Hurricane Delta is expected to make landfall Friday, bringing erosion and some flooding to sandy coastal beaches and barrier islands in Louisiana and Southeast Texas near the storm’s landfall, according to the U.S. Geological Survey’s updated coastal change forecast. Though the extent of the affected area is smaller than it was in earlier USGS coastal forecasts, some sandy beaches in Louisiana may still be heavily damaged by the storm.  

Louisiana is expected to bear the brunt of the storm’s strong waves and surge, with 35% of the sandy beaches forecast to be inundated, or continuously covered by ocean water. This is the most severe type of storm effect on coastal beaches, with flooding behind the dunes that may affect coastal communities. Minimal impacts are expected for Texas, Mississippi and Alabama. 

“The numbers don’t mean that the impact overall has decreased. They mean that the hazards will be more localized along the storm’s path,” said USGS oceanographer Kara Doran. “That means the effects will not be as widespread on Texas and Louisiana beaches, overall.”  

Scientists and emergency managers can use USGS’s forecasts - produced before major hurricanes and other powerful storms - to plan evacuations and position clean-up equipment to have it ready after the storm.  

The USGS coastal erosion prediction covers only sandy shorelines, such as beaches and barrier islands, and not marshes, forests or shorelines with seawalls or other armoring.  

The least severe level of storm damage on sandy shorelines is erosion at the base of sand dunes, known as collision. About  60% of Louisiana’s sandy shorelines and 45%of Texas beaches and barrier islands from Matagorda to the Louisiana border are predicted to erode at the dunes’ base.  

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Overwash is the middle range of potential storm impacts on beaches. As waves and surge reach higher than the top of the dune, overwash can transport large amounts of sand across coastal environments, depositing sand inland and causing significant changes to the landscape. Overwash can reduce the height of the coast’s protective line of sand dunes, alter the beaches’ profile, and leave areas behind the dunes more vulnerable to future storms.  

About 64% of  Louisiana’s sandy beaches are very likely to be affected by overwash. Texas is forecast to have 17% of its beaches overwashed.  

The forecast of Delta’s effects on sandy shorelines at landfall is based on results of the USGS Coastal Change Forecast model, which has been in use since 2011 and is continually being improved. The Coastal Change Forecast model uses the National Hurricane Center’s storm surge predictions and National Oceanic and Atmospheric Administration wave forecast models. The USGS model then adds detailed information about the forecast landfall region’s beach slope and dune height. The predictions define “very likely” effects as those that have at least a 90 percent chance of taking place, based on the storm’s forecast track and intensity.   

The latest coastal change forecast for Delta is at  https://marine.usgs.gov/coastalchangehazardsportal/. The coastal change forecast will be updated as the National  Hurricane Center’s surge forecasts change.  

As the USGS continues to take all appropriate preparedness actions in response to Delta, those in the storm's projected path can visit  Ready.gov  or  Listo.gov  for tips on creating emergency plans and putting together an emergency supply kit.