Classification of fires in coal waste dumps based on Landsat,Aster thermal bands and thermal camera in Polish and Ukrainian mining regions

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.

A drone‑and feld‑based investigation of the land degradation and soil erosion at an opencast coal mine dump after 5 years’evolution of natural processes

Opencast coal mining has a large impact on the land surface,both at the mining pits themselves and at waste sites.After artifcial management is stopped,a reclaimed opencast coal mine dump is afected by wind and water erosion from natural processes,resulting in land degradation and even safety incidents.In this paper,the soil erosion and land degradation after 5 years of such natural processes,at the Xilinhot opencast coal mine dump in Inner Mongolia,were investigated.A multisource data acquisition method was applied:the vegetation fraction coverage(VFC)was extracted from GF-1 satellite imagery,high-precision terrain characteristics and the location and degree of soil erosion were obtained using a drone,and the physical properties of the topsoil were obtained by feld sampling.On this basis,the degree and spatial distribution of erosion cracks were identifed,and the causes of soil erosion and land degradation were analyzed using the geographical detector.The results show that(1)multi-source data acquisition method can provide efective basic data for the quantitative evaluation of the ecological environment at dumps,and(2)slope aspect and VFC are the main factors afecting the degree of degradation and soil erosion.Based on above analysis,several countermeasures are proposed to mitigate land degradation:(1)The windward slope be designed to imitate the natural landform.(2)Reasonable engineering measures should be applied at the slope to restrain soil erosion.(3)The Pioneer plants should be widely planted on the platform at the early stage of reclamation.