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In Harm’s Way: Measuring Storm Impacts to Forecast Future Vulnerability
Hello, and welcome to the U.S. Geological Survey Coastal and Marine Geology Podcast. I’m Matthew Cimitile. Today, we are discussing the science behind understanding coastal vulnerability and hazards posed by extreme storms.
Extreme storms like hurricanes historically bring massive and widespread destruction to areas along the Atlantic Coast and Gulf of Mexico. Notable major hurricanes of the past like Camille, Ivan, Katrina, Rita, and Ike have pummeled and flooded coastal communities, causing billions of dollars worth of damages, thousands of lives lost, and increasing coastal vulnerability to future storms. The USGS Coastal Change Hazards Program studies the response of coastal environments to the extreme winds, waves, and currents brought by such storms.
“The overall objective of our program is to try to determine where our coast is most hazardous, where we should think twice about putting up infrastructure and buildings and certainly not to rebuild in some areas after extreme storms. There are places along our coastline that have been wiped out repeatedly over the past 30 to 40 years and we’ve gone back and rebuilt in those locations. What we are trying to do is quantify why those and other locations around our country are extremely vulnerable to extreme storms so we might avoid these kinds of problems in the future.”
A lesser-known toll from violent storms is the one they take on the coastal environment that support these communities. Coastal features like beaches and sand dunes usually serve as a first line of defense for coastal communities. For example, barrier islands help dissipate the energy of tropical storms while sand dunes absorb some of the rushing storm surge before it washes onto land.
Continued battering by intense and frequent extreme storms - combined with natural erosion processes - reduces the elevation of beaches and dunes. This in turn reduces the ability of coastal barriers to dissipate storms. Knowledge of changing coastal features can provide insight into how hazardous and damaging approaching storms may be in the future.
“We make measurements of the elevation of the dune along the beach and then we can compare that to the elevations of the hurricane-induced water levels. We do this along the coast and then we can create maps of how a beach might respond during a storm.”
Scientists are implementing a wide range of analytical methods such as ground surveys, aerial photography, modeling of waves and seafloor morphology, and lidar imagery to measure coastal vulnerabilities and predict how coasts will respond to hurricanes. By studying the impacts past storms have had along the Gulf and Atlantic coasts, scientists are working to forecast coastal hazards and future risk.
“One technology that has revolutionized what we do is called airborne LIDAR that stands for ‘light detecting and ranging’. It’s a laser aboard an airplane that flies over the Earth’s surface and it fires that laser at the Earth’s surface. Each beam of light reflects back to the aircraft. And they measure the incredibly short amount of time between firing the beam and receiving it back in the aircraft. With Global Positioning System aboard the aircraft, you can put together a map of the land surface. We depend upon this kind of technology now both to measure what the beaches and barrier islands look like before storms and after storms. Then compare the two surveys, and figure out how much the land has eroded, where new inlets have cut through barrier islands, where the houses are down. It’s an incredible data source for us.”
These multiple sources of information are used with mathematical models of likely wave height and storm surge for varying levels of hurricane strength, to help identify areas vulnerable to extreme coastal change.
“For example, we can model what happens when a Category 3 storm comes ashore in the Tampa Bay area of Florida. These arrows represent the wind direction for the storm. In this image we model the water levels or the elevations of storm surge. In this picture you can see the wave height as the storm comes ashore. These yellows and oranges represent the higher waves. As the storm progresses and storm surge increases, the city of Tampa goes under water and Pinellas County becomes two islands. As the storm passes, water levels recede.”
Knowing the hazards from extreme storms and vulnerabilities to erosion is essential for all coastal populations and for those in communities that are likely to accommodate evacuees. Maps and other information regarding approaching hurricanes are posted on the Coastal Change Hazards Program website 24 to 36 hours prior to landfall, to inform the public of areas most vulnerable to coastal changes during the storm.
You can learn more about coastal change hazards and USGS science at usgs.gov. Thanks for tuning in. The Coastal and Marine Geology Podcast is produced in St. Petersburg, Florida, and is a product of the U.S. Geological Survey, Department of the Interior.
Title: In Harm's Way: Measuring Storm Impacts to Forecast Future Vulnerability
This video podcast looks at the science behind understanding coastal vulnerability and hazards posed by extreme storms. It documents how USGS scientists study the response of coastal environments to the extreme winds, waves, and currents brought by such storms.
Location: St. Petersburg, Fl, USA
Date Taken: 8/25/2010
Video Producer: Matthew Cimitile , U.S. Geological Survey
Note: This video has been released into the public domain by the U.S. Geological Survey for use in its entirety. Some videos may contain pieces of copyrighted material. If you wish to use a portion of the video for any purpose, other than for resharing/reposting the video in its entirety, please contact the Video Producer/Videographer listed with this video. Please refer to the USGS Copyright section for how to credit this video.
Additional Video Credits:
Betsy Boynton (animation, graphics & music), Allie Wilkinson (editing), Ann Tihansky
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