Abstract
The effects of ground deformation pose a significant geo-hazard to the environment and infrastructure in Wuhan, the most populous city in Central China, in the eastern Jianghan Plain at the intersection of the Yangtze and Han rivers. Prior to this study, however, rates and patterns of region-wide ground deformation in Wuhan were little known. Here we employ multi-temporal SAR interferometry to detect and characterize spatiotemporal variations of ground deformation in major metropolitan areas in Wuhan. A total of twelve TerraSAR-X images acquired during 2009–2010 are used in the InSAR time series analysis. InSAR-derived results are validated by levelling survey measurements and reveal a distinct subsidence pattern within six zones in major commercial and industrial areas, with a maximum subsidence rate up to −67.3 mm/year. A comparison analysis between subsiding patterns and urban developments as well as geological conditions suggests that land subsidence in Wuhan is mainly attributed to anthropogenic activities, natural compaction of soft soil, and karst dissolution of subsurface carbonate rocks. However, anthropogenic activities related to intensive municipal construction and industrial production have more significant impacts on the measured subsidence than natural factors. Moreover, remarkable signals of secular land uplift are found along both banks of the Yangtze River, especially along the southern bank, with deformation rates ranging mostly from +5 mm/year to +17.5 mm/year. A strong temporal correlation is highlighted between the detected displacement evolutions and the water level records of the Yangtze River, inferring that this previously unknown deformation phenomenon is likely related to seasonal fluctuations in water levels of the Yangtze River.
Highlights
Accompanying large-scale urbanization and industrialization during the past 35 years, more than 95 megacities in China have undergone rapid land subsidence [1]
The annual deformation rates of slowly-decorrelating filtered phase (SDFP) pixels relative to the reference point range from67.3 mm/year to +17.5 mm/year
We found that noticeable land subsidence occurred widely in major urban areas of Wuhan and the average measured rates of subsidence ranged from approximately5 mm/year to67.3 mm/year during the period of observation
Summary
Accompanying large-scale urbanization and industrialization during the past 35 years, more than 95 megacities in China have undergone rapid land subsidence [1]. The potential consequences of land subsidence mainly include degradation of the aquifer system and damage to the utility infrastructures, buildings, railroads, highways and bridges [2,3]. In this context, intensive efforts and investigations related to land subsidence monitoring have been untaken in four major subsiding regions in China: the Yangtze River Delta [4,5], the North China Plain [6,7], the Fenwei Basin [8] and the Pearl Delta [9].
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