33 Coastal Resiliency, Storm-Damage Reduction, Navigation, and Other Applied Geological Studies or Projects Focused on Land-Sea Transition

Friday, 1 April 2016
1:30 PM - 5:30 PM
Richland B

UNDERSTANDING THE PHYSICAL VARIABLES INFLUENCING PATTERNS OF SHORELINE CHANGE ALONG A SECTION OF SOUTH CAROLINA'S CENTRAL COASTLINE FROM 1939 TO PRESENT-DAY

Paper number: 33-7
Program: Theme Sessions
Time: 3:30 PM – 3:50 PM

Authors

Abstract

The physical variability of a shoreline's position can be attributed to and is dependent on a range of factors. While the daily impacts of onshore wind, waves, and longshore currents play a major role in shaping coastlines, variables including availability of beach-compatible sediment as well as the incidence of large storm events can also cause visible impacts. The geologic character and underlying framework of the coastline can also lead to variability in rates of erosion and accretion. Patterns of estuarine and beachfront shoreline change along a section of South Carolina's central coast south of Winyah Bay were evaluated through rate-of-change calculations generated using AMBUR (Analyzing Moving Boundaries Using R). Shorelines used in these calculations were delineated from aerial photographs and coincide with events that had the ability to influence sediment dynamics along the coast, most notably the emplacement of a dam on the Santee River in the 1930's and the landfall of Hurricane Hugo in 1989. Information on the surficial geology of the area was also analyzed in combination with shoreline rate-of-change calculations to better understand how this variable (considered in terms of its risk value in a manner similar to the USGS's Coastal Vulnerability Index) impacts patterns of erosion and accretion in the study area. Temporal and spatial variability in the position of beachfront and estuarine shorelines is apparent in the area south of the Winyah Bay jetties, and although notable erosion has occurred, a significant section of marsh and beachfront known as Mother Norton Shoal has accreted between the jetties and adjacent to Tom Yawkey Nature Center Heritage Preserve over the time period studied. Potential impacts of former irrigation ditches constructed for rice cultivation are also discussed within the context of estuarine shoreline change. Fully understanding the variability of a shoreline's position is dependent on placing it within a context that incorporates the scale of the impacts that different variables have on that specific location.

Geological Society of America Abstracts with Programs. Vol. 48, No. 3

doi: 10.1130/abs/2016SE-273667

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