DETECTING GALAMSEY ACTIVITIES IN GHANA, WEST AFRICA USING REMOTE SENSING TECHNIQUES AND LANDSAT IMAGERY

The Government of Ghana is concerned with environmental and human health problems stemming from illegal gold mining activities, locally known as galamseys. To combat these illegal mining operations, the government has already invested millions in drone technology. Satellite remote sensing can provide a unique, cost effective opportunity for the government to survey large areas of land around Ghana for illicit mines. This study was focused on the Ghanaian towns of Asiakwa and Pampetia, which have both experienced illegal gold mining activities. In this study, potential use of Landsat (7 and 8) data in detecting these mines, in particular distinguishing them from other types of land use, was assessed using Normalized Difference Vegetation Index (NDVI), Tasseled Cap transformation, and supervised classification. The Landsat imagery was processed and analyzed using both ArcGIS Pro and ENVI 5.1. Results were calibrated against a legal gold mining operation between the towns of Anyinam and Osino. The techniques used in this study for detecting mining activities from Landsat imagery consider the design features of these galamseys- large pools of water filling the mining pits, situated in areas of non-vegetated land. Generally, land areas changed by galamsey activities are located outside established towns. Areas identified as potential galamseys were double verified using Google Earth Pro. Double verification involved pinpointing potential illegal mines through image analysis techniques and then confirming them in Google Earth Pro to ensure they were mines and not established communities or agricultural areas. The remote sensing techniques shown in this study can be adopted by the Ghana government to preliminarily identify and monitor galamseys, which can then be confirmed using drone technology or in-situ verification.