Control and influence of rising groundwater level on land under the background of South-to-North Water Diversion: A case study of Chaobai River groundwater system in Beijing

This paper is the result of hydrogeological survey engineering.

Objective Overexploitation of groundwater in Beijing has caused serious land subsidence since the 1980s. After the south water entered Beijing in 2014, closure of self-contained water-source well and water-source replacement, groundwater mining restriction, and ecological water supplement carried out on a large scale in Beijing led to a significant rise in groundwater table.Ground subsidence slowed down, and even rebounded in some areas. Response of ground subsidence to groundwater table rise is a complicated process. The relevant research is of great significance to the prevention and control of land subsidence in Beijing, further providing reference for the prevention and control of land subsidence in China.

Methods The plain area of Chaobai River Basin was selected in this study, and the spatial monitoring of regional land subsidence and groundwater was carried out by using synthetic aperture radar interferometry, land subsidence layered mark monitoring technology and groundwater layered monitoring technology to verify the response characteristics of land subsidence to the rising groundwater table.

Results (1) With the recharge of Chaobai River groundwater, the maximum water table of the first and second confined aquifers returned 25.49 m and 25.67 m, respectively. (2) The maximum rebound rate and rebound range of the region from 2015 to 2020 were basically consistent with the water table contour in the groundwater rising area. (3) In the middle and upper reaches of alluvial fan of Chaobai River, the soil compression of different lithologic soil layers continued slowing down or rebounding under the groundwater table restoration mode. But the groundwater table continued declining in the downstream area where groundwater was not recharged, and the soil deformation continued compressing.

Conclusions The ecological water supplement of Chaobai River led to the increase in groundwater table, which effectively controlled the rapid trend of land subsidence development.