Recent Surface Deformation in the Tianjin Area Revealed by Sentinel-1A Data

Abstract

In this study, we employed multitemporal InSAR (Interferometric Synthetic Aperture Radar) (MT-InSAR) to detect spatial and temporal ground deformations over the whole Tianjin region in the North China Plain area. Twenty-five ascending Sentinel-1A terrain observation by progressive scans (TOPS) synthetic aperture radar (SAR) scenes covering this area, acquired from 9 January 2016 to 8 June 2017, were processed using InSAR time series analysis. The deformation results derived from Sentinel-1A MT-InSAR were validated with continuously operating reference stations (CORS) at four sites and four stations of the Crustal Movement Observation Network of China (CMONOC). The overall results show good agreement, demonstrating the suitability of applying Doris with Sentinel-1A data to high-resolution monitoring of surface deformation. Significant deformation variations have been observed in different parts of Tianjin. These gradually increased from the central part of the metropolitan area to the nearby suburbs. The deformation rate of the main urban area is well-balanced and it is also relatively linear, with uplifting rates ranging from 0 to 20 mm/yr. However, due to the diversity of the geological conditions and anthropogenic activities, remarkable signs of subsidence were found in several parts of Tianjin. In particular, the south-western part of Wuqing District and western part of Beichen District showed subsidence rates of up to −136 mm/yr. We also found that, in addition to groundwater over-exploitation and lithological characteristics, additional factors also influence ground subsidence, including dynamic loads (e.g., railways), static loads (e.g., urban construction), and groundwater recharging.

Land Subsidence and Ground Fissures in Beijing Capital International Airport (BCIA): Evidence from Quasi-PS InSAR Analysis

“…Figure 4 illustrates all the PS points detected by the QPS-InSAR approach, colored with the corresponding vertical displacement (cm). The displacements were relative to a reference point in Figure 1a and calibrated by Equation (2). In this study, negative values in all the figures indicate downward movement of the ground, while positive values indicate uplift.…”

“…Land subsidence occurs in over 150 countries all over the world, particularly in densely populated metropolitan areas, such as big cities in China [1][2][3], Japan [4], Italy [5], Mexico [6,7], and Indonesia [8,9], with extremely serious consequences. Beijing, one of the largest cities in the world, has suffered from land subsidence since the 1950s [10].…”

Recent Ground Subsidence in the North China Plain, China, Revealed by Sentinel-1A Datasets

“…Accordingly, variants of the MT-InSAR technique, such as persistent scatterer InSAR (PS-InSAR) [23,24] and small baseline subset (SBAS) [25], have been successfully leveraged to analyze the time-series characteristics of land subsidence. Hence, considering the advantages of InSAR, this technique has been widely used to monitor subsidence areas throughout the NCP [26][27][28][29][30][31][32][33]. However, detailed InSAR subsidence studies always focus on specific sites, often Beijing, Tianjin, and Cangzhou.…”

Investigating Ground Subsidence and the Causes over the Whole Jiangsu Province, China Using Sentinel-1 SAR Data

“…Internationally, the S-1 IW data has been used to map ground deformations over the entirety of Germany [18] and over the whole of Italy [19]. In China, most ground deformation monitoring efforts using S-1 IW data have covered relatively small areas, such as the Xiamen Airport [20] and Tianjin [21]. Therefore, the potential of S-1 IW data in monitoring ground deformation in wide areas in China has not been fully exploited.…”