Hurricane Delta And TX/LA Beach Erosion

Credit: USGS, Public domain.

Hurricane Delta has caused erosion to the Texas and Louisiana coasta according to officials with the U.S. Geological Survey who are using new technology to gauge erosion.

This Coastal Change Storm Hazard Team forecast was made at 4AM CDT October 9, 2020 and shows forecast beach erosion at the base of the dunes (the strip of colored bars closest to the coast), overwash (middle strip) and inundation (outer strip) from Hurricane Delta. The model accounts for sandy beaches and barrier islands and does not include marshes, forested or sea walled shorelines. Credit: USGS, Public domain.

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.

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.

To keep up with the estimated coastal change of future storms go to  https://marine.usgs.gov/coastalchangehazardsportal/.

Source: U.S Geological Survey