Monitoring active open-pit mine stability in the Rhenish coalfields of Germany using a coherence-based SBAS method

With the recent progress in synthetic aperture radar (SAR) technology, especially the new generation of SAR satellites (Sentinel-1 and TerraSAR-X), our ability to assess slope stability in open-pit mines has significantly improved. The main objective of this work is to map ground displacement and slope instability over three open-pit mines, namely, Hambach, Garzweiler and Inden, in the Rhenish coalfields of Germany to provide long-term monitoring solutions for open-pit mining operations and their surroundings. Three SAR datasets, including Sentinel-1A data in ascending and descending orbits and TerraSAR-X data in a descending orbit, were processed by a modified small baseline subset (SBAS) algorithm, called coherence-based SBAS, to retrieve ground displacement related to the three open-pit mines and their surroundings. Despite the continuously changing topography over these active open-pit mines, the small perpendicular baselines of both Sentinel-1A and TerraSAR-X data were not affected by DEM errors and hence could yield accurate estimates of surface displacement. Significant land subsidence was observed over reclaimed areas, with rates exceeding 500 mm/yr, 380 mm/yr, and 310 mm/yr for the Hambach, Garzweiler and Inden mine, respectively. The compaction process of waste materials is the main contributor to land subsidence. Land uplift was found over the areas near the active working parts of the mines, which was probably due to excavation activities. Horizontal displacement retrieved from the combination of ascending and descending data was analysed, revealing an eastward movement with a maximum rate of ∼120 mm/yr on the western flank and a westward movement with a maximum rate of ∼ 60 mm/yr on the eastern flank of the pit. Former open-pit mines Fortuna-Garsdorf and Berghein in the eastern part of Rhenish coalfields, already reclaimed for agriculture, also show subsidence, at locations reaching 150 mm/yr. The interferometric results were compared, whenever possible, with groundwater information to analyse the possible reasons for ground deformation over the mines and their surroundings

Satellite based synthetic aperture radar and optical spatial-temporal information as aid for operational and environmental mine monitoring

A sustainable society is a society that satisfies its resource requirements without endangering the sustainability of these resources. The mineral endowment on the African continent is estimated to be the first or second largest of world reserves. Therefore, it is recognised that the African continent still heavily depends on mineral exports as a key contributor to the gross domestic product (GDP) of various countries. These mining activities, however, do introduce primary and secondary environmental degradation factors. They attract communities to these mining areas, light and heavy industrial establishments occur, giving rise to artisanal activities. This study focussed on satellite RS products as an aid to a mine’s operations and the monitoring of its environment. Effective operational mine management and control ensures a more sustainable and profitable lifecycle for mines. Satellite based RS holds the potential to observe the mine and its surrounding areas at high temporal intervals, different spectral wavelengths and spatial resolutions. The combination of SAR and optical information creates a spatial platform to observe and measure the mine’s operations and the behaviour of specific land cover and land use classes over time and contributes to a better understanding of the mining activities and their influence on the environment within a specific geographical area. This study will introduce an integrated methodology to collect, process and analyse spatial information over a specific targeted mine. This methodology utilises a medium resolution land cover base map, derived from Landsat 8, to understand the predominant land cover types of the surrounding area. Using very high resolution mono- and stereoscopic satellite imagery provides a finer scale analysis and identifies changes in features at a smaller scale. Combining these technologies with the synthetic aperture radar (SAR) applications for precise measurement of surface subsidence or upliftment becomes a spatial toolbox for mine management. This study examines a combination of satellite remote sensing products guided by a systematic workflow methodology to integrate spatial results as an aid for mining operations and environmental monitoring. Some of the results that can be highlighted is the successful land cover classification using the Landsat 8 satellite. The land cover that dominated the Kolomela mine area was the “SHRUBLAND/GRASS” class with a 94% coverage and “MINE” class of 2.6%. Sishen mine had a similar dominated land cover characteristic with a “SHRUBLAND/GRASS” class of 90% and “MINE” class of 4.8%. The Pléiades time-series classification analysis was done using three scenes each acquired at a different time interval. The Sishen and Kolomela mine showed especially changes from the bare soil class to the asphalt or mine class. The Pléiades stereoscopic analysis provided volumetric change detection over small, medium, large and recessed areas. Both the Sishen and Kolomela mines demonstrated height profile changes in each selected category. The last category of results focused on the SAR technology to measure within millimetre accuracy the subsidence and upliftment behaviour of surface areas over time. The Royal Bafokeng Platinum tailings pond area was measured using 74 TerraSAR-X scenes. The tailings wall area was confirmed as stable with natural subsidence that occurred in its surrounding area due to seasonal changes of the soil during rainy and dry periods. The Chuquicamata mine as a large open pit copper mine area was analysed using 52 TerraSAR-X scenes. The analysis demonstrated significant vertical surface movement over some of the dumping sites. It is the wish of the researcher that this dissertation and future research scholars will continue to contribute in this scientific field. These contributions can only assist the mining sector to continuously improve its mining operations as well as its monitoring of the primary as well as the secondary environmental impacts to ensure improved sustainability for the next generation.Environmental SciencesM. Sc. (Environmental Science

InSAR as a tool for monitoring hydropower projects: A review

This paper provides a review of using Interferometric Synthetic Aperture Radar (InSAR), a microwave remote sensing technique, for deformation monitoring of hydroelectric power projects, a critical infrastructure that requires consistent and reliable monitoring. Almost all major dams around the world were built for the generation of hydropower. InSAR can enhance dam safety by providing timely settlement measurements at high spatial-resolution. This paper provides a holistic view of different InSAR deformation monitoring techniques such as Differential Synthetic Aperture Radar Interferometry (DInSAR), Ground-Based Synthetic Aperture Radar (GBInSAR), Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR), Multi-Temporal Interferometric Synthetic Aperture Radar (MTInSAR), Quasi-Persistent Scatterer Interferometric Synthetic Aperture Radar (QPSInSAR) and Small BAseline Subset (SBAS). PSInSAR, GBInSAR, MTInSAR, and DInSAR techniques were quite commonly used for deformation studies. These studies demonstrate the advantage of InSAR-based techniques over other conventional methods, which are laborious, costly, and sometimes unachievable. InSAR technology is also favoured for its capability to provide monitoring data at all times of day or night, in all-weather conditions, and particularly for wide areas with mm-scale precision. However, the method also has some disadvantages, such as the maximum deformation rate that can be monitored, and the location for monitoring cannot be dictated. Through this review, we aim to popularize InSAR technology to monitor the deformation of dams, which can also be used as an early warning method to prevent any unprecedented catastrophe. This study also discusses some case studies from southern India to demonstrate the capabilities of InSAR to indirectly monitor dam health

Análise de subsidência em áreas urbanas : um estudo envolvendo a interferometria diferencial de imagens SAR em uma abordagem multitemporal

Orientadora: Profª. Drª. Regiane DalazoanaCoorientadoras: Profª. Drª. Cláudia Pereira Krueger e Profº. Drº. Laurent PolidoriTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Programa de Pós-Graduação em Ciências Geodésicas. Defesa : Curitiba, 14/08/2023Inclui referências: p. 111-124Resumo: Para compreender e monitorar adequadamente os riscos decorrentes de processos deformantes, como a subsidência, é fundamental identificá-los e avaliar sua magnitude de forma precisa. O uso difundido do GNSS permite uma avaliação geral dessas instabilidades por meio de posições absolutas ou medições contínuas dos pontos dentro das áreas afetadas. Além disso, a abordagem interferométrica de abordagem multi-temporal (MT-InSAR), como a técnica PSInSAR, possibilita o monitoramento e a detecção de pequenas variações no terreno causadas por movimentos da superfície, como deslizamentos de terra ou subsidência. Neste trabalho, os resultados do processamento interferométrico empregando a técnica PSInSAR foram analisados. Inicialmente, um estudo foi realizado em uma área com histórico de subsidência no bairro Pinheiro, em Maceió, Brasil, para verificar o processo de subsidência após um terremoto em 2018. Foram utilizados pacotes de processamento gratuito, como a integração SNAP-StaMPS. Em um segundo estudo, complementamos os resultados de uma análise de subsidência por meio de observações GPS realizadas no bairro Guabirotuba, em Curitiba (PR). O processamento PSInSAR foi aplicado a 77 imagens SAR da missão Sentinel-1A, adquiridas no modo descendente no período de 2016 a 2019. Os resultados obtidos no primeiro teste permitiram a detecção e mensuração da taxa de deslocamento na área estudada. No bairro Pinheiro, os processamentos foram capazes de identificar a subsidência de forma precisa durante e após o terremoto. A velocidade média de subsidência na direção Line-of-Sight foi classificada como lenta, enquanto nas áreas circundantes foi classificada como extremamente lenta. No bairro Guabirotuba, a subsidência detectada apresentou uma velocidade extremamente lenta, possivelmente devido às características geológicas do terreno ou a um deslocamento sazonal da região. Em suma, o uso da técnica PSInSAR revelou-se eficaz na detecção e monitoramento da subsidência em ambas as áreas de estudo. Os resultados obtidos contribuem para o entendimento dos processos deformantes e fornecem informações valiosas para a avaliação e o gerenciamento dos riscos associados. Com a continuidade desse tipo de pesquisa, será possível aprimorar ainda mais as técnicas de monitoramento e compreender melhor os fenômenos que afetam o terreno, possibilitando uma tomada de decisão mais informada e uma mitigação eficaz dos riscos.Abstract: To properly understand and monitor the risks arising from deformative processes such as subsidence, it is essential to identify them and assess their magnitude accurately. The widespread use of GNSS allows for a general evaluation of these instabilities through absolute positioning or continuous measurements of points within the affected areas. Additionally, the multi-temporal interferometric approaches (MT-InSAR), such as the PSInSAR technique, enable monitoring and detection of small variations in the terrain caused by surface movements, such as landslides or subsidence. In this study, the results of interferometric processing using the PSInSAR technique were analyzed. Initially, a study was conducted in an area with a history of subsidence in the Pinheiro neighborhood, Maceió, Brazil, to investigate the subsidence process following an earthquake in 2018. Free processing packages like SNAP-StaMPS were used. In a second study, we complemented the results of a subsidence analysis with GPS observations conducted in the Guabirotuba neighborhood, Curitiba (PR). The PSInSAR processing was applied to 77 SAR images from the Sentinel-1A mission, acquired in descending mode from 2016 to 2019. The obtained results allowed for the detection and measurement of the subsidence rate in the studied area. In the Pinheiro neighborhood, the processing was able to accurately identify subsidence during and after the earthquake. The average subsidence velocity in the Line-of- Sight direction was classified as slow, while in the surrounding areas, it was classified as extremely slow. In the Guabirotuba neighborhood, the detected subsidence exhibited an extremely slow velocity, possibly due to the geological characteristics of the terrain or seasonal displacement in the region. In summary, the use of the PSInSAR technique proved effective in detecting and monitoring subsidence in both study areas. The obtained results contribute to the understanding of deformative processes and provide valuable information for risk assessment and management. With the continuation of this type of research, it will be possible to further improve monitoring techniques and gain a better understanding of the phenomena affecting the terrain, enabling informed decision-making and effective risk mitigation

Insar measurements at high latitudes.

This thesis contributes towards understanding of Interferometric Synthetic Aperture Radar (InSAR) measurements at high latitudes. Luossavaara-Kiirunavaara Aktiebolag (LKAB) mining company, the sponsor of this Ph.D. research, intends to use the InSAR techniques for subsidence measurements around the Kiruna underground iron ore mine. The Kiruna underground iron ore mine is located in direct proximity to the city of Kiruna, with the active mining area currently about 1 km west of the city center (67°51'20" N, 20°13'30 E). At present LKAB is exploring the possibility of using InSAR measurements as an operational technique for subsidence measurements. High latitudes InSAR measurements are known to be particularly affected by long periods of ground snow cover that contributes to temporal de-correlation between subsequent radar images. The objectives of this Ph.D. research are (1) to quantify the seasonal effects in InSAR measurements and (2) to identify techniques to improve the high latitude InSAR measurements. In this research study, spatial coherence was used to quantify the seasonal effects in the Differential InSAR (DInSAR) measurements for Kiruna region. A comparison between Static Global Positioning System (Static-GPS) and Corner Reflector InSAR (CRInSAR) measurements were carried out to quantify the seasonal effects in CRInSAR measurements. Spatial ground deformation patterns were used to improve the DInSAR measurements. A theoretical analysis for compact active transponders (CAT) was carried out to improve the North-South InSAR measurements. DInSAR, CRInSAR and Coherent Target Monitoring (CTM) techniques were used to evaluate the applicability of InSAR techniques for high latitude mining induce deformation measurements. The results show seasonal variations in DInSAR, CTM and CRInSAR measurements. Furthermore, DInSAR measurements around the Kiruna iron ore mine can be improved up to sub-centimeter accuracies by using the spatial ground deformation patterns. Also, the compact active transponders identi ed as a possible candidate to improve the accuracy of the North-South InSAR measurements. It is concluded that, all InSAR techniques (DInSAR, CTM and CRInSAR) were affected by the winter snow condition, and only the summer (snow-free) months are suitable for ground deformation measurements. Moreover, the study shows that without the winter images still it is possible to achieve accurate CTM and CRInSAR time series estimations for Kiruna. The East-West vector is the least noisy deformation vector, and both East-West and vertical vectors can be used to determine the LKAB environmental criterion. At present, every year, LKAB is acquiring 45 Radarsat-2 images from three beam modes. However, this study shows that less than 35% of those data are useful for subsidence measurements

Synthetic aperture radar remote sensing for landfill monitoring

Despite today’s intensive efforts directed at the recycling and recovery of solid wastes, the controlled disposal of refuse into land remains an important and necessary means of effective waste management. The work presented in this thesis investigates the use of Synthetic Aperture Radar (SAR) data to monitor solid waste landfills. The end-users’ interests vary from detecting the presence of a landfill to more specifically monitoring on-site operations and environmental conditions. Following a general literature review on the application of Earth Observation data for landfill monitoring, the identified research objectives are to: 1) assess whether SAR data can support the identification of landfill sites by distinguishing them from other disturbed areas which present similar optical spectral signatures, and 2) assess the possibility of correlating SAR data with onsite operational procedures. Data acquired for the research are: ground observations and measurements examining the spatial, temporal and biophysical characteristics of a landfill that can influence SAR data; historical and new programmed SAR scenes obtained from the ESA ERS-1 and -2 satellites and from Envisat ASAR instrument; ground based SAR (GB-SAR) acquisitions; simulations based on the RT2 backscatter model; additional space-based and airborne optical data to support the analysis and discussion. The examination of both the SAR amplitude spatial structure and the temporal decorrelation of these sites shows that there are three key characteristics that can distinguish them from other disturbed areas with similar optical spectral signatures: the presence of anisotropic features that strongly affect the SAR backscatter; the fact that the coherence magnitude images of these sites are characterised by large decorrelated areas with transient attributes; and their distinctive positive topography. The analysis highlights that one single-polarisation acquisition can hardly provide correct land-cover information, and consequently knowledge on land-use. The research demonstrates the key value of merging together complementary information derived from both the space and time dimensions, achieving fairly accurate land-use classification results. The research also provides an appreciation of the applicability of the developed techniques in an operational framework. These can suffer a number of limitations if a landfill site is located in a particular environment, and/or if meteorological conditions can significantly affect the radar signal, and/or unusual landfilling procedures are applied by the operators. Concluding remarks on the end-users needs point out that there are a number of aspects, ranging from practical and managerial matters to legal and technical issues, that often discourage the utilisation of EO data by new potential users.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Remote Sensing and Geosciences for Archaeology

This book collects more than 20 papers, written by renowned experts and scientists from across the globe, that showcase the state-of-the-art and forefront research in archaeological remote sensing and the use of geoscientific techniques to investigate archaeological records and cultural heritage. Very high resolution satellite images from optical and radar space-borne sensors, airborne multi-spectral images, ground penetrating radar, terrestrial laser scanning, 3D modelling, Geographyc Information Systems (GIS) are among the techniques used in the archaeological studies published in this book. The reader can learn how to use these instruments and sensors, also in combination, to investigate cultural landscapes, discover new sites, reconstruct paleo-landscapes, augment the knowledge of monuments, and assess the condition of heritage at risk. Case studies scattered across Europe, Asia and America are presented: from the World UNESCO World Heritage Site of Lines and Geoglyphs of Nasca and Palpa to heritage under threat in the Middle East and North Africa, from coastal heritage in the intertidal flats of the German North Sea to Early and Neolithic settlements in Thessaly. Beginners will learn robust research methodologies and take inspiration; mature scholars will for sure derive inputs for new research and applications