Mapping alluvial mine dynamics in the Atewa landscape in Ghana using Geographic Object-Based Image Analysis (GEOBIA) and GIS

Abstract

The Atewa Range Forest Reserve (ARFR) in Ghana, a key biodiversity hotspot, is increasingly impacted by alluvial gold mining, which has been expanding in the region. However, limited research has focused on mining activities within the forest reserve or their proximity to river bodies. This study used high-resolution PlanetScope satellite imagery (2018–2023) and Geographic Object-Based Image Analysis (GEOBIA) to monitor mining activities and land use changes in the Atewa landscape. Post-classification change detection was used to determine land use land cover (LULC) classes that transitioned to alluvial mines while assessing post-mine vegetation recovery. Buffer analysis was used to examine the distance between mines and the forest reserve as well as water channels. Findings revealed an annual increase in mining activities at a change rate of 12.3% between 2018 and 2023, with significant vegetation conversion in the Atewa landscape. Mining exhibited a more irregular pattern in the forest reserve, with a rate of change of − 21.4%. The buffer analysis showed that a significant portion of mining occurred within 100 m of river channels, with at least 49.7% of the mined area annually falling within this zone. The buffer analysis also indicated that at least 0.7% of mining activities in the landscape were within the 100 m buffer around the ARFR. The study highlights the increasing threat of mining to the ARFR and the importance of monitoring these impacts on the forest and surrounding ecosystems.