Forecasting Coastal Change Prior to Hurricanes Takes Leap Forward

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When the next hurricane heads toward a coastal community in the United States, residents and emergency managers busily readying for the storm will have a new resource available to help them better understand what to expect – a detailed forecast of how the storm may change the coast.

When the next hurricane heads toward a coastal community in the United States, residents and emergency managers busily readying for the storm will have a new resource available to help them better understand what to expect – a detailed forecast of how the storm may change the coast.

Fire Island, New York, prior to Hurricane Sandy
An image showing the USGS coastal change forecast for Fire Island, New York, prior to Hurricane Sandy, with a photo inset showing what actually happened. The USGS forecast accurately called for extensive dune erosion along the entire island as well as several large areas of overwash. The location of a breach in the island was also successfully forecast.

Is the sand below houses likely to erode? Are evacuation routes potentially going to be covered with sand? What’s the probability water may inundate portions of a community? Is the barrier island you live on likely to breach?

For the past several decades, the U.S. Geological Survey has been refining its ability to describe how coasts respond to extreme storms. More recently – since 2011 -- the agency began using its ever evolving modeling efforts to begin forecasting the probability of coastal change prior to significant storms, providing key information to community and emergency planners before the storm arrived.

This year, for the first time, forecasts will provide the full assessment of probabilities of coastal change, along with information on dune elevations and how high water levels may reach during a storm. The information, which is integrated with information from NOAA, will all be easily accessible on the USGS Coastal Change Hazards Portal.

The additional information and tools available on the portal will help emergency managers, coastal planners, and community leaders, who can combine the information found on the portal with other data to identify where hazards pose the greatest risks to their communities, allowing them to develop specific plans of action before a storm’s landfall.

“We’re very excited about this new capability. As a storm approaches the coast we will be able to make timely forecasts of coastal change based on models that show how storm surge and high waves will affect beaches, and identify where the greatest threats are for erosion, overwash, or even inundation or breaching of coastal areas,” said Hilary Stockdon, a USGS research oceanographer and head of the National Assessment of Coastal Change Hazards extreme storms project. “As the storm’s landfall location becomes more certain and the wind and wave conditions change, the forecast is updated to provide more accurate information on what to expect in terms of coastal change.”

 USGS Coastal Change Hazards Portal
An image of the USGS Coastal Change Hazards Portal showing the data and products available for Tropical Storm Erika had it made landfall in August 2015. The Portal is a comprehensive resource that includes climate-related and extreme event observations, forecasts, visualizations and information on historical coastal changes.

Through the Portal

The expansion of the USGS Coastal Change Hazards Portal provides visitors to the site the ability to track waves and storm surge that can lead to coastal change, and view maps that display a more accurate picture of the many coastal hazards posed by an approaching storm.

This comprehensive online resource includes climate-related and extreme-event observations; forecasts; visualizations and information on historical coastal changes. It also provides the ability to explore coastal-hazard risks at varied scales, from a local area to a regional or national perspective. This location-specific capability is extremely valuable for planning, preparedness and for making decisions to improve coastal resilience.

Image: Coastline Breach
A breach in the coastline of Rodanthe, North Carolina, caused by Hurricane Irene in 2011. Repeated storm impacts, combined with sea level rise, make the development and improvement of models that help forecast coastal change very important to planners working to build more resilient communities. USGS photo by Karen Morgan.

 

“Forecasting coastal change that will occur during tropical storms and hurricanes is getting more and more accurate,” said Stockdon. “As Hurricane Sandy was making landfall, we were able to forecast the locations of several barrier island breaches as well as extensive areas of overwash. This type information gives local emergency officials and coastal planners a good idea of what to expect before the storm arrives. Ultimately, our goal is to provide good science and easily accessible tools that will support the efforts of federal, state, and local agencies working to make communities more resilient and to reduce the risk to both lives and property. This portal will help us do exactly that.”

Long-term research, combined with supplemental funds from Hurricane Sandy recovery work, has allowed the expansion of the portal. Since Hurricane Sandy in 2012, work with NOAA and the U.S. Army Corps of Engineers has contributed to expanded forecasting capabilities of regional-scale storm hazards that are delivery by the Portal.

USGS Coastal Change Hazards Portal
An image of the USGS Coastal Change Hazards Portal on a mobile device. The easy to use Portal provides visitors to the site the ability to track waves and storm surge that can lead to coastal change, and view maps that display an accurate picture of the many coastal hazards posed by an approaching storm.

How It Works

The coastal change forecasts are triggered by National Hurricane Center Advisories and combine wave and surge modeling from NOAA with detailed coastal elevation data provided by the USGS. The forecast will show if significant dune erosion is expected, where overwash is likely, and the likelihood of the beach and dunes being inundated with water.

While these models continue to improve understanding of extreme storm processes as well as the accuracy of assessments of storm-induced coastal change, the Portal also gives the public, scientists and coastal managers tools to visualize a range of coastal changes caused by major storms, sea-level rise and other long-term processes.

“The foremost objective of the USGS Coastal and Marine Geology research program is to provide timely information that leads reduced loss of lives and livelihoods,” said Susan Russell-Robinson, acting Program Coordinator. “The USGS is dedicated to developing capabilities and user-friendly tools that allow us to describe the relative vulnerabilities of U.S. coastlines to coastal change hazards in a nationally consistent way. By coordinating with partners and standardizing this research, we help make our nation and coastal communities not only more resilient to storms, but also to longer term impacts like sea-level rise.