Advanced satellite radar interferometry for ground surface displacement detection

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Copyright: Ng, Alex Hay-Man
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Abstract
This dissertation demonstrates the applicability of the spaceborne interferometric synthetic aperture radar (InSAR) technique for measuring the ground surface displacement at various temporal and spatial scales. The dissertation focuses on optimisation of the InSAR technique for ground deformation monitoring applications due to earthquakes, underground mining, and groundwater extraction activities. There are four main factors which have limited the use of InSAR techniques for ground surface displacement monitoring. These four factors have been discussed and investigated in this dissertation, namely: (1) temporal and spatial decorrelation, (2) phase discontinuity due to rapid deformation, (3) atmospheric disturbances, and (4) retrieval of the 3D deformation vector. SAR satellite missions with longer radar wavelength, higher incident angle and finer ground imaging resolution are preferred in order to minimise the impact of the first two limitations. An approach has been developed and implemented to address the third limitation using small-stack SAR interferograms. Investigations to the fourth limitation have been carried out using InSAR pairs acquired from different viewing geometries to map the displacement due to underground mining in three dimensions. Persistent Scatterer Interferometry (PSI) is a SAR analysis technique which utilises long time series of interferometric SAR image data. A modified PSI technique has been proposed in this dissertation to enhance the utility of the conventional PSI technique. The main features of the proposed technique are: (1) improvement in the estimation and removal of orbital error and atmospheric error components, (2) improvement in the precision of PS point identification and the displacement estimated from the less reliable PS candidates, and (3) maximisation of total PS point identified while preserving accuracy. The capability of the proposed technique for urban subsidence monitoring has been demonstrated using both ENVISAT ASAR data and ALOS PALSAR data over Beijing City, China. Cross-validation has been carried out between the results obtained from both datasets. Good correlations have been observed from the PSI results from both datasets. The ENVISAT ASAR results showed good agreement with the continuous GPS measurements. The line-of-sight displacement rates derived from the results generated by both datasets were used to derive the vertical and horizontal displacement rates.
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Author(s)
Ng, Alex Hay-Man
Supervisor(s)
Ge, Linlin
Rizos, Chris
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Publication Year
2010
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
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