Abstract
As a common geological hazard, land subsidence is widely distributed in the Eastern Beijing Plain. The pattern of evolution of this geological phenomenon is controlled by many factors, including groundwater level change in different aquifers, compressible layers of different thicknesses, and static and dynamic loads. First, based on the small baseline subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique, we employed 47 ENVISAT ASAR images and 48 RADARSAT-2 images to acquire the ground deformation of the Beijing Plain from June 2003 to November 2015 and then validated the results using leveling benchmark monitoring. Second, we innovatively calculated additional stress to obtain static and dynamic load information. Finally, we evaluated the contribution rate of the influencing factors to land subsidence by using the Spearman’s rank correlation coefficient (SRCC) and extremely randomized trees (ERT) machine learning methods. The SBAS-InSAR outcomes revealed that the maximum deformation rate was 110.7 mm/year from 2003 to 2010 and 144.4 mm/year from 2010 to 2015. The SBAS-InSAR results agreed well with the leveling benchmark monitoring results; the correlation coefficients were 0.97 and 0.96 during the 2003–2010 and 2013–2015 periods, respectively. The contribution rate of the second confined aquifer to the cumulative land subsidence was 49.3% from 2003 to 2010, accounting for the largest proportion; however, its contribution rate decreased to 23.4% from 2010 to 2015. The contribution rate of the third confined aquifer to the cumulative land subsidence increased from 2003 to 2015. Although the contribution of additional stress engendered from static and dynamic loads to the cumulative land subsidence was slight, it had a significant effect on the uneven land subsidence, with a contribution rate of 33.8% from 2003 to 2010 and 23.1% from 2010 to 2015. These findings provide scientific support for mitigating hazards associated with land subsidence.
Highlights
With the reduction in land surface elevation, land subsidence is mainly caused by the consolidation and compression of loose stratum [1,2,3]
Based on the surface displacement information measured by SBAS-Interferometric Synthetic Aperture Radar (InSAR), a land subsidence rate distribution map during the observation period was obtained for the Beijing Plain (BP)
From June 2003 to August 2010, 19,090 pixels were detected in the study area based on the ENVISAT ASAR (EA) data, with a density of 181 pixel/km2, and the average land subsidence rate varied from −110.7 to +8.3 mm/year
Summary
With the reduction in land surface elevation, land subsidence is mainly caused by the consolidation and compression of loose stratum [1,2,3]. The cities affected by land subsidence in China are mainly distributed in the Yangtze River Delta, the Fenwei Basin, and the North China Plain [1,9]. Among these areas, the most serious land subsidence occurs in the central and northern regions of the North China Plain, where Beijing is located [6,9]. Previous studies showed that the influencing factors of land subsidence mainly include a decline in the level of groundwater, the thickness of compressible layers, and urban static and dynamic loads [13,14]
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