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

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.

Keywords

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