ASSESSMENT OF THE SPATIOTEMPORAL CHANGES DUE TO ARTISANAL AND SMALL-SCALE MINING IN SOUTHERN NIGERIA

Abstract

The rapidly increasing human populations and expanding agricultural and industrial activities have brought about extensive land use changes and demands on natural resources. The conflict between mining activities and environmental protection has intensified over recent years, emphasizing the need for improved information on the dynamics of environmental impacts at local and regional scale. Analysis of land use/land cover change (LULCC) and their impacts on the natural environment is essential in policy decision for effective sustainability of the earth system. This study investigated and evaluate the environmental impacts of artisanal and small-scale mining operations on the environmental degradation and concerns arising from such activities in selected host communities (Akoko Edo, Ijero and Ilesa). Vegetation, water, built up expansion and land surface temperature dynamics were examined for the selected years (1986/7, 2002 and 2017) using corresponding indices normalised difference vegetation index (NDVI), normalised difference water index (NDWI), normalised difference built up index (NDBI) and Land Surface Temperature (LST), respectively. Landsat images of 1986/7, 2002 and 2017 were analyzed using ArcMap 10.5. A gradual decrease in the NDVI values was observed across Akoko Edo and Ijero Ekiti with a corresponding change in the highest NDVI values. Mean LST values are in the order 24.63°C (1986) < 25.26°C (2002) < 26.32°C (2017) for Ijero Ekiti study area while mean LST values are in the order 24.30°C (1986) < 24.46°C (2002) < 25.82°C (2017) in Ilesa study area. The Normalized Difference Water Index (NDWI) was known to be strongly related to the plant water content. It is therefore a very good proxy for plant water stress. MNDWI seemed a more reliable indicator as the index was able to enhance the water surfaces more clearly as indicated in the case of Akoko Edo study area. High surface temperatures were experienced over urban areas and uncultivated bare land in all the periods of study due to its high heat capacity. The study demonstrated that changes in land covers through urban development has affected the natural functioning of ecosystems. As such, adequate natural resources management through effective policies formulation are required to ensure sustainable development.