Predicting water level rises and their effects on surrounding karst water in an abandoned mine in Shandong, China

Abstract

After a mine is closed, dewatering is discontinued, this may lead to a large increase in groundwater levels and deterioration in water quality, which will threaten the safety of surrounding water supplies. To address this problem, these effects were investigated using the Shanjialin Coal Mine, in Shandong Province, China, as a case study. Following the mine closure, five water quality monitoring points showed that sulfate and total hardness in the mine water were 529 and 685 mg/L, exceeding the allowable groundwater environmental quality standards by 2.1 times and 5.2 times, respectively. This will lead to pollution of the surrounding karst aquifer. A numerical groundwater model was established to simulate the water level rise after the mine closed. The simulation results showed that the mine water level will equal the karst aquifer water level seven years after closure. If the water level in the mine continues to rise above the level of the karst aquifer, it may lead to a deterioration in the karst water quality. Therefore, the mine water level should remain less than 15 m.