Assessment of the Impact of the Spatial Extent of Land Subsidence and Aquifer System Drainage Induced by Underground Mining

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.

Land Subsidence Estimation for Aquifer Drainage Induced by Underground Mining

“…Figure 3. Schematic cross-section of geological strata and aquifer system in the area of interest, modified after [67,146]. The location of the cross-section is depicted in Figure 2.…”

“…Nonetheless, in many cases, even after the closure of mining operations, mine drainage maintenance is still required for safety reasons [66]. Due to the long-life cycle of underground mines, which can range from a few to several dozen years, the volume of groundwater pumped out of the rock mass is significant and, in many cases, exceeds billions of m 3 [67]. Such a substantial volume of groundwater withdrawn and a long-term process of mining-induced drainage results in a permanent change in the aquifer system's hydraulic conductivity and storage properties.…”

“…Such a substantial volume of groundwater withdrawn and a long-term process of mining-induced drainage results in a permanent change in the aquifer system's hydraulic conductivity and storage properties. Therefore, a decrease in hydrostatic pressure is observed at the large-scale depression cone [67,68]. The decrease in the groundwater head causes consolidation and compaction of the drained aquifer and the propagation of rock mass deformation to the terrain surface [25,69].…”

“…The spatial extent of the depression cone, and thus the area of land subsidence caused by aquifer drainage, is generally much larger than the direct impact of underground mining [67,68,70]. As a result, groundwater-related land subsidence frequently extends beyond mining boundaries [70].…”

On assessing the sustainable development of industrial regions results

“…The importance of environmental factors in assessing the results of sustainable development of industrial regions, repeatedly noted by the authors [11; 15], is confirmed by an increasing number of research on this topic. The set of environmental indicators depends on the objectives of the research and usually includes data on the amount of emissions and discharges of pollutants, state of soils and surface waters of the region of presence, air pollution, landscape transformation [16][17][18]. Obviously, the emergence and development of industrial clusters is based on the systemic change in the environment.…”