SHORT-TERM EROSION OF WETLAND SHORELINES IN THE ALBEMARLE-PAMLICO ESTUARINE SYSTEM

Shoreline erosion has been recognized as a problem with important human and ecological ramifications (e.g., property and marsh loss) in coastal zones. Previous studies have typically focused on oceanfront shorelines; however the rate of shoreline erosion along protected mainland shorelines can exceed that of oceanfront areas. In the Albemarle-Pamlico Estuarine System (APES), prior research has focused on long-term changes in the estuarine shoreline. For example, work has shown the highest rates of shoreline erosion (from 1 m yr^-1 to as high as 3 m yr^-1) occur along the exposed sound areas and at the mouths of major sub-estuaries (e.g., Pamlico River mouth), and elsewhere rates are commonly 0.25 m yr^-1. The goal of this research was to quantify changes in estuarine wetland shorelines over shorter time periods (months to a few years) and, associated with individual storm events.

Five wetland sites were chosen across the APES to represent a range of wetland types and locations. These sites were digitized using the most recent set of North Carolina State aerial photography according to a methodology established by the North Carolina Division of Coastal Management. To determine an accurate current shoreline position in the field, each site was surveyed during early summer 2010 using an RTK-GPS. Sites were reoccupied on a bi-monthly basis from August 2010 to February 2011 and following storm events. A Balloon Aerial Photography System was also employed to image the shoreline. Shoreline change was analyzed for each time-step and methodology (RTK, Balloon System, and on-screen digitizing). Rates of shoreline erosion for the sites were found to be similar to previous work. RTK-GPS survey following a single storm event, Hurricane Earl, which passed within 100 miles of the study area, had similar rates of shoreline erosion. Accretion was locally measured at several of the study sites during bi-monthly surveys, but generally, net erosion is dominating the change and slow stay erosion from regular wave action appears to be controlling change based on this preliminary dataset.