Abstract:
Soil erosion is a persistent environmental concern in Rwanda, particularly in regions affected by concentrated mining and steep topography. The main problem investigated was the inadequately understood spatial distribution of soil erosion risk caused by mining activities and its subsequent impact on vegetation cover in the Rugendabari sector of Muhanga District. This study examined the spatial distribution of soil erosion risk caused by mining activities using the Revised Universal Soil Loss Equation (RUSLE) combined with Geographical Information Systems (GIS) and remote sensing techniques, the study models soil loss by analyzing key factors including rainfall erosivity, soil erodibility, slope length and steepness, cover management, and conservation practices using satellite imagery (Landsat 8, ESRI LULC) and other relevant spatial data from 2017 to 2024. The results from the RUSLE model indicate that the mean annual soil erosion rates range from 0 to 2652 tons/ha/year. Where the soil loss value between 0-177tons/ha/year affected the 36.9% of total area with 1532.2 ha found in very low class, soil loss between 177-458tons/ha/year affected the 28.9% of total area with 1198.4 ha found in low class, soil loss between 458-780tons/ha/year affected the 21% of the total area with 870.7ha found in moderate class, soil loss between 7801217 tons/ha/year affected the 10.8% of the total area found in high class and the soil loss range between 1217-2652 tons/ha/year affected 2.4% of the total area with 101.3 ha found in very high class. The field measurement made to determine the TSS found in Birikana stream showed that TSS increased in the sediment load of Birikana stream, with an estimated 234,026.5 tons of sediment discharged annually into the Nyabarongo River. The results reveal that extensive excavation, deforestation, and particularly the improper management of mining waste, such as unconsolidated rock debris and tailings on steep slopes, are primary drivers of erosion in the Rugendabari sector. This substantial sediment yield not only degrades water quality and damages critical infrastructure but also harms aquatic habitats. The findings indicate that mining activities significantly contribute to soil loss, sediment yield, and vegetation loss, especially around active and unrehabilitated mine sites. Erosion rates were highest in areas with exposed steep slopes and minimal vegetation cover. The results emphasize the urgent need for sustainable land use planning, effective erosion control measures, and ecological restoration in mining areas.
