Effects of mining activities on Kibali river water quality before the implementation of Kibali gold mine.

Abstract

This is study intended to i) determine the land-use/cover change in Kibali catchment, ii) characterize the quality of Kibali river water before the implementation of Kibali Gold Mine in North-eastern D.R.Congo, and iii) predict hotspot areas of soil erosion and nutrient loading into Kibali catchment. Land-use /cover change was determined by analyzing Landsat images of 1973 and 2005. Water quality was determined quarterly in the main stream since 2010-2012. Hotspot areas for sediment and nutrient loading were determined using SWAT software integrated in ArcView GIS version 3.3. The dominant land-use/cover in the catchment was a mosaic forest (82.57%), followed by grassland (11.04%) and bushland/cropland (6.24%). In 2005, mosaic forest remained the most dominant land-use/cover (81.22%), followed by bushland/cropland (14.27%); and grassland (2.2%). Other land-use/covers in the catchment include mosaic wetland (1.98%), and fresh water (0.03%). The concentrations of surface and underground water were generally below the WHO limits, except for the Al and Hg concentrations in surface waters at the discharge point of the tailings from the OKIMO Plant, and at the confluence of the Doko and Kibali Rivers. The sediments sampled from the Durba Dams had high Cadmium concentrations which are considered to be toxic. Surface water were contaminated by heavy metals included Hg, As, Au and Cd, from OKIMO and artisanal mining activities within the catchment. High sediment, runoff and phosphorus yield were coming from south-western part of Faradje and the western part of Watsa.