Abstract:
Land subsidence resulting from groundwater extraction in mining operations can significantly affect water resource management and regulatory permitting. However, subsidence is frequently neglected in groundwater models supporting mine permit applications, potentially leading to underestimation of environmental impacts and operational challenges. This work evaluates the importance of incorporating subsidence mechanisms in groundwater modeling for mining dewatering projects through a comparative analysis of coupled groundwater-subsidence modeling versus groundwater-only simulation.
Subsidence following groundwater extractions occurs through elastic and inelastic aquifer compaction, depressurization-driven deformation, and changes in aquifer storage properties. We present a methodology for implementing subsidence in a three-dimensional groundwater model and provide an overview of subsidence capabilities using MODFLOW 6 [1] with the CSUB package [2]. The approach was applied to an idealized mine site, which includes boundary conditions observed in real mining environments, such as pumping, open pit development, adjacent agricultural activities and re-infiltration of produced groundwater via rapid infiltration basins (RIBs).
A three-dimensional groundwater model was developed with detailed stratigraphic layering to capture subsidence processes. Simulations were conducted under two scenarios: (1) coupled groundwater-subsidence modeling and (2) groundwater-only modeling without subsidence. Results demonstrate that incorporating subsidence significantly affects predicted surface deformation patterns, extent of drawdown influence, and magnitude of inflow. Additional impacts were observed on aquifer storage behavior, groundwater recovery dynamics, and assessment of water supply availability for mine processing operations. The analysis reveals that neglecting subsidence in groundwater models can lead to substantial errors in predictions relevant to both permitting decisions and operational planning. This work provides guidance for determining when subsidence should be incorporated in mining groundwater models and demonstrates practical implementation approaches for regulatory applications.
Presenter:
- Aya Mohamed | Consultant | SRK USA (Denver)
Co-Authors:
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