Application of MODFLOW usingTMR and discrete-step modification of hydraulic properties to simulate the hydrogeologic impact of longwall mining subsidence on overlying shallow aquifers

摘要

We apply Groundwater Vistas ? MODFLOW to model hydrologic impacts due to longwall subsidence in the shallow aquifer zone above a 220-m deep mine. Steep spatial and temporal changes are handled using TMR, zooming a transient local model (146,624 cells, 7.3 km~2) from a steady-state regional model (34,200 cells, 53 km~2). Because MODFLOW cannot handle run-time hydraulic property changes, we approximate the mine advance in discrete steps, modifying subsidence-altered property values in discrete stress zones. Simulated potentiometric responses in the demonstration model were similar to observed behavior but further calibration is needed.