ABSTRACT
Sinkholes can continue to develop in post-mining areas decades after mining activities have ended, posing ongoing hazard. This study aimed to assess ground movements in potentially sinkhole-prone areas in the former “Babina” brown coal mine (West Poland), closed over 50 years ago. Five research levelling networks were set-up and 6 levelling campaigns were conducted between September 2020 and September 2024. The geodetic surveys confirmed the presence of continuing ground deformations in selected parts of the study area. The greatest registered subsidence amounted to -24.0 mm. Based on a digital terrain model differentiation approach and in-situ verification 230 sinkholes were identified with diameters ranging from 2.7 to 11.2 m. Next, a geodatabase integrating sinkhole data, digitized mining maps, gravity surveys, and geodetic monitoring results was developed and used to determine spatial congruence between underground voids and sinkholes. The existence of subsurface disturbance (underground corridors) in the analysed sinkhole locations was confirmed by the observed gravimetric anomalies. These findings highlight that the risk of sinkhole formation can persist for decades after mine closure. The integrated monitoring approach proved effective in identifying subsidence risk zones, particularly in vegetated areas, where remote sensing methods are less applicable.
