In this interdisciplinary project, which began in 2020, potential hazards in selected German coal-mining regions (Saarland, Ibbenbüren, the Ruhr area) that can be attributed to rising mine water levels are being investigated in collaboration with industry partners as well as geodesists, geomechanics experts, geophysicists, and geologists. Participants include KIT (Institute of Applied Geosciences, with the departments of Structural Geology & Tectonics and Technical Petrophysics, the Karlsruhe Geodetic Institute), Deutsche Montan Technologie GmbH & Co. KG, the European Institute for Energy Research (EIFER), the Geological Survey of North Rhine-Westphalia, Ruhr University Bochum (Chair of Geophysics), Piewak & Partner GmbH, and Alber Geomechanik.
The FloodRisk project is funded by the Federal Ministry of Education and Research (BMBF) as part of the funding initiative “Early Detection of Earthquakes and Their Consequences.” It is part of the BMBF’s specialized program “Geoscience for Sustainability” (GEO:N), which focuses on terrestrial and marine geoscientific research as well as Earth observation. GEO:N is part of the framework program “Research for Sustainable Development” (FONA).
The background of the project is that production in Germany’s coal-mining regions has been discontinued (Saarland in 2012, Ibbenbüren and the Ruhr region in 2018). During active mining operations, water had to be continuously pumped out of the mines, which incurred significant costs. On the other hand, shutting down the pumps would lead to the flooding of the mines and could have potentially undesirable consequences:

1. Damage to infrastructure due to heterogeneous ground uplift
2. Seismic activity caused by stress changes resulting from increasing pore pressure and the reactivation of faults
3. Groundwater contamination from polluted mine water

The Geodetic Institute’s role in the project was to determine displacements of the Earth’s surface using radar interferometry (InSAR). In particular, advanced InSAR methods were developed that can be applied in areas with temporally and spatially inhomogeneous deformation. In combination with geophysical, geomechanical, geological, and hydrological data, this enabled a better understanding of the processes caused by mine flooding. The research highlights of FloodRisk are the following results:

• Post-mining microseismicity is focused in pillar areas below the mine panels.
• Gas-monitoring with commercial and newly developed sensors shows temporally variable and anomalous outgassing into soil (Ruhr).
• InSAR data give a detailed picture of the codevelopment of mine water and surface displacements at Heinrich-Robert (Ruhr) and at Ibbenbüren (Ostfeld).

The Geodetic Institute collaborated with various partners who provided essential data for the project, notably RAG AG, DMT GmbH & Co. KG, and the Arnsberg District Government.