Abstract
The environmental impact assessment of underground mining usually includes the direct effects of exploitation. These are damage to rock mass and land subsidence. Continuous dewatering of the aquifer system is, however, necessary to carry out underground mining operations. Consequently, the drainage of the aquifer system is observed at a regional scale. The spatial extent of the phenomenon is typically much wider than the direct impact of the exploitation. The research presented was, therefore, aimed at evaluating both the direct and the indirect effects of underground mining. Firstly, the spatial extent of land subsidence was determined based on the Knothe theory. Secondly, underground mining-induced drainage of the aquifers was modeled. The 3D finite-difference hydrogeological model was constructed based on the conventional groundwater flow theory. The values of model hydrogeological parameters were determined based on literature and empirical data. These data were also used for model calibration. Finally, the results of the calculations were compared successfully with the field data. The research results presented indicate that underground mining’s indirect effects cover a much larger area than direct effects. Thus, underground mining requires a broader environmental assessment. Our results can, therefore, pave the way for more efficient management of groundwater considering underground mining.
Highlights
The environmental impacts of mining can occur through direct and indirect mining practices at local, regional, and global scales [1]
The groundwater pumping started in June 1976 and is continuously carried out in four drainage wells located in the central part of the mining area (Figure 3A,B)
In 2020, the area of the depression cone in the Middle Jurassic aquifer is about 6.7 times larger than the spatial extent of the land subsidence directly related to the mining operation
Summary
The environmental impacts of mining can occur through direct and indirect mining practices at local, regional, and global scales [1]. Development of the crack zone may facilitate the inflow of groundwater into post-mining voids, resulting in the rapid depletion of the overlying aquifers and the vanishing of surface watercourses [48,50] This effect can result in compressive strains occurrence that implies a reduction in the diameter of the original structural discontinuities of the rock mass. Much research has revealed that the values of these parameters may even be 100 times different from the initial values as the result of geomechanical changes in the rock mass [39,57,58] Such large variability in hydraulic conductivity can affect the results of computed groundwater head changes and should be considered in hydrogeological models [59].
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