Satellite-based, integrated environmental monitoring of mine sites: an example from the Roşia Poieni copper mine, Romania

Mining operations produce vast amounts of waste, posing critical geotechnical, environmental, and social risks. The EU Horizon-funded Multiscale Observation Services for Mining-Related Deposits (MOSMIN) project addresses these challenges by developing integrated Earth Observation (EO)-based services that combine satellite, uncrewed aerial vehicle (UAV), and in-situ data. These services aim to deliver innovative multi-scale, multi-source solutions for enhanced environmental and geotechnical monitoring as well as valorisation, aligning with environmental, social, and governance (ESG) goals in the raw materials industry. MOSMIN’s case studies across diverse mining sites demonstrate the real-world application and benefits of these services.

We apply this integrated framework at the Roșia Poieni open-pit porphyry copper mine in Romania to monitor its environmental impact and to support the development of effective remediation strategies. We use long-term satellite archives for temporal analysis of large-scale impacts, augmented by high-resolution UAV and in-situ data for localized insights and validation. Ground-truthed hyperspectral satellite (e.g. EnMAP) data allow us to map the mineral composition of waste rocks, identifying potential acid-generating and buffering materials. Multispectral Sentinel-2 and Landsat data enable monitoring of vegetation health and water quality over time, offering insights into the downstream effects of acid mine drainage (AMD). We then conduct supervised mapping of hydrogeochemical properties and AMD-associated minerals in sediments based on UAV hyperspectral data in areas of interest identified in the satellite data. Sentinel-1 InSAR and UAV-based topographic data provide displacement susceptibility maps.

Our results highlight the substantial environmental impacts of mining at Roșia Poieni. The waste rock dumps are predominantly characterized by argillic alteration, interspersed with potassic and phyllic alteration zones enriched in sulfides, which are potential sources of AMD. Secondary iron minerals spectrally identified within the dumps and downstream sediments provide clear evidence of AMD, as do elevated AMWI (Acid Mine Water Index) values in the water runoff, which show strong correlations with measured dissolved iron concentrations and pH levels. A 30-year Fourier-based harmonic analysis of vegetation indices reveals a progressive decline in vegetation health around the tailings pond and waste rock dumps, largely driven by mine expansion. In contrast, areas northwest of the open pit and downstream of the tailings dam show net vegetation recovery, suggesting effective reclamation measures. InSAR-derived displacement data highlight accumulated ground movements of up to 200 mm per year in parts of the northern waste rock dump, raising concerns about geotechnical stability.

This case study highlights the value of integrated EO-based monitoring for understanding mining’s environmental impacts. The insights gained enable informed decision-making, support targeted remediation of existing issues, and facilitate mitigation measures to prevent future harm, through collaboration with local communities, governments, and the mine operator.