Evolution of Secondary Deformations Captured by Satellite Radar Interferometry: Case Study of an Abandoned Coal Basin in SW Poland

Abstract

The issue of monitoring surface motions in post-mining areas in Europe is important due to the fact that a significant number of post-mining areas lie in highly-urbanized and densely-populated regions. Examples can be found in: Belgium, the Czech Republic, France, Germany, the Netherlands, Spain, the United Kingdom, as well as the subject of this study, the Polish Walbrzych Hard Coal Basin. Studies of abandoned coal fields show that surface deformations in post-mining areas occur even several dozen years after the end of underground coal extraction, posing a threat to new development of these areas. In the case of the Walbrzych area, fragmentary, geodetic measurements indicate activity of the surface in the post-mining period (from 1995 onward). In this work, we aimed at determining the evolution of surface deformations in time during the first 15 years after the end of mining, i.e., the 1995–2010 period using ERS 1/2 and Envisat satellite radar data. Satellite radar data from European Space Agency missions are the only source of information on historical surface movements and provide spatial coverage of the entirety of the coal fields. In addition, we attempted to analyze the relationship of the ground deformations with hydrogeological changes and geological and mining data. Three distinct stages of ground movements were identified in the study. The ground motions (LOS (Line Of Sight)) determined with the PSInSAR (Persistent Scatterer Interferometry) method indicate uplift of the surface of up to +8 mm/a in the first period (until 2002). The extent and rate of this motion was congruent with the process of underground water table restoration in separate water basins associated with three neighboring coal fields. In the second period, after the stabilization of the underground water table, the surface remained active, as indicated by local subsidence (up to −5 mm/a) and uplift (up to +5 mm/a) zones. We hypothesize that this surface activity is the result of ground reaction disturbed by long-term shallow and deep mining. The third stage is characterized by gradual stabilization and decreasing deformations of the surface. The results accentuate the complexity of ground motion processes in post-mining areas, the advantages of the satellite radar technique for historical studies, and provide information for authorities responsible for new development of such areas, e.g., regarding potential flood zones caused by restoration of groundwater table in subsided areas.

Land Subsidence Estimation for Aquifer Drainage Induced by Underground Mining

“…Land subsidence due to mining is mainly caused by removing a deposit from a rock mass and forming a post-mining void [46]. This type of land subsidence can damage the surface and underground infrastructure and endanger surface users' safety [8,[47][48][49][50][51]. Land subsidence's spatial extent and value are primarily determined by the depth of exploitation, seam thickness, panel dimensions, overlying rock mass geomechanical conditions, geological defects, surface topography, production methods and post-mining void reclamation method [30,52,53].…”

“…Land subsidence's spatial extent and value are primarily determined by the depth of exploitation, seam thickness, panel dimensions, overlying rock mass geomechanical conditions, geological defects, surface topography, production methods and post-mining void reclamation method [30,52,53]. Many research papers have been presented in recent years documenting the land subsidence phenomenon caused by mining [47,49,[54][55][56][57][58][59][60][61][62][63]. As a result, one can be stated that the spatial extent of the phenomenon can range from several km 2 [49] to tens of km 2 [15], while its values can range from a few mm/year [64] to several cm/day [65].…”

“…Many research papers have been presented in recent years documenting the land subsidence phenomenon caused by mining [47,49,[54][55][56][57][58][59][60][61][62][63]. As a result, one can be stated that the spatial extent of the phenomenon can range from several km 2 [49] to tens of km 2 [15], while its values can range from a few mm/year [64] to several cm/day [65].…”

Diagnosing Subsidence Geohazard at Beijing Capital International Airport, from High-Resolution SAR Interferometry

“…Monitoring and controlling the subsidence of runways are of great significant to ensure the safe operation of the whole airport and avoid the potential extensive loss of life and property.During the last three decades, interferometric synthetic aperture radar (InSAR) technology has developed into a powerful tool, providing high-resolution, day-and-night, weather-independent wide-coverage and high-accuracy measurements of the earth surface [6]. It has been widely used in various applications, such as the displacements monitoring of city subsidence [7][8][9][10][11][12], important infrastructures [13][14][15][16] and landslides geohazards [17][18][19][20][21]. Compared to traditional geodetic measuring methods-e.g., leveling and global positioning system (GPS)-InSAR measurements do not need any on-site installation and power supply, thus they will not have any impact on the regular operation of the airport.…”

Sustainable Applications of Remote Sensing and Geospatial Information Systems to Earth Observations

“…Blachowski et al [12], in their paper entitled "Evolution of Secondary Deformations Captured by Satellite Radar Interferometry: Case Study of an Abandoned Coal Basin in SW Poland", used multi-temporal ERS-1, ERS-2, and Envisat C-band synthetic aperture radar (SAR) images to analyze ground movements of an enclosed coal mining basin known as Walbrzych Coal Basin in the southwestern part of Poland from 1995 to 2010. The results showed that (1) the post-mining ground motion process is very complex, and (2) the SAR interferometric (InSAR) technique has a distinct advantage that it can be used for historical studies.…”