A self-heating intensity index (SHII) based on the highest (pixel max.) and lowest (pixel min.) values taken from satellite thermal maps of burning coal waste dumps are proposed. The index enables the classification of such fires in Ukrainian- and Polish coal waste dumps. Both in Ukraine and in Poland, varying thermal intensities during 1985–2019 are revealed, using the SHII and following thermal intensity threshold values, namely, extreme thermal activity (> 7), advanced (3–7), moderate (3–1.5), initial (1.5–1), no activity (< 1). The SHII shows decreasing thermal activity in the selected Ukrainian coal waste dumps during 2017–2019. It aids in reconstructing the thermal history of the dumps. Analysis of satellite images revealed a large number of burning coal waste dumps in the Donetsk Coal Basin (Ukraine) with high thermal activity. Such burning likely reflects large amounts of organic matter and sulphides in the dumped material subjected to self-heating and self-burning processes, lack of compaction of the coal waste and/or high methane contents. Comparison of SHII values calculated from satellite- and drone thermal-camera images were compared to show that SHII from drone thermal images have much higher values than those from satellite images; the former have better resolution. Thus, SHII from Landsat- and drone images should be used separately in dump heating studies.

Coal-waste dumps are an integral part of the environment and shape the landscape of coal basins. This study aimed to present an analysis of environmental changes in terms of land use and changes in vegetation on self-heating coal-waste dumps of different ages. Spatial and temporal analyses of land relief and land cover in the area of the investigated coal-waste dumps were performed. The investigated areas differed in size, shape, management, and land cover. Thermally active zones were identified. The results showed that the species composition of the flora is diverse, but representatives of the Asteraceae family dominate on both dumps. The diversity of flora in the investigated dumps depends on the presence of mosaic- and microhabitats (often of an extreme nature) and the nature of the vegetation in the surroundings, which is manifested by the participation of socioecological groups of flora. The pace and dynamics of succession on burning coal-waste dumps depends on the stage of the fire, the topography, and the nature of the substrate. The investigated changes in the elements of the environment are important from the point of view of application research and monitoring of postindustrial areas, which may allow for the optimal management of postmining dumps.

Many temporary and permanent reservoirs of water occur on or near coal-waste dumps in the Lower- and Upper Silesian Coal Basins (Poland). Little or nothing is known of the degree to which their water chemistry might reflect (i) reservoir type, i.e., whether permanent or temporary, (ii) level of coal-waste thermal activity, i.e., whether inactive or self-heating or burnt-out or (iii) region, i.e., whether the dumps are in Upper- or Lower Silesia. To provide some answers, concentrations of selected ions (NH₄⁺, HCO₃⁻, F⁻, Cl⁻, Br⁻, NO₂⁻, NO₃⁻, PO₄³⁻,SO₄²⁻) were determined by ion chromatography and of nineteen elements (Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, P, Pb, S, Si, Sr, Zn) by inductively coupled plasma mass spectrometry (ICP-MS). The data allow a number of the following observations. When permanent reservoirs are considered, there is a clear relationship between concentrations of ions and major and trace elements and dump thermal activity. The highest concentrations occur where the thermal activity is high as inorganic components are transformed into more water-soluble forms. As dump thermal activity shows a regional pattern, it follows also that elemental and ion concentrations in the dump waters show significant regional differences. In temporary reservoirs, concentrations of ions and major and trace elements are much lower and any correlations between components less significant than in the permanent reservoirs; these reservoirs exist for too short a time for any balance between coal waste- and water components to be established.