Integrated satellite imagery and electrical resistivity analysis of underground mine-induced subsidence and associated risk assessment of Barapukuria coal mine, Bangladesh

This study addresses the critical issue of land subsidence in densely populated agriculture-based country, Bangladesh, focusing on the Barapukuria coal mine area. Our research employed time-series analysis of Landsat satellite imagery from 2005 to 2020, coupled with vertical electrical sounding resistivity methods. Through the false color composite image analysis in Earth Engine and GIS-based mapping, we quantified the areal extent of subsidence, and results were validated by field visits and cross-referencing with ESRI and dynamic world land use–land cover maps. Our study revealed a concerning trend of subsidence moving from west to east, towards the two nearby residential areas. Most importantly, the rate of areal extent of subsidence was alarming (17.4 acres per year), resulting in a cumulative loss of 205 acres since 2008. Linear regression predicts that this subsided area will double to around 405 acres by 2030, indicating significant risk to nearby communities. The trajectory of subsidence extent led us to examine the subsurface condition of nearby villages using calibrated vertical electrical sounding and borehole data. This revealed a higher resistivity in the northern area, indicating a future subsidence risk compared to the southern part. This was further confirmed by subsurface lithology, composed mainly of Holocene deposits containing clay, clayey sand, and sand. These layers, with their inherent instability and higher consolidation potential, exhibited higher resistivity and more prone to land subsidence. Overall, this study provides valuable insights for predicting subsidence, assessing associated risks, and guiding policy decisions to prevent future damage and facilitate community rehabilitation.