Influence of coal mining on shallow groundwater environment response to coal mining and mine water ecological utilization analysis

The contradiction between coal and water is prominent in the upper and middle reaches of the Yellow River Basin, and coal mining activities has caused certain damage to groundwater environment in those areas. So the quantity and quality characteristics of mine water for the Yushenfu mining area in Yulin City of northern Shaanxi Province were analyzed to reveal the influence of coal mining on the groundwater environment, and the ecological utilization study of mine water was also carried out based on field investigation, data analysis and laboratory tests. The results show that the mine water content coefficient in the study area ranged from 0.23 to 2.28, with an average of 0.91. In 2020, the estimated mine drainage was as high as 4.70×10⁸ m³. The groundwater level in shallow buried mines decreased obviously affected by mining activities. The mine water quality of this area was poor, the COD, Na⁺, SO₄ ²⁻, TDS were the main factors that exceeded permitted levels, and therefore the drainage of mine water would pollute the groundwater environment. At present, the over-limit water quality index of shallow groundwater was mainly NO₃-N, which was significantly different from that of mine water, indicating that the quality of shallow groundwater in the study area was less affected by mining activities. The artificial mine water reinjection and mine water ecological irrigation were two important modes of mine water ecological utilization. The mine water reinjection had a good performance in removing of dissolved organic carbon and chroma, and the groundwater quality level meet the requirements of class III after mine water reinjection. The mine water of shallow buried mines had a good potential to be used for irrigation water for ecological restoration, but the mine water of mid-deep and deep-buried mines was not suitable as irrigation water. The results provide an important basis for water resources protection and ecological restoration in coal mining areas of western China.