Transformation processes in lignite post-mining landscape – erosion of anthropogenic formations in the former “Przyjazn Narodow – Szyb Babina” mine (Poland).

Mining of minerals impacts all components of the ecosystem and the post-mining environment should be continuously monitored to control the quality and efficiency of reclamation procedures. In the past post-mining areas often did not undergo the full process of reclamation and were left unmonitored. This study was aimed at analysis of surface (gully) erosion in an abandoned lignite post-mining area located in the present cross border German-Polish Geopark Muskau Arch. For this purpose, low-cost unmanned aerial vehicle (UAV) photogrammetry to acquire data describing the surface condition of partly rehabilitated dump sites and subsequently a digital elevation model (DEM) of difference (DoD) approach to analyse quantitatively elevation change were applied. The results based on processing of data from four UAV missions carried out between Spring 2020 and Autumn 2021 (18 months) allowed to determine the elevation models with high accuracy (±0.02 – ±0.04 m) and develop differential elevation models for the estimation of material movement and surface change in three selected gullies. All of the study sites were subjected to surface erosion probably due to the effect of rainfall that caused natural landscaping of the area. The greatest observed elevation changes connected with loss of material in research crosssections reached 0.9 m. The UAV based data calculation of the DEM of difference has proved a time efficient and accurate method for analysis of elevation change in post-mining areas subjected to surface erosion. For the best results it is recommended to plan the UAV flight missions when the sun is at its highest or in cloudy weather to minimise the effect of sunshading on the quality of the generated DEMs. A further study to correlate material movement with precipitation records is planned. [ABSTRACT FROM AUTHOR]