Millions of Americans are currently within Hurricane Matthew’s projected path, and as the powerful storm continues its approach to the Eastern Seaboard residents from South Florida to North Carolina are making preparations for what Matthew may bring. If Matthew’s current track remains constant, one thing is certain – this category four hurricane will bring wide-spread coastal erosion, driven by Matthew’s extreme winds and storm surges.
“What’s important for people to understand with this storm is that it’s large and very powerful,” said Hilary Stockdon, U.S. Geological Survey research oceanographer and the lead developer of a series of coastal change forecasting tools. “Strong winds will create dangerous waves and surge over a large stretch of the coastline, leading to extensive beach and dune erosion.”
There are many factors and variables to consider when trying to determine what a large storm like Matthew might do to the coast and USGS researchers have recently released a forecast of potential coastal changes Hurricane Matthew could cause.
This USGS Coastal Change Forecast model uses the National Hurricane Center’s storm surge predictions and National Oceanic and Atmospheric Administration wave forecast models as input. The USGS model adds information about the beach slope and dune height to predict how high waves and surge will move up the beach and whether the protective dunes will be overtopped. Results of the modeling indicate Hurricane Matthew could have a significant impact on the beaches and dunes of the Southeastern United States.
As of Thursday morning, the coastal change model estimates that Florida’s large eastern coastline has an 80-percent likely chance of beach erosion from Miami to the state border. Georgia’s smaller coastline is estimated to have a 95-percent likely chance of beach erosion while South Carolina has an 85-percent likely chance of experiencing beach erosion across it’s coastline. Because the projections are based on storm-surge forecasts, they change each time the storm surge forecast is updated.
Beach erosion is only the first level of damage a major storm can cause. As waves and surge reach higher than the top of the dune, overwash occurs, often transporting large amounts of sand across coastal environments, depositing sand inland and causing significant changes to the landscape.
The low lying barrier islands of Georgia are very vulnerable to storm surge and waves – around 65-percent of the coastline is likely experience overwash. In South Carolina and the Florida east coast, overwash is expected for about 20-25 percent of the coast. Although dune overwash could happen anywhere, it is most likely to occur in locations with low dune elevations such as Hutchinson Island, Florida; Canaveral National Seashore, Florida; Sea Island, Georgia; and Edisto Island, South Carolina.
Inundation, the most severe impact, occurs when beaches and dunes are completely and continuously submerged by surge. Fifteen-percent of the Georgia coastline is likely to experience beach and dune inundation, while inundation is unlikely in South Carolina and Florida.
A real-time map of these estimates can be viewed on the USGS’ Coastal Change Hazards Portal, which is easily accessible to the public. The coastal change forecast can be used by emergency managers to help identify locations where coastal impacts might be the most severe, such as where roads will be overwashed by sand or where it’s possible that roads might go underwater because of storm surge and large waves.
The coastal change projections are subject to change as Hurricane Matthew makes it’s way closer to land and the most up-to-date forecasts for potential coastal change predictions are available on the National Assessment of Storm-Induced Coastal Change Hazards – Hurricane Matthew page here.
While the final projections for Hurricane Matthew will continue to change, Matthew is forecasted to remain a powerful storm for several days and is likely to damage many parts of the southeastern coastline.