Shoreline-Zone Dynamics in Response to Sea Level Rise in North Carolina
Figure 1: Study area location map of the
East Carolina Ecological Effects of Sea-Level Rise research project. The inset
outlines the Albemarle-Pamlico Estuarine System (A) and the Neuse River Estuary
study area (B). (
click for larger image)
The
East Carolina University research team is analyzing the effects of sea-level
rise on the shoreline and shore zone (i.e. vegetation community transition
from wetland to upland) within the Neuse River Estuary (NRE), located in eastern
North Carolina (Figure 1). The NRE is a sub-estuary within the Albemarle-Pamlico
Estuarine System, which is the second largest estuary in the United States
and one of the “28 nationally significant” estuaries (Martin et al., 1996).
Within the Albemarle-Pamlico Estuarine System, the shoreline has been categorized
into four main shoreline types: sediment bank, organic, combination, and back-barrier (Riggs
and Ames, 2003). Previous work has shown that average erosion rates of these
shoreline types vary between 0.43 and 0.98 meters per year (Riggs and Ames,
2003). Qualitative data suggests that physical parameters, including fetch,
offshore slope, shoreline geometry, bank height, bank composition, and fringing
vegetation, determine the rate of erosion along these shorelines (Riggs and
Ames, 2003).
The shore zone of the NRE is typically characterized by marsh grassland or
swamp forest vegetation communities (i.e. organic shorelines). As sea-level
rises these communities tend to transgress landward. If the landward slope
is too steep, however, shore zone transgression stalls and these communities
may be destroyed by erosion over time (Brinson et al. 1995, Young 1995).
To quantify changes of the shoreline and shore zone over time as a result
of sea-level rise, the use of aerial photography will be implemented. Historical
aerial photographs from 1958 have been obtained from the North Carolina Geological
Survey, in addition to 1982 Color Infrared aerial photographs of select areas
within the NRE, purchased from the United States Department of Agriculture.
These aerials will be georeferenced to the 1998 Digital Orthophoto Quarter
Quadrangles available from the Unites States Geological Survey. For each year
of aerial photography, the shoreline and shore zone communities will be delineated.
Variables believed to be associated with changes to these coastal environments
(e.g., fetch, landward slope and elevation) will be statistically evaluated.
The relationship of these variables to changes in shoreline and shore zone
observed over the forty-year time period may offer insight into the future
effects of rising sea-level on estuarine shores.
Works Cited
Brinson, M.M.; Christian, R.R., and Blum, L.K.. 1995. Multiple states in the
sea-level induced transition from terrestrial forest to estuary. Estuaries,
18, 648-659
Martin, D. M.; Morton, T.; Dobrzynski, T., and Valentine, B. 1996. Estuaries
on the Edge: the Vital Link Between Land Sea . Washington , D.C.: the
American Oceans Campaign, 297 p.
Riggs, S. R. and Ames, D. V. 2003. Drowning the North Carolina Coast :
Sea Level Rise and Estuarine Dynamics. Raleigh , NC : North Carolina
Sea Grant, 152 p.
Young, R. S. 1995. Coastal wetland dynamics in response to sea-level
rise: transgression and erosion. Durham, North Carolina : Duke
University, Ph D Thesis, 182 p.
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