关键词: 地面沉降, 苏州, SBAS, 时空演化特征, 沉降速率

Abstract:

The city of Suzhou is located in the well known Suzhou-Wuxi-Changzhou subsidence zone in China, which suffers from serious land subsidence. Land subsidence occurring in this area can cause conspicuous social and economic lost, thus a proper investigation is necessary for this region. In order to understand the spatial-temporal evolution of land subsidence in Suzhou, we applied the Small Baseline Subset (SBAS) Interferometric Synthetic Aperture Radar (InSAR) technique to 27 C-band ERS-2 SAR images acquired between 2007 and 2010 by European Space Agency (ESA). The results show that during the observation period, the downtown and uptown areas show a relatively slow subsidence rate, while an exceptionally rapid subsidence is detected in 3 suburb areas. The downtown area such as Gusu district and the uptown area such as Wuzhong district are characterized by their generally low subsidence rates, which are less than 10 mm/a, and there is no subsidence center detected. Land subsidence mainly occurs in Xiangcheng district, Wujiang district and the industrial park, which are the newly developed zones characterized by the subsidence rates of greater than 10 mm/a. We observe the prevalence of ground subsidence phenomena ranging from 10 mm/a up to 20 mm/a in Xiangcheng district, while in certain towns and streets, the subsidence phenomenon is significantly severe with a rate close to 20 mm/a or higher. The maximum accumulative subsidence in the industrial park reaches 50 mm, and the average subsidence rate of this area is approximately 20 mm/a. Rapid subsidence with an average rate being up to 20 mm/a is observed in Wujiang district, which is located in the southern part of Suzhou. The land subsidence in this area is the severest within the whole research area, featured by its large coverage and high subsidence rate, and the maximum accumulative subsidence displacement can reach 60 mm or more.

Key words: land subsidence, Suzhou, SBAS, spatial-temporal evolution, subsidence rate