The impact of precipitation on the groundwater of coal waste dump

The aim of the study was to assess the effect of climate change, mainly higher and lower precipitation, on the intensity of the impact of a coal waste dump on groundwater. The analysis used meteorological data for the Katowice region in 2002-2020 as well as data on the height of the groundwater table in the vicinity of the coal waste dump, and data on physicochemical parameters and chemical composition of groundwater in 2004-2020. Based on the analyses, it was found that the periods of drought in the Silesian Voivodeship, located in the south of Poland, occurred mainly in spring, while periods of excessive short-term rainfall in summer. The period of excessive annual precipitation occurred between 2007 and 2010, followed by a long period of dry or very dry years that lasted until 2016. During the period of excess annual precipitation, the leachate from the waste dump caused a decrease in the pH of groundwater from ca. 5 to 2.50, while an increase in electrolytic conductivity (EC) and the concentration of sulphates and zinc from ca. 1300 ms/cm, 100 mg/L, 5 mg/L to 5100 ms/cm, 3890 mg/L, 18.5 mg/L, respectively.