Hurricane Sandy May Alter Shoreline

It is predicted that nearly three quarters of the coast along the Delmarva Peninsula is likely to experience beach and dune erosion as Hurricane Sandy triggers landfall and overwash is expected along nearly half of the shoreline.

Overwash, the landward movement of large volumes of sand from overtopped dunes, is forecasted for portions of the east coast with the projected landfall of the storm. The severity of overwash depends on the strength of the storm, the height of the dunes, and how direct a hit the coast takes.

This prediction is a part of a larger assessment of probable coastal change released by the U.S. Geological Survey.

"Model forecasts are run anew for each hurricane, as each case has unique factors in terms of storm intensity, timing with respect to tides, angle of approach, and must account for ever-changing details of coastal dune configuration," said USGS Director Marcia McNutt. "These models help us understand where emergency management resources might be most needed."

"On the Delmarva Peninsula, near the storm's expected landfall, close to three quarters of the sandy coast is expected to see beach and dune erosion. Fifteen percent of the coast is very likely to be inundated by waves and storm surge," said USGS Oceanographer Hilary Stockdon from the USGS St. Petersburg Coastal and Marine Science Center.

It is said that waves and storms flow would carry large amounts of sand across coastal environments. The sand would be deposited both inland and offshore and causing changes to landscape.

According to the model, along the New Jersey shore, 81 percent of the coast is very likely to experience beach and dune erosion, while 7 percent is very likely to experience overwash. It also indicates that on the south shore of Long Island, N.Y., including Fire Island National Seashore, 43 percent of the coast is very likely to experience beach and dune erosion. Overwash and inundation are not expected in these areas because of the relative high dune elevations.

According to USGS geologist Cheryl Hapke, "Many of the sandy beaches along the mid-Atlantic Coast have become increasingly vulnerable to significant impacts such as erosion because of past storms, including Hurricanes Ida (2009) and Irene (2011), as well as large northeastern storms in 2005 and 2007."

"Beaches and dunes often serve as the first line of defense for coastal communities against flooding and other hazards associated with extreme storm" said Hapke, "Any compromise to these features means that storm-related hazards are more likely to threaten coastal property, infrastructure, and public safety during a future extreme storm event."