CHARLESTON, S.C. (WCBD)- The South Carolina and Georgia coasts are likely to see “significant” effects from Ian, according to a new forecast by the U.S. Geological Survey (USGS).

Ian is expected to restrengthen to a Category 1 hurricane before making landfall along the South Carolina coast on Friday.

USGS researchers forecast the waves and surge caused by the storm are likely to cause 11% of South Carolina’s and 1% of Georgia’s dunes along sandy beaches to be continuously covered by ocean water.

Inundation is the most severe type of storm effect on coastal beaches followed by overwash, which occurs when water levels reach higher than the top of dunes. When a beach is overwashed, sand can be pushed inland, causing changes to coastal landscapes and blocking roads.

For Ian, USGS researchers expect that roughly 43% of South Carolina’s and 24% of Georgia’s dunes along sandy beaches to be overwashed.

Together, inundation and overwash can reduce the height of protective sand dunes and alter beach profiles leaving areas behind the dunes more vulnerable to future storms.

As for erosion, USGS researchers expect 99% of South Carolina dunes and 77% of Georgia dunes to see some level of erosion caused by Ian.

To create a coastal change forecast, USGS uses National Hurricane Center (NHC) storm surge predictions, National Oceanic and Atmospheric Administration (NOAA) wave models, and information on the expected landfall region’s beach slope and dune height.

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