Recent expansion of artisanal gold mining along the Bandama River (Côte d’Ivoire)

Abstract

• Artisanal and small-scale gold mining is a serious threat to the environment. • In Ivory Côte d’Ivoire, this activity has developed very quickly recently. • The lack of geographical information is an obstacle to the regulation. • The monitoring of artisanal mining from space can help governements. Recent development of small-scale gold mining activities in Côte d’Ivoire is a serious threat to the environment because of deforestation, soil scrapping, pit mining, over-use of water resources and pollution of surface and ground waters by mercury, cyanides, and acids. The challenge for the governance of this activity is to resolve the tension between the desired development of a small-scale mining activity, which may benefit the local and national economy, and the impacts of this activity on the environment. The regulation of the exploration and exploitation of mining sites and the promotion of best practices was part of the National program for the rationalization of gold-panning in Côte d’Ivoire. The capacity of the government to monitor the expansion of numerous mining sites disseminated all over the country is one of the key aspects for successful implementation of these policies. This study explores the potential value of computer-assisted mapping of artisanal mining sites based on Sentinel-2 imagery. The detection method, using artificial intelligence and training data sets generated during field campaigns, was inspired from a previous experience in Senegal. It was applied to a region of about 600 km 2 in Central Côte d’Ivoire. Annual maps of areas affected by the mining activities were produced for the period 2018 – 2021. The areas affected by artisanal mining activities expanded from 3.39 km 2 to 8.80 km 2 in December 2021, corresponding to an average growth rate of 0.24 km 2 /month. The temporal and spatial resolution of the Sentinel satellite imagery proved to be useful to map and quantify the expansion rate of artisanal mining sites in Côte d’Ivoire. Recommendations are made for the integration of these tools into plans for the development of small-scale mining activities in Côte d’Ivoire that would be more respectful of the environment and societies.