Subsidence Monitoring over the Southern Coalfield, Australia Using both L-Band and C-Band SAR Time Series Analysis

Abstract

Land subsidence is a global issue and researchers from all over the world are keen to know the causes of deformation and its further influences. This paper reports the findings from time series InSAR (TS-InSAR) results over the Southern Coalfield, Australia using both ALOS-1 PALSAR (Phased Array type L-band Synthetic Aperture Radar) and ENVISAT ASAR (Advanced Synthetic Aperture Radar) datasets. TS-InSAR has been applied to both rural and urban areas with great success, but very few of them have been applied to regions affected by underground mining activities. The TS-InSAR analysis exploited in this paper is based on GEOS-ATSA, and Measurement Point (MP) pixels are selected according to different geophysical features. Three experiment sites with different geological settings within the study zone are analysed: (1) Wollongong city, which is a relatively stable area; (2) Tahmoor town, a small town affected by underground mining activities; and (3) the Appin underground mining site, a region containing multiple underground mining activities. The TS-InSAR results show that the performance of both C-band and L-band is equally good over Wollongong, where the subsidence gradient is not significant and most subsidence rates are between´10 mm¨yr´1 to 10 mm¨yr´1. However, over the Tahmoor and Appin sites, difference in performances has been observed. Since the maximum displacement gradients that can be detected are different for L-band and C-band-based TS-InSAR methods, some rapid changes could cause the TS-InSAR to fail to estimate the correct displacements. It is well known that L-band can perform better than C-band, especially in underground mining regions and mining-affected regions where the deformation rate is much higher than city areas because of its wavelength. Statistical analyses are also conducted to further prove the above statement.

Monitoring of Land-Surface Deformation in the Karamay Oilfield, Xinjiang, China, Using SAR Interferometry

“…The RMSE values can be used to compare the individual model performance to that of other predictive models; it is often used in the field of geosciences, where researchers use the RMSE for model errors and comparison [45][46][47].…”

Wuhan Surface Subsidence Analysis in 2015–2016 Based on Sentinel-1A Data by SBAS-InSAR

“…Surface subsidence is one of the main engineering geological problems worldwide, and it is caused by consolidation and compression of underground unconsolidated strata because of non-human-related (e.g., earthquake and natural consolidation of soil) or human-related (e.g., groundwater extraction and underground construction) activities [1][2][3]. Surface subsidence is also one of the major regional geological disasters that cause serious damage to buildings, infrastructures, roads, and bridges and affect human safety in cities [4][5][6].…”

First Results from Sentinel-1A InSAR over Australia: Application to the Perth Basin

“…Other peer-reviewed InSAR studies of Australia document ground deformation induced by anthropogenic activities, predominantly underground longwall coal mining in New South Wales, which is linked to horizontal and vertical displacements of 10 s of mm/y and 100 s of mm/y, respectively [32][33][34][35][36] (Figure 1). Elsewhere, regional-scale InSAR surveys have been implemented, including in the Gippsland Basin, Victoria.…”

“…Such increases in data coverage will aid in enabling wider application of InSAR to measure ground deformation driven by anthropogenic and geological/hydrogeological factors. Map showing the distribution of past peer-reviewed InSAR studies over Australia: longwall mining in New South Wales [32][33][34][35][36]; seismicity in Western Australia [30,31]; and regional-scale studies in the Gippsland Basin, Victoria [37] and the Surat Basin, Queensland [38]. Blue and green coloured regions show where, at the time of writing, more than 10 Sentinel-1A scenes have been acquired.…”