Sand dunes may not have a reputation for their sturdiness, but they are critical buffers protecting shorelines from hurricanes and tropical storms. When stormwaters erode, flood or wash away sand dunes during coastal storms the coastal communities, habitats and infrastructure behind them become more exposed to possible flooding.

As a storm approaches land, USGS scientists forecast how it may reshape the coastline, and what that may mean for erosion and flooding impacts on coastal communities. They accomplish this with two different publicly available models that produce detailed forecasts of a storm’s likely effects on sandy beaches along the Atlantic and Gulf coasts. These models and their forecasts can help emergency managers make critical decisions before a major storm strikes, including which areas to evacuate, which roads to use and where to pre-position storm cleanup equipment.

The first model, called the USGS Coastal Change Hazard Forecast, is used to predict the probability and locations protective sand dunes are likely to be eroded at their bases, overtopped by storm waves or inundated by seawater. The model covers most of the nation’s Atlantic and Gulf coasts and uses observations of beach topography and National Hurricane Center-modeled surge and waves. The USGS coastal hazards storm team works with the NHC to update the USGS coastal change forecasts several times a day. Forecasts for specific storms typically begin 72 hours before it’s expected to make landfall. Coastal change forecasts are available at the USGS Coastal Change Hazards Portal. 

The USGS has expanded this capability to cover hurricane scenario-based forecasts for Puerto Rico and this is the first hurricane season it’s available for the island’s coastal communities. Real-time forecasts are not yet available for landfalling storms in Puerto Rico, but USGS experts are working to deliver this ability in the future.

A newer model developed by USGS scientists in collaboration with NOAA is called the Total Water Level and Coastal Change Forecast. The model estimates the location and timing of potential coastal impacts as well as the height of stormwater levels at the shoreline. This continuously operating model produces six-day forecasts of hourly water levels for almost 3,000 miles of coastline extending from Texas to Maine. These forecasts, which focus on specific sites within several regional stretches of coastline, are available online via the Total Water Level and Coastal Change Forecast Viewer.

For more information on USGS coastal change forecasts, check out this USGS geonarrative.  

Come back next week to learn how flooding caused by hurricanes and tropical storms can threaten coastal and inland communities, and how real-time USGS water monitoring information is used to forecast floods and protect communities.

* Editor’s note: The photo at the top of the page shows a sand dune in Flagler County, Florida that experienced severe erosion due to strong waves caused by Hurricane Ian. The category 4 hurricane made landfall in Southwest Florida in September 2022 and impacted both the Gulf of Mexico and Atlantic coasts.  Photo by Danielle Faletti. Used with permission.

Learn more about USGS hurricane science.

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