Multi-temporal SAR observations of the Surat Basin in Australia for deformation scenario evaluation associated with man-made interactions

Human activities for extracting natural resources, may lead to subsequent gradual or abrupt surface deformation, with adverse effects in the local ecosystem and damage to man-made structures. Over the past two decades, interferometric SAR (InSAR) has been demonstrated as the optimal remote sensing technique to estimate surface deformation with high spatial coverage and vertical accuracy over traditional surveying methods. In this paper, the outcome of advanced differential InSAR processing to detect and analyze ground surface behavior due to manmade interactions are presented. An improvement was achieved in the temporal resolution and accuracy using a unique combination of both C-band and L-band SAR satellite acquisitions with different temporal and spatial baselines. The two alternate DInSAR methodologies were applied on the northeastern part of the Surat Basin, Australia for an area without long-term ground-based geodetic observations. The regions undergoing downward motion are located above coal seam gas (CSG) mining sites with rates up to 28 mm/year. Three scenarios were identified: (1) extensive groundwater extraction from shallow aquifers due to CSG mining, (2) CSG mining without direct impact on groundwater resources and (3) patchy uplift over an industrial forest adjacent to a CSG mining district. Contrary to a previous study conducted in this region using the PSInSAR technique which reported stability of the area with insignificant surface deformation, this study shows that there are considerable deformation signals consistent with resource extraction. Consequently, it is shown that the SBAS approach is superior to PSInSAR for deformation monitoring with focusing on naturally distributed scatterers.