COMPARATIVE ANALYSIS OF WATERSHED EROSION, RESERVOIR SEDIMENTATION AND SEDIMENT TRACE METALS IN TWO VIRGINIA LAKES
The RUSLE/SDR erosion model estimates 2.149 Mg/ha/yr for Lake Pelham, which is a 410% increase from assumed pristine conditions. For Lake Moomaw, 2.717 Mg/ha/yr of erosion was estimated, a 13% increase from pristine conditions. The average 210Pb-based sediment accumulation rates were 0.348 ±0.053 g/cm2/yr for Lake Pelham and 0.246±0.043 g/ cm2/yr for Lake Moomaw. The geophysical survey results estimates sediment average accumulation rates of 0.599 cm/yr and 1.514 cm/yr for Lakes Moomaw and Pelham respectively. The sediment trace metal results show that both reservoirs have moderate to high enrichment of Cu and little enrichment of Zn and Pb. Overall, Lake Moomaw has relatively low sediment accumulation and watershed erosion rates due to the pristine nature of the watershed, but is also more vulnerable due to the steep slopes that characterize the basin. Comparatively, Lake Pelham has higher erosion rates, sediment accumulation rates and high metal enrichment of Cu and Zn, which directly reflects the impact of human development on its environmental evolution.