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1. Introduction
In operational mines, groundwater flooding of the working area is prevented by continuous pumping operations. However, once this pumping ceases, when a mine is abandoned, the groundwater level in the mine begins to rise again-a phenomenon called “groundwater rebound.” When this phenomenon occurs, groundwater either gradually flows back into the underground voids that were generated, due to mining activities or flows back into the strata near the mine. As a result, the groundwater level rises up to the groundwater discharge point; this is the level above which groundwater flowing into the mine flows back out to the surface or into surrounding aquifers, and is typically associated with mines because of artificial structures, such as shafts or drifts, built for mining activities.
Predicting the groundwater rebound phenomenon in a mine area is important for two reasons. First, a plan for draining the groundwater flowing into the pit can be established based on this prediction. Second, in an abandoned mine, this prediction can be utilized to prevent the surrounding environment (water and soil) from being polluted by acid mine drainage. There have been many studies on the assessment and prevention of environmental pollution due to acid mine drainage [1,2,3]. In particular, through prediction of the groundwater rebound phenomenon, we can forecast when groundwater that has flowed into a mining void after mine abandonment will fill the void and flow out and where this flow will occur. The combination of these predictions with mine drainage quality prediction technology enables the comprehensive assessment of changes in water quality resulting from mine outflow [4].
The quantitative information provided by mine groundwater rebound prediction technology makes it one of several important technologies for preventing mine-associated damage in areas with abandoned mines. Many case studies have been reported that consider the development and field application of models for groundwater rebound prediction. Toran and Bradbury [5] analyzed groundwater rebound in the vicinity of an abandoned lead and zinc mine using the MODFLOW model (United States Geological Survey, Virginia, United States), a representative finite difference groundwater flow model based on the Darcian groundwater flow equation [6]. Similarly, Sherwood [7] applied the MODFLOW model to predict the groundwater rebound associated with a large-scale coal field in the United Kingdom. Huisamen and Wolkersdorfer [8]...