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Application of synthetic aperture radar interferometry to monitor surface deformations of the Trans-European Transport Network (TEN-T) - a case study of the motorways crossing areas of mining operations in the Upper Silesian coal basin, Poland

Stawinoga Mariusz, Pindel Tomasz, Smoliński Adam

Journal of Sustainable Mining

2021

Vol. 20, iss. 3

136--143

Underground hard coal mining causes surface deformations. When the mining operations are conducted beneath linear objects, such as motorways, there is a risk of deformations of the axis of the road and its horizontal and vertical alignment (additional bends and vertical curvatures, longitudinal inclinations, deformations of cross-sections). In the areas subjected to mining operations, mining plants conduct geodetic monitoring. Due to their labour intensity and costs, geodetic measurements are usually made only a few times a year. The article discusses the possibility of applying Interferometric Synthetic Aperture Radar (InSAR) to monitor the subsidence of the vertical alignment of motorways caused by mining operations and its advantages and disadvantages compared to the currently used methods of geodetic measurements. The tests were conducted in two sections of motorways within the Upper Silesian Coal Basin (Poland) in the areas of intensive hard coal mining operations. Radar imaging of the surface made by the European Space Agency's (ESA) satellite Sentinel-1 equipped with the Synthetic Aperture Radar (SAR) was used.

Slope movement monitoring through a combination of IoT and InSAR

Guilhot T., Martinez del Hoyo T., Bartoli A., Ramakrishnan P., Leemans G., Houtepen M., Salzer J., Metzger J. S., Maknavicius G.

Gospodarka Wodna

2021

Nr 9

35--40

Tailings dams are critical, complex infrastructures that result particularly challenging to secure. Complex systems involving a variety of physical and digital devices have recently been used, but an optimized solution remains difficult to find due to the dimensions and complexity of the areas to be monitored. The use of siloed processes to manage such infrastructures is generally not a practical and cost-effective process. New combinations of technologies must be explored to provide optimum solutions. This paper presents a commercial, cost-effective method to accurately monitor slope movements. The combination of a network of surface sensors with satellite radar data is proposed. The Internet of Things monitoring system is composed of several distributed data collection points, used in combination with periodic InSAR studies. The correlation of both data sets is demonstrated in a testbed in which slope failure events are detected and long-term drifts confirmed. This study has been performed in a real-life testbed and two events have been detected. In the first slope failure event, the data is correlated between all technologies involved: same direction, with different orders of magnitude consistent with the sensors’ location. In the other event, some technologies have detected the event whilst the tiltmeters have demonstrated that the structure had not been affected.

Zapory zbiorników wodnych oraz inne budowle ziemne są ważną i złożoną infrastrukturą, której zapewnienie trwałości i poprawnego funkcjonowania stanowi szczególne wyzwanie. Ostatnio, do oceny trwałości skap tych budowli oraz zboczy naturalnych, próbuje się stosować złożone systemy obejmujące różne fizyczne i cyfrowe urządzenia, ale wciąż, ze względu na wymiary i złożoność obszarów, które mają być objęte monitoringiem, potrzebne jest znalezienie rozwiązania optymalnego. Wykorzystanie „procesów silosowych”10) do zarządzania taką infrastrukturą jest na ogół procesem niepraktycznym i nieopłacalnym. Należy więc zbadać nowe kombinacje technologii, aby zapewnić optymalne rozwiązania. W artykule przedstawiono komercyjną, efektywną kosztowo metodę dokładnego monitorowania ruchów skarp. Zaproponowano połączenie sieci czujników powierzchniowych z satelitarnymi danymi radarowymi. System monitoringu oparty na Internecie Rzeczy (Internet of Things – IoT) składa się z kilku rozproszonych punktów zbierania danych, wykorzystywanych w połączeniu z okresowymi pomiarami z systemu satelitarnej interferometrii radarowej (Interferometric Synthetic Aperture Radar – InSAR). Korelacja obu zestawów danych jest wyświetlana na stanowisku badawczym, w którym wykrywane są zdarzenia awarii zbocza i potwierdzane długoterminowe ruchy osuwiskowe. Badanie to zostało przeprowadzone na rzeczywistym stanowisku badawczym, gdzie wykryto dwa zdarzenia. W pierwszym przypadku uszkodzenia zbocza dane są skorelowane pomiędzy wszystkimi zaangażowanymi technologiami: ten sam kierunek, różne rzędy wielkości zgodne z lokalizacją czujników. W drugim przypadku, niektóre technologie wykryły zdarzenie, podczas gdy pochyłomierze wykazały, że konstrukcja nie została naruszona.

Introduction to interferometry processing with Doris: the Delft object-oriented radar interferometric software

Kniotek M., Mirek K.

Geology, Geophysics and Environment

2012

Vol. 38, no. 4

480--481

Interferometrie synthetic aperture radar (InSAR) is a powerful tool for mapping the Earth's land, ice and even the sea surface topography. It is based on processing of the pair of images to map out the differences in the reflected signals over the area (typically 100 km x 100 km). By bouncing signals from a radar satellite off the ground in successive orbits and looking at the differences between the images, interferometrie synthetic aperture radar can detect small differences in the distance between its position and the ground as the land surface moves - whether up or down. A digital SAR image can be seen as a mosaic of pixels. Each pixel gives a complex number that carries amplitude and phase information about the microwave field backscattered by all the scatterers (such as rocks, buildings, vegetation) within the corresponding resolution cell projected on the ground. The amplitude depends on the roughness and typically, exposed rocks and urban areas show strong amplitudes, whereas smooth flat surfaces (like quiet water basins) show low amplitudes. The phase is directly linked to the distance between the observed terrain and the satellite sensor. By calculating the differences in phases (interferogram) between two sets of data, one can determine ground displacements that have occurred in the time between the data acquisitions. One of the popular open source and free program called Doris (The Delft object-oriented Radar Interferometrie software) is developed to process data obtained from SAR systems. Doris basic input are SLC (Single Look Complex) images. Due to modular structure of program (processing is performed in steps/blocks), it is possible to write own steps of processing the data. Program is distributed with some helpful scripts and additional programs developed by community, which are compatible and ready to use with Doris.On every step of processing could be used other programs to: improve attributes of data (e.g. extra filtering), plot charts to check processed data or draw a maps. There are many possibilities for scripts wrote in Matlab or similar programs. SAGA GIS or GMT (The Generic Mapping Tools) could be used to view images or merge parts of them. All the time new programs are being developed ,which may be used with Doris or its result files. There are few other programs developed for InSAR processing like ROI_PAC or PHOTOMOD Radar, but in this article processing only in Doris is presented.The processing is not simple and may take few hours. Processing was made using data from European Space Agency before and after earthquake in Bam (Iran). At the beginning of processing, data need to be read and attached with orbits of satellite from day, when images were taken. In next step data could be connected with Digital Elevation Model (DEM) and be resampled if needed. Next, master and slave images are computed to take offsets between images. After this interferogram is created. From interferogram reference phase and reference DEM are being subtracted. At the end are being created unwrapped interferogram, coherence map and geo-coded interferogram, which is presented in geographical known reference system. Obtained products from Doris like unwrapped phase map could be helpful in earth science. Maps of terrain after unwrapping shows the terrain deformation with high accuracy of cm in resulution. The best results are shown using images which are taken before and after earthquake, but this is not the only use. Here should be again mentioned that data could be obtained even at night and through the clouds or snow caps, which cause problems in some areas of Earth. Plenty of data needed to interferometry processing is available for free.