Decadal Washover
Washover is a sandy deposit left behind after storm waves break through dunes along a beach or barrier island. The overwash process and the washover deposit can present hazards to coastal communties through flooding, burial, and shoreline erosion, but washover is also an important process for barrier islands to 'roll over' and keep up with sea-level rise on decadal (>10 years) timescales.
Coastal land forms in a barrier island system labeled, including washover. Source: https://www.nps.gov/articles/upload/GUTIERREZ_CAHA_PanelTalkSept26.pdf
Washover on undeveloped coastlines
washover deposiiton is needed so barriers can move landward and upward through time with sea-level rise. Numerical models tell us that islands can survive in-tact through this process, but this requires sufficient volume of sand to be deposited in washover.
Washover on developed coastlines
In places where people have developed on barrier islands, washover can present a hazard. Sand is often manually removed from roads and placed back on the foredune or beach. This can prevent the island from adapting to sea-level rise and may cause worsening hazards for the local community.
Removal of washover material from NC12 on Pea Island, NC. Photo from NC Department of Transportation Twitter @NCDOT_NC12
Presentations
Eisemann, E.R., Rodriguez, A.B., Gremillion, S.L., Wallace, D.J. (Oct. 2023) Quantifying variations in decadal washover flux at the barrier-island scale using airborne lidar. Oral presentation at the 2023 IGCP Annual Meeting Project 725: Forecasting Coastal Change. Florianopolis, Brazil.
Eisemann, E., Rodriguez, A., Wallace, D., Gremillion, S., Wozencraft, J., Moore, L. (Nov. 2022) Controls on washover change with development density. Poster presentation at the 2022 NC Sea Grant Conference. Raleigh, NC, USA.
Eisemann, E., Gremillion, S., Wallace, D., Wozencraft, J., Moore, L. (Feb. 2022) Washover deposit mapping and volume quantification from regional airborne lidar and aerial imagery. Oral presentation at Ocean Sciences 2022 conference. Virtual.
Publications
Gremillion, S. L., Wallace, D. J., Eisemann, E. R., 2023. Recent Overwash Deposition On Pea Island, NC, USA. Coastal Sediments 2023, 2332-2339. DOI: 10.1142/9789811275135_0214