Potential Impacts of Flooding on Alluvial Gold Mining Activities in Parts of Ilesha-Egbe Gold Field, Osun State, Nigeria.

Abstract

The study mapped mining communities in parts of Ilesha-Egbe gold field in Osun State, South-West (SW) Nigeria, with their respective mining sites, their elevation above sea level and the average depth of mining pits in meters. This was done with a view to determining the potential impacts of flooding on mining activities in these areas. Geological map from Nigeria Geological Survey Agency (NGSA), Advanced Space borne Thermal Emission and Reflection Radiometer- Global Digital Elevation Model (ASTER-GDEM) from Global Land Cover Facility (GLCF) and topographic map from Office of the Surveyor General of the Federation (OSGOF) in Nigeria were used for this study. Geology and topographic maps were interpreted for drainage channels and rivers. These and other information were incorporated in mapping and interpreting the mine localities with their respective characteristics. ASTER-DEM was used to generate elevation information like DEM and slope. Stream ordering was done for the digitized drainages and buffering analysis was done for the respective mining points to determine how the mines will be affected in the event of a flood. Results indicate that the study area is well drained with abundant alluvial gold deposit with mines lying on drainage channel. In the events of flood, mine pit will be filled or partially filled with water and areas with pay-streaks easily flooded. Water runs down slope rather than infiltrates and run-off causes flooding at the lower courses of the water body and this provides for gold dust recharge downstream, opening up new gold exploitation areas.