Pre-and Post-Colonial Sediment Sources and Storage in the Lower Neuse Basin, North Carolina

Several lines of evidence are used to estimate pre-and post-colonial sediment production, transport, and storage in the lower Neuse River basin on the North Carolina Coastal Plain. Soil profile truncation indicates upland erosion rates of >9.5t/ha/yr during the post-European period, while pre-colonial rates were negligible. Comparisons of sediment yields between streams in forested and agricultural basins suggest that stream sediment loads have risen dramatically following colonial-era land clearing. Pedological indicators of sediment sources in contemporary and pre-Holocene alluvial soils show a change in dominant sediment source from an important upper-basin Piedmont contribution to a situation where Piedmont sediment is overwhelmed by Coastal Plain sources. Finally, most of the increased sediment input to the lower Neuse River and its tributaries has apparently been stored as alluvium. This is indicated by limited siltation of the Neuse estuary and limited pedogenic development on floodplains and stream terraces. Modern sediment dynamics are so different from those of the pre-colonial period that the stratigraphic record is insufficient for predicting future responses of the river to environmental change. [Key words: erosion, sedimentation, Neuse River, coastal plain, human impact, North Carolina, sediment budget.]