Development and Establishment of Calibration and Validation Sites for Radar Interferometric Analyses (InSAR) for Monitoring Ground Movement caused by Mine Water Rebound during the Post-Mining Era

Author: Dipl.-Ing. Volker Spreckels, RAG Aktiengesellschaft, Essen/Germany
DOI: 10.66356/mrg.2026.03.03.ENDECVS

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For several years now, satellite-based radar interferometry (InSAR) have been establishing themselves in day-to-day operations for the large-scale monitoring of ground movements in areas of both active and decommissioned mineral extraction. The combination of remote sensing techniques, such as satellite navigation (global satellite navigation system, GNSS) and interferometric synthetic aperture radar (InSAR), with traditional terrestrial surveying methods such as levelling and tacheometry holds great potential for reducing the time and labour-intensive terrestrial surveying to the absolute minimum required. During the transitional period required for this system conversion, these new methods must be examined and tested for their suitability, quality and robustness in order to be recognised and approved for use in mining documentation or within the framework of regulatory requirements. For these tests, RAG Aktiengesell­schaft (RAG), Essen/Germany, has designed novel calibration and validation (Cal/Val) fields for radar interferometric analyses (InSAR test fields), which were established from 2021 onwards in the former German hard coal mining areas in the Ruhr region of North Rhine-Westphalia with the support of the City of Essen, and in 2026 with the support of the State Surveying Authority in Saarland. This article traces the development from the first corner reflector sites used in research projects in 2006 to the current InSAR test fields based on multi-sensor reference stations (MSST) operated by RAG.