The theme of the internship was directly connected with the grant of the European Space Agency: „Application of InSAR to Model Compaction of the Aquifer System and Movement of the Land Surface in Abandoned Mines” (Cosmo-SkyMed Project no. 65954), the head of which is Artur Guzy, M.Sc., Eng.
The degradation of rock mass and the occurrence of land subsidence or even sinkholes is one of the negative effects of underground mining. Such phenomena could damage infrastructure and threaten residents of altered regions. However, underground mining typically requires deep drainage of rock layers via pumping. The original hydrogeological conditions of the rock mass are therefore affected. As a result, due to the change in the groundwater levels and the decrease in the hydrostatic pressure, the aquifer system is depleted and rock mass is additionally compacted. However, with the closure of the mine by flooding, the aquifer system is beginning to be restored. The rock mass is re-filled with groundwater as a result, and uplifts occur on the land surface. However, the fluctuation and rapid flow of groundwater related to the flooding of the mine can also lead to rock mass suffocation and the formation of sinkholes.
Hard coal mining in Europe has a long tradition and goes back to the beginning of the industrial revolution. Coal mines were mainly located in the United Kingdom, Germany, Belgium, the Netherlands and Spain. Hard coal is still being mined in Poland.
Since many of Europe's underground mines have been or will soon be closed, the management of environmental risks during and after the closure of underground mines is an important issue. The European Commission is putting pressure on the authorities to take measures to mitigate the negative environmental impacts of the European raw material sector in the context of environmental protection. Consequently, the objective of the proposed project is to develop an environmental risk management methodology that considers sustainable mine closures in terms of land surface displacements.
The research will be carried out in the Asturian Coal Basin, Spain, in the area of underground hard coal mines closed by the flooding. Land surface displacements before the mine flooding process will be determined based on the InSAR satellite radar interferometry. However, immediately after the closure of the mines and for several years after the start of the process, land surface displacement will also be determined. COSMO-SkyMed data should be processed using multi-temporal time series techniques for this purpose.
Based on mining, geological and hydrogeological data, the physics of the rock mass decompression phenomenon will be recognized in conjunction with the InSAR data. Between the commencement of the mine flooding process and the occurrence of the land surface uplift, the time-lag will be determined. The overall dynamics of land surface displacements accompanying the flooding process of the underground hard coal mine will be determined due to the long measurement period.
The results of the research will contribute to a better understanding of the phenomenon of rock mass decompression in terms of underground mining. The research will contribute to the environmental assessment of the process of sustainable closure of underground mines.
The project will be part of the research grant entitled "Modeling of land surface movements due to rock mass drainage" funded by the National Science Center in Poland (Preludium Grant no. 2019/33/N/ST10/00724).
