Past Decade of Extreme Storms Leaves Coasts Vulnerable

By Abby Sallenger, Hilary Stockdon, and Ann Tihansky May / June 2010

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Impacts on the coastline of the northern Gulf of Mexico from a decade of extreme storms have left many coastal areas vulnerable to future storm events, according to the U.S. Geological Survey (USGS) Coastal Change Hazards Program. Over the past 10 years, 58 percent of the U.S. Gulf of Mexico coastline has been hit by hurricane-force winds. Major hurricanes like Ivan, Katrina, Rita, and Ike have pummeled and eroded beaches and sand dunes along the Gulf Coast. These coastal features are commonly the first line of defense for coastal communities and ecosystems against extreme storms.

Above: Gulf of Mexico, showing coastlines affected by hurricanes from 2000 to 2009. [larger version]

"Recent hurricanes have caused significant erosion of coastal features and, in some places, lowered barrier-island elevations. It is important to understand how such lowering of beaches and dunes can increase the vulnerability of coasts to future storms," said Abby Sallenger, USGS oceanographer in St. Petersburg, Florida.

"The vulnerability of barrier islands or coasts to inundation during extreme storms is determined, in part, by the elevation of the seaward-most sand dunes or beach berm. The dunes act as an important line of defense, taking the brunt of waves and storm surge and somewhat reducing the impact on coastal communities. On engineered coastlines, seawalls or other structures may be used to provide this protection," said Hilary Stockdon, another USGS oceanographer in the St. Petersburg center.

Above: Assessment of inundation potential (storm surge minus dune elevation) for Galveston, Texas, using modeled storm surge based on Hurricane Ike storm conditions and landfall location. In most areas, severe inundation (red colors) and coastal change were expected because updated surge estimates exceeded the elevations of the primary dunes/berms. (From Hurricane Ike - Post-Landfall Assessment of Potential Coastal-Change Impacts). [larger version]

One aspect to improving preparation for, emergency response to, and recovery after extreme storms is predicting the types of coastal change that may occur when a hurricane makes landfall. The Coastal Change Hazards Program studies the response of coastal environments to extreme waves, storm surge, and currents. USGS scientists coordinate with other State and Federal agencies in predicting the likely interactions between waves, storm surge, and coastal topography during extreme storms. Accurate predictions can improve response times and provide valuable information to the public, coastal managers, and emergency-response teams.

A paper published in the February 2010 edition of Eos (Transactions of the American Geophysical Union) describes how this predictive ability was tested on Hurricane Ike in 2008.

"Using observations of coastal morphology and models of storm surge, we were able to predict the vulnerability of the Galveston coastline to extreme coastal changes during the landfall of Hurricane Ike," said Nathaniel Plant, lead author of the study. Examples of predictions of coastal-change impacts for Hurricane Ike are posted online at http://coastal.er.usgs.gov/hurricanes/ike/coastal-change/post-landfall-assessment.html.

For more information about the USGS Coastal Change Hazards Program, visit http://coastal.er.usgs.gov/hurricanes/. The full citation for the recent paper is: Plant, Nathaniel, Stockdon, Hilary, and Sallenger, Abby, 2010, Forecasting hurricane impact on coastal topography: Eos (American Geophysical Union Transactions), v. 91, no. 7, p. 65, doi:10.1029/2010EO070001 [http://dx.doi.org/10.1029/2010EO070001].

Storm Impact, Sea-Floor Change, and Barrier-Island Evolution: Scientists Map the Sea Floor and Stratigraphy Around Ship and Horn Islands, Northern Gulf of Mexico March 2009

Gulf Coast Impacts of Hurricanes Gustav and Ike Documented by USGS Extreme-Storms Group October 2008

Coastal Change Hazards: Hurricanes and Extreme Storms U.S. Geological Survey (USGS)

Forecasting Hurricane Impact on Coastal Topography Eos

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May / June 2010

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cover story:
USGS Responds to Deepwater Horizon Oil Spill

Extreme Storms Leave Coasts Vulnerable

Fish and Wildlife Face Risks as Climate Changes

Natural Gas Potential Assessed in Eastern Mediterranean

Open House in Florida

Vulnerability of Coasts to Sea-Level Rise

Best Poster Award from Pacific Section AAPG

May / June 2010 Publications