Predictions of Relative Sea-Level Change and Shoreline Erosion over the 21st Century on Tangier Island, Virginia

Abstract

For approximately 300 years, Tangier Island, located in the middle of the Chesapeake Bay, USA, has been continuously populated by up to 1,000 residents. At present, the population is near 700. The island is very flat and low, and residents live on three sandy ridges with elevations of about 1.0–1.5 m above mean sea level (msl). Over the past century, the relative sea level there has risen about 31 cm, in part due to the estimated subsidence of the island (in other parts of the Bay as well) at a rate of about 18 cm per century. As the level of the sea continues to rise in the 21st century and as shoreline erosion continues, the very existence of the island is in jeopardy. In this article, projections are made to the year 2100 in terms of how sea-level rise and continued shoreline erosion will impact the island. To evaluate impacts, several years of historical tidal levels were extrapolated to the year 2100, using the predicted sea-level changes. The predictions were compared with the observed levels in year 2000 to show the effects of relative sea-level change.Shoreline erosion was also examined. The first map with enough accuracy to correctly depict temporal changes in shoreline was from 1850. When that map of Tangier Island was then compared with more recent ones, it was found that erosion was much more severe on the western shore due to the longer fetch over which wind-generated waves could develop. Implications for continued human habitation to the year 2100 were examined and the future island size was projected, assuming no additional human intervention beyond the present.