As Hurricane Ida approached the U.S. northern Gulf coast, the USGS Coastal Change Hazards team produced a series of forecasts for impacts on the beach. Forecasts were updated daily based on wave and storm surge forecasts from NOAA.
Coastal Change Hazards Team Forecasted Hurricane Ida Beach Impacts
Prior to landfall of Hurricane Ida on August 29, 2021, the Coastal Change Hazards Team forecast that 71 percent of Louisiana beaches, 63 percent of Mississippi beaches, and 27 percent of Alabama beaches were very likely to experience dune erosion at the dunes’ base. 58 percent of dunes in Louisiana, 38 percent of dunes in Mississippi and 2 percent of dunes in Alabama were forecast to be very likely to be overwashed by storm waves. 30 percent and 5 percent of dunes in Louisiana and Mississippi, respectively, were expected to be very likely to be inundated (completely submerged) by surge, tide, and waves; no dunes in Alabama were expected to be inundated. These forecasts were part of a USGS News Release and were highlighted on CNN. In addition to special forecasts focused on impacts at the peak of the storm, real-time forecasts were also ongoing in the Total Water Level and Coastal Change Forecast Viewer. In addition to informing the public, forecasts were used to determine placement of sensors for USGS real-time response to Hurricane Ida. After landfall of a storm, the Coastal Change Hazards team uses NOAA imagery, USGS CoastCams, other beach cams, Digital Elevation Models (DEMs) constructed from post-storm aerial imagery and lidar data, and observations from USGS sensors to validate forecasts.
The USGS Coastal Change Forecast model is used to estimate the impacts of elevated waves and storm surge along the coast due to extreme storms. This model has been in use since 2011 and is continually improved.
For more information about coastal change see the geonarrative, "Real-time Forecasts of Coastal Change."