Late Holocene Stratigraphy and Sedimentary Facies Distribution of an Anthropogenically Modified Delta Plain (Santee River Delta, South Carolina, U.S.A.)

• Published in: Journal of coastal research 2024-02, Vol.40 (4), p.623-646
• Main Authors: Long, Joshua H., Hanebuth, Till J.J., Durica, John T., Hawkes, Andrea D.
• Format: Article
• Language: English
• Subjects: anthropogenic coastal system; Anthropogenic factors; Bathymetric data; Coastal environments; Coastal zones; Core analysis; Delta; Deltas; depositional processes; Embankments; Environmental changes; Floodplains; Geomorphology; Holocene; Holocene stratigraphy; Human influences; Mass spectrometry; Mass spectroscopy; Radiocarbon dating; Rice fields; Rivers; Sediment; Sediment distribution; Sediment samplers; Sediment samples; Sedimentary facies; Sediments; Stratigraphy; Water analysis; Water circulation
• ISSN: 0749-0208; 1551-5036
• DOI: 10.2112/JCOASTRES-D-23-00057.1

Long, J.H.; Hanebuth, T.J.J.; Durica, J.T., and Hawkes, A.D., 2024. Late Holocene stratigraphy and sedimentary facies distribution of an anthropogenically modified delta plain (Santee River Delta, South Carolina, U.S.A.). Journal of Coastal Research, 40(4), 623–646. Charlotte (North Carolina), ISSN 0749-0208. The Santee River of South Carolina has the second largest watershed in the eastern United States and forms the largest river-fed delta along the U.S. east coast. Anthropogenic modifications to the delta plain of the Santee River, and in many coastal environments within the region, have significantly altered the natural configurations of floodplains, channels, and shorelines. This study incorporated historic and modern state-of-the-art data sets and methods to evaluate the sediment distribution within the modern delta plain as well as the record of environmental change throughout the late Holocene as it is preserved within the subsurface stratigraphy. The study incorporated high-resolution seismo-acoustic and bathymetric data, detailed sediment core analysis, accelerator mass spectrometry 14C dating, micropaleontological analysis, and surface sediment samples to define geomorphic zones based on dominant depositional processes related to fluvial discharge, tides, and waves. Tidal- and wave-influenced conditions were established in the delta plain by around 3 kyr BP and continued into historic times, when the construction of rice fields across most of the delta plain fixed channel positions and isolated floodplains from flood-related sedimentation. Sediment distribution in the modern delta plain is significantly influenced by the maintained network of artificial canals and embankments associated with these historic fields. The influence of these modifications can also be seen within the stratigraphy beneath the delta plain, recording local changes in deposition and erosion that resulted from a modification in water circulation and sediment supply.