Monitoring, modeling, and fingerprinting suspended sediment in a southern Piedmont stream
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Sediment is one of the most important non-point source pollutant impairing water bodies in the United States and around the world. The objective of this research was to develop a new approach to watersheds with high sediment loads in the southern Piedmont incorporating geomorphic analysis of fluvial systems and to determine suspended sediment sources and their relative contributions using a fingerprinting approach. The GIS based SWAT model was used to simulate suspended sediment transport in the study watershed and to test the effect of spatial resolution of soil data on model predictions for flow and sediment. Results showed that spatial resolution of soil data did not have a significant effect on the model predictions for flow and suspended sediment in this Piedmont watershed. The suspended sediment load estimates for the study watershed was high and comparable with streams in the Piedmont region with unstable channels. Geomorphic analysis indicated that mass wasting and fluvial erosion were the dominant erosion processes in the stream channels. Sediment fingerprinting showed that eroding stream banks contributed about 60% of the total suspended sediment load followed by construction sites, unpaved roads and road ditches that contributed about 23-30%. Pastures contributed about 10-15% suspended sediment in this watershed. The SWAT model also indicated stream channels as the primary source of suspended sediment. The relative source contribution of suspended sediment predicted by the SWAT model was comparable with the results of the fingerprinting study.