE gravity satellite / spatiotemporal variability characteristics / Beijing / Co-Kriging method / water resources / climate change / rainfall

基金资助

国家自然科学基金项目(42271394)