The Effect of Mining on the Pampana River Basin, Sierra Leone

Abstract

Mining activities within the Pampana River Basin in Sierra Leone have intensified over recent decades, raising concerns regarding the degradation of surface and groundwater quality and the sustainability of water resources for domestic and agricultural use. This study evaluates the impact of artisanal and small-scale mining on the physicochemical, microbiological, and hydrochemical characteristics of the Pampana River and adjacent groundwater sources. Water samples were collected from upstream, midstream, downstream, and borehole locations within the basin and analyzed using field measurements, laboratory investigations, hydrochemical assessment techniques, and spatial analysis tools. Physicochemical parameters, microbial indicators, Water Quality Index (WQI), irrigation suitability indices, and hydrochemical facies were evaluated to determine the extent of mining-related contamination and water usability. The results indicate significant spatial variations in water quality across the river basin. Elevated turbidity, total dissolved solids, color, and microbial contamination were observed, particularly in the midstream and downstream sections where mining activities are concentrated. Upstream and borehole samples generally exhibited better water quality conditions and lower contaminant levels. Hydrochemical analysis revealed bicarbonate (HCO₃⁻) as the dominant anion, while sodium (Na⁺) was identified as the dominant cation within the basin. Piper and Schoeller diagrams classified the river water predominantly within sodium-bicarbonate hydrochemical facies. Water Quality Index analysis classified upstream water as excellent for drinking purposes. In contrast, midstream and downstream waters were categorized as unsuitable for potable use due to microbial contamination and elevated pollution levels. Irrigation suitability assessment showed that most samples remained within acceptable irrigation classes despite varying salinity and sodicity conditions. The study demonstrates that uncontrolled mining activities are contributing to the deterioration of water quality within the Pampana River Basin and pose increasing environmental and public health risks to surrounding communities. The findings provide important baseline information for sustainable water resource management, environmental monitoring, and policy formulation in mining-affected river basins in Sierra Leone.