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Open AccessArticle

Monitoring Coastal Reclamation Subsidence in Hong Kong with Distributed Scatterer Interferometry

1
State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, 340 XuDong Rd, Wuhan 430077, China
2
University of Chinese Academy of Sciences, 19A Yuquan Rd., Beijing 100049, China
3
School of Earth Science and Engineering, Hohai University, 1 Xikang Rd., Nanjing 210098, China
4
Institute of Space and Earth Information Science, Chinese University of Hong Kong, Shatin, N.T., Hong Kong 999077, China
5
Geography and Resource Management, Chinese University of Hong Kong, Shatin, N.T., Hong Kong 999077, China
*
Author to whom correspondence should be addressed.
Remote Sens. 2018, 10(11), 1738; https://doi.org/10.3390/rs10111738
Received: 30 August 2018 / Revised: 29 October 2018 / Accepted: 1 November 2018 / Published: 3 November 2018
(This article belongs to the Special Issue Imaging Geodesy and Infrastructure Monitoring)
Land subsidence has been a significant problem in land reclaimed from the sea, and it is usually characterized by a differential settlement pattern due to locally unconsolidated marine sediments and fill materials. Time series Synthetic Aperture Radar Interferometry (InSAR) techniques based on distributed scatterers (DS), which can identify sufficient measurement points (MPs) when point-wise radar targets are lacking, have great potential to measure such differential reclamation settlement. However, the computational time cost has been the main drawback of current distributed scatterer interferometry (DSI) for its applications compared to the standard PSI analysis. In this paper, we adopted an improved DSI processing strategy for a fast and robust analysis of land subsidence in reclaimed regions, which is characterized by an integration of fast statistically homogeneous pixel selection based (FaSHPS-based) DS detection and eigendecomposition phase optimization. We demonstrate the advantages of the proposed DSI strategy in computational efficiency and deformation estimation reliability by applying it to two TerraSAR-X image data stacks from 2008 to 2009 to retrieve land subsidence over two typical reclaimed regions of Hong Kong International Airport (HKIA) and Hong Kong Science Park (HKSP). Compared with the state-of-the-art DSI methods, the proposed strategy significantly improves the computational efficiency, which is enhanced approximately 30 times in DS identification and 20 times in phase optimization. On average, the DSI strategy results in 7.8 and 3.7 times the detected number of MPs for HKIA and HKSP with respect to persistent scatter interferometry (PSI), which enables a very detailed characterization of locally differential settlement patterns. Moreover, the DSI-derived results agree well with the levelling survey measurements at HKIA, with a mean difference of 1.87 mm/yr and a standard deviation of 2.08 mm/yr. The results demonstrate that the proposed DSI strategy is effective at improving target density, accuracy and efficiency in monitoring ground deformation, particularly over reclaimed coastal areas. View Full-Text
Keywords: Synthetic Aperture Radar Interferometry (InSAR); persistent scatterers; distributed scatterers; efficiency; reclamation subsidence; Hong Kong Synthetic Aperture Radar Interferometry (InSAR); persistent scatterers; distributed scatterers; efficiency; reclamation subsidence; Hong Kong
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MDPI and ACS Style

Sun, Q.; Jiang, L.; Jiang, M.; Lin, H.; Ma, P.; Wang, H. Monitoring Coastal Reclamation Subsidence in Hong Kong with Distributed Scatterer Interferometry. Remote Sens. 2018, 10, 1738.

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