Monitoring the development of artisanal mines in South Africa

Abstract

Artisanal and small-scale mining (ASM) activities have risen significantly in sub-Saharan Africa and other developing regions. ASM is increasingly being recognized as a viable pathway for sustainable livelihood building and poverty alleviation. Lack of information regarding the spatial distribution of artisanal mines and their growth over time has created significant gaps in terms of awareness in the affected communities. The systematic documentation of ASM mining is often made challenging by the seasonality and nomadic nature of these rudimentary operations. In this study, we aimed to quantify changes in vegetation cover, bare soil, and mined open pits from 2014 to 2018 due to the impacts of ASM using SPOT 6 satellite imagery. With Prieska, South Africa as a case study, morphological classification was used to delineate mined open pits and the Spectral Angle Mapper to map the changes in vegetation and bare soil. The results show a progressive increase in areas being mined for the semiprecious stone tiger's eye from 2014 to 2018. High classification accuracies of above 92% in mapping were achieved to identify artisanal open pits using morphological profiles, and classification accuracies of above 80% for mapping vegetated areas and bare areas using Spectral Angle Mapper. The results of this study also show the continuous decrease of vegetated areas and expansion of bare soil surfaces from 2014 to 2018, making the areas more vulnerable to land degradation, particularly soil erosion.