Ground Deformation of Wuhan, China, Revealed by Multi-Temporal InSAR Analysis

Abstract

Wuhan, the largest city in central China, has experienced rapid urban development leading to land subsidence as well as environmental concerns in recent years. Although a few studies have analyzed the land subsidence of Wuhan based on ALOS-1, Envisat, and Sentinel-1 datasets, the research on long-term land subsidence is still lacking. In this study, we employed multi-temporal InSAR to investigate and reveal the spatiotemporal evolution of land subsidence over Wuhan with ALOS-1, Envisat, and Sentinel-1 images from 2007–2010, 2008–2010, 2015–2019, respectively. The results detected by InSAR were cross-validated by two independent SAR datasets, and leveling observations were applied to the calibration of InSAR-derived measurements. The correlation coefficient between the leveling and InSAR has reached 0.89. The study detected six main land subsidence zones during the monitoring period, with the maximum land subsidence velocity of −46 mm/a during the 2015–2019 analysis. Both the magnitude and the extent of the land subsidence have reduced since 2017. The causes of land subsidence are discussed in terms of urban construction, Yangtze river water level changes, and subsurface water level changes. Our results provide insight for understanding the causes of land subsidence in Wuhan and serve as reference for city management for reducing the land subsidence in Wuhan and mitigating the potential hazards.

Land Subsidence in Wuhan Revealed Using a Non-Linear PSInSAR Approach with Long Time Series of COSMO-SkyMed SAR Data

“…During the period from 2012 to 2019, Wuhan completed the construction of many subway lines, such as Metro Lines 3, 6, 7, 8, 11, and 21, basically completing the full coverage in the main urban area. As demonstrated in the InSAR literature [44] and in Wuhan [21], subway tunneling can induce the settlement of the ground above the line, inevitably causing surface subsidence. One typical area for these phenomena is the Xinrong area, through which Metro Lines 1 and 21 pass (Figure 5a).…”

“…Our focus on the dynamics affecting the HH, XR, and SIGG areas, instead of a wider investigation across Wuhan, is an intentional choice that is intended to provide a novel contribution to the existing InSAR literature on Wuhan and not to duplicate previous studies that have already unveiled the spatial correlation with the surface geology and distribution of the metro lines, as well as the temporal correlation with Yangtze River water level [6,21]. [24]).…”

“…This is the longest SAR time series ever analyzed over Wuhan to study land subsidence, regardless of the operation band. In the literature, the longest single-geometry SAR stack consisted of 104 scenes of ascending-mode C-band Sentinel-1 from April 2015 to June 2019 [21], while the only published InSAR study of land subsidence using COSMO-SkyMed over the city was limited to 45 images from June 2013 to June 2014 [10].…”

“…Google Earth was used to get the optical images corresponding to the settlement time series and to detect the change in urban construction in the study area. To avoid duplication of other studies that have already specifically analyzed groundwater levels of aquifer wells, water levels of the Yangtze River, and leveling benchmarks [6,21], the analysis of these data is not repeated in the present paper.…”

“…On this basis, more recently, Benattou et al [7] and Zhang et al [8] attempted an analysis of a three-year-long period using 54 Sentinel-1 and 20 RADARSAT-2 C-band SAR images acquired in 2015-2018, respectively. The latest study was by Han et al [21], who used the multi-temporal dataset method to monitor the Wuhan area for the first time, processing 19 ALOS-1 L-band scenes from January 2007 to October 2010, three ENVISAT C-band scenes from December 2008 to May 2010, and 104 Sentinel-1 scenes from April 2015 to June 2019. These authors attempted to investigate land subsidence in a multi-temporal dimension, although with different datasets with temporal gaps in between.…”