Abstract:
This study developed a pollutant transport modeling framework to track lead and mercury
contamination in the River Okame catchment, a region significantly impacted by artisanal and small-scale gold mining activities. Using the Soil and Water Assessment Tool (SWAT),
hydrological and pollutant transport processes were modeled to assess the extent of heavy metal
contamination. Data on hydrology, land use, soil types, mining activities, and heavy metal
concentrations were collected and integrated into SWAT for simulation. Model calibration and
validation were conducted using observed water quality and streamflow data to enhance prediction
accuracy.
The findings revealed alarmingly high levels of lead and mercury in dissolved-bound forms,
exceeding recommended environmental and health safety thresholds. Pollutant transport analysis
identified critical contamination hotspots, primarily near active mining zones and downstream
deposition areas. Scenario-based modeling demonstrated that unregulated mining practices and
land-use changes significantly exacerbate heavy metal pollution, particularly during high-flow
events.
The study highlights the urgent need for mitigation measures, including use of borax and reduction
in the amount of mercury level to reduce contamination risks. The results provide a scientific
foundation for policymakers and stakeholders to implement sustainable management practices
aimed at safeguarding water quality, aquatic ecosystems, and public health in the River Okame
catchment.
