Abstract
Abstract This paper describes the results from the recently launched SAR satellites for the purpose of subsidence monitoring over underground coal mine sites in the state of New South Wales, Australia, using differential interferometric synthetic aperture radar (DInSAR) technique. The quality of the mine subsidence monitoring results is mainly constrained by noise due to the spatial and temporal decorrelation between the interferometric pair and the phase discontinuities in the interferogram. This paper reports on the analysis of the impact of these two factors on the performance of DInSAR for monitoring ground deformation. Simulations were carried out prior to real data analyses. SAR data acquired using different operating frequencies, for example, X-, C- and L-band, from the TerraSAR-X, ERS-1/2, ENVISAT, JERS-1 and ALOS satellite missions, were examined. The simulation results showed that the new satellites ALOS, TerraSAR-X and COSMO-SkyMed perform much better than the satellites launched before 2006. ALOS and ENVISAT satellite SAR images with similar temporal coverage were searched for the test site. The ALOS PALSAR DInSAR results have been compared to DInSAR results obtained from ENVISAT ASAR data to investigate the performance of both satellites for ground subsidence monitoring. Strong phase discontinuities and decorrelation have been observed in almost all ENVISAT interferograms and hence it is not possible to generate the displacement maps without errors. However these problems are minimal in ALOS PALSAR interferograms due to its spatial resolution and longer wavelength. Hence ALOS PALSAR is preferred for ground subsidence monitoring in areas covered by vegetation and where there is a high rate ground deformation.
Highlights
Ground subsidence is the lowering or collapse of the land surface which can be caused by either natural or anthropogenic activities
Discussions and Conclusions The performance of recently launched SAR satellites for ground subsidence monitoring purposes was investigated in this study
The impact of decorrelation and phase discontinuity for mine subsidence monitoring applications could be minimised by having SAR satellite missions with longer radar wavelength, greater incident angle and finer ground imaging resolution
Summary
Ground subsidence is the lowering or collapse of the land surface which can be caused by either natural or anthropogenic activities. Due to insufficient DInSAR results derived from various orbits and look angles, it is assumed in this paper that the horizontal deformation is negligible for the ease of calculation Based on this assumption, the line-of-sight displacement can be converted into vertical displacement by: S. where S is the surface displacement in the vertical direction. The quality of ground subsidence monitoring using radar interferometry is mainly constrained by noise due to the spatial and temporal decorrelation between the interferometric pair and the phase discontinuities in the interferogram. In this study these two factors are used to analyse the performance of different satellites for monitoring ground deformation. Assuming a subsidence bowl with radius 150 m, theoretically the maximum deformation that can be detected (without phase discontinuity) is approximately 8 cm, 7 cm, 48 cm, 86 cm, 39 cm and 39 cm for the wavelengths of ERS, ENVISAT, JERS-1, ALOS, TerraSAR-X and COSMO-SkyMed satellites respectively, along the slant-range direction
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