Monitoring reclaimed lands subsidence in Hong Kong with InSAR technique by persistent and distributed scatterers

Mingzhou, Wang; Li, Tao; Jiang, Liming

doi:10.1007/s11069-016-2196-1

Cited by 16 publications

(9 citation statements)

References 26 publications

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“…Petro-chemicals are important for Singapore’s economy—therefore, facilities were built rapidly once land had been reclaimed, with little space given for natural vegetation to establish [ 57 ]. In addition, such industrial development typically requires low-rise rather than high-rise development, which has less stringent requirements on soil stability and structure, and so can proceed more rapidly after reclamation [ 58 ]. The Tuas site will be developed for port infrastructure in future, with much of the reclaimed area designated for temporary container storage, cranes and warehousing [ 59 ].…”

Section: Discussionmentioning

confidence: 99%

Development of spontaneous vegetation on reclaimed land in Singapore measured by NDVI

Gaw

Richards

2021

PLoS ONE

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Population and economic growth in Asia has led to increased urbanisation. Urbanisation has many detrimental impacts on ecosystems, especially when expansion is unplanned. Singapore is a city-state that has grown rapidly since independence, both in population and land area. However, Singapore aims to develop as a ‘City in Nature’, and urban greenery is integral to the landscape. While clearing some areas of forest for urban sprawl, Singapore has also reclaimed land from the sea to expand its coastline. Reclaimed land is usually designated for future urban development, but must first be left for many years to stabilise. During the period of stabilisation, pioneer plant species establish, growing into novel forest communities. The rate of this spontaneous vegetation development has not been quantified. This study tracks the temporal trends of normalized difference vegetation index (NDVI), as a proxy of vegetation maturity, on reclaimed land sensed using LANDSAT images. Google Earth Engine was used to mosaic cloud-free annual LANDSAT images of Singapore from 1988 to 2015. Singapore’s median NDVI increased by 0.15 from 0.47 to 0.62 over the study period, while its land area grew by 71 km2. Five reclaimed sites with spontaneous vegetation development showed variable vegetation covers, ranging from 6% to 43% vegetated cover in 2015. On average, spontaneous vegetation takes 16.9 years to develop to a maturity of 0.7 NDVI, but this development is not linear and follows a quadratic trajectory. Patches of spontaneous vegetation on isolated reclaimed lands are unlikely to remain forever since they are in areas slated for future development. In the years that these patches exist, they have potential to increase urban greenery, support biodiversity, and provide a host of ecosystem services. With this knowledge on spontaneous vegetation development trajectories, urban planners can harness the resource when planning future developments.

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Section: Discussionmentioning

confidence: 99%

Development of spontaneous vegetation on reclaimed land in Singapore measured by NDVI

Gaw

Richards

2021

PLoS ONE

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“…The second site is Hong Kong Science Park (HKSP), which is situated in Pak Shek Kok, New Territories on the boundary of Sha Tin District and Tai Po District; this area is also next to the Chinese University of Hong Kong in Ma Liu Shui (see Figure 1). As a research base of approximately 9 square kilometres with superior and applied technology in Hong Kong, HKSP was reclaimed at the end of the last century, and the first phase of the project was completed in October 2004; therefore, this area still experiences land settlement even though more than twenty years have passed since the reclamation occurred [24]. As newly developed reclamation land, man-made structures are relatively scarce in this area, which were only distributed in the southeast corner of the area during the study period.…”

Section: Study Areamentioning

confidence: 99%

“…Xu et al [23] proposed an elaborated SBAS strategy to process an Envisat ASAR dataset acquired between 2007 and 2010 and analysed the evolution of land reclamation in Shenzhen. Wang et al [24] utilized an advanced SBAS method to investigate the subsidence time series of reclaimed lands in Hong Kong with TerraSAR-X images acquired between October 2008 and December 2009. Wang et al [25] combined multi-track interferograms from different viewing geometries to estimate a linear rate map for the Pearl River Delta based on the π-RATE method.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Coastal Reclamation Subsidence in Hong Kong with Distributed Scatterer Interferometry

Sun

Jiang

et al. 2018

Remote Sensing

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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.

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“…water, bare soil, grassland, etc. [14]. Successful application of DS requires statistically homogeneous pixel (SHP) identification and phase optimization.…”

Section: Introductionmentioning

confidence: 99%

Underground Coal Fires Identification and Monitoring Using Time-Series InSAR With Persistent and Distributed Scatterers: A Case Study of Miquan Coal Fire Zone in Xinjiang, China

Liu

Wang

et al. 2019

IEEE Access

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The Xinjiang is an important coal production base in China and also a serious coal fire disaster area. Coal fires not only waste resources, but also cause air pollution and damage to the ecological environment. Hence, it is very important to identify and monitor the underground coal fire areas accurately and efficiently for the control of coal fires. Interferometric synthetic aperture radar (InSAR) technology identifies and monitors coal fire areas by monitoring surface subsidence caused by burned out area. Compared with traditional coal fire monitoring technology, InSAR technology has the advantages of allweather and high efficiency. But the fire areas are often distributed in wild areas, this factor significantly limits the application of the traditional Persistent Scatterer interferometry (PSI) technology. In addition, Xinjiang coal fires are mostly located in historical goafs, so it is necessary to distinguish the subsidence caused by mining and coal fires. Therefore, distributed scatterer interferometry (DSI) technology is used to monitor the Miquan fire area in Xinjiang in this paper. The results show that compared with PSI technology, DSI technology can expand the number of effective monitoring points 124 times. On this basis, spatiotemporal analysis of surface subsidence in the study area suggests that the subsidence caused by mining and coal fires exhibits significantly different space-time evolution rules. Therefore, in the future, the coal fire area and mining area can be separated and identified according to these rules. The final identified coal fire area contains all measured coal fire points, and accurately monitors the fire extinguishing area. INDEX TERMS Coal fire monitoring, subsidence information, InSAR, spatio-temporal analysis.

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Monitoring reclaimed lands subsidence in Hong Kong with InSAR technique by persistent and distributed scatterers

Cited by 16 publications

References 26 publications

Development of spontaneous vegetation on reclaimed land in Singapore measured by NDVI

Development of spontaneous vegetation on reclaimed land in Singapore measured by NDVI

Monitoring Coastal Reclamation Subsidence in Hong Kong with Distributed Scatterer Interferometry

Underground Coal Fires Identification and Monitoring Using Time-Series InSAR With Persistent and Distributed Scatterers: A Case Study of Miquan Coal Fire Zone in Xinjiang, China

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