Monitoring of Post-Mining Subsidence using Airborne and Terrestrial Laser Scanning Approach

Discontinuous deformations, such as sinkholes, pose significant challenges in post-mining areas due to their unpredictable nature and potential hazard to surface development and the safety of local communities. Therefore, monitoring the post-mining regions should be treated as a continuing task. This study addresses the ongoing problem of sinkhole formation in the former “Przyjaźń Narodów – Szyb Babina” (Babina) lignite mine located in the glaciotectonic region of Muskau Arch in western Poland. The research uses airborne and terrestrial laser scanning methods to identify and monitor discontinuous deformations, focusing on a newly discovered sinkhole. The methodology involves differential analysis of Digital Elevation Models (DEMs) and their derivatives obtained from airborne laser scanning (ALS) and periodic terrestrial laser scanning (TLS) measurements. The results of ALS DEM analysis allowed the successful identification of 75 confirmed sinkholes, the largest measuring 12.8 m in diameter and 4.8 m deep. Whereas, differential DEM analysis indicated new sinkholes that developed between 2011 and 2020 in the area of shallow underground mining. Two-year TLS monitoring of the new sinkhole showed no progression in its dimensions. However, localised erosion processes associated with water transport were detected. The study shows that sinkhole formation processes are active 5 decades after the end of mining and highlights the importance of continuous monitoring of post-mining areas with advanced laser scanning methodss.