Abstract
Interferometric synthetic aperture radar (InSAR) mapping of localized ground surface deformation has become an important tool to manage subsidence-related geohazards. However, monitoring land surface deformation using InSAR at high spatial resolution over a large region is still a formidable task. In this paper, we report a research on investigating ground subsidence and the causes over the entire 107, 200 km2 province of Jiangsu, China, using time-series InSAR. The Sentinel-1 Interferometric Wide-swath (IW) images of 6 frames are used to map ground subsidence over the whole province for the period 2016–2018. We present processing methodology in detail, with emphasis on the three-level co-registration scheme of S-1 data, retrieval of mean subsidence velocity (MSV) and subsidence time series, and mosaicking of multiple frames of results. The MSV and subsidence time series are generated for 9,276,214 selected coherent pixels (CPs) over the Jiangsu territory. Using 688 leveling measurements in evaluation, the derived MSV map of Jiangsu province shows an accuracy of 3.9 mm/year. Moreover, subsidence causes of the province are analyzed based on InSAR-derived subsidence characteristics, historical optical images, and field-work findings. Main factors accounting for the observed subsidence include: underground mining, groundwater withdrawal, soil consolidations of marine reclamation, and land-use transition from agricultural (paddy) to industrial land. This research demonstrates not only the capability of S-1 data in mapping ground deformation over wide areas in coastal and heavily vegetated region of China, but also the potential of inferring valuable knowledge from InSAR-derived results.
Highlights
Jiangsu province is located at the center of the eastern China coast area and in the Yangtze river delta region
We report a research on mapping the ground subsidence and inferring the causes for the entire Jiangsu province for the period 2016–2018 with S-1 Interferometric Wide-swath (IW) data
From the Sentinel-1 data archive accessed through the Copernicus Open Access Hub, the descending S-1 acquisitions over Jiangsu province are very sparse and far less than the requirement for TS-Interferometric synthetic aperture radar (InSAR) analysis
Summary
Jiangsu province is located at the center of the eastern China coast area and in the Yangtze river delta region. Given the advanced shipping network composed by the Yangtze River, the Beijing-Hangzhou Grand Canal and other numerous inland rivers/canals, and the high percentage of cultivatable land, the Jiangsu province has been the most prosperous region in China for many centuries. It is reported that 5000 km area has accumulative subsidence larger than 0.2 m, and the maximum accumulative subsidence reached 2 m until the year 2000 in the Suzhou-Wuxi-Changzhou region of southern Jiangsu [1]. In order to cope with the threat posed by the increasingly expanding ground subsidence, the provincial government of Jiangsu issued a 10-year plan in 2014 aiming at actions
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