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USGS Finalizes Hurricane Sandy Preparations

This Science Feature can be found at: http://www.usgs.gov/blogs/features/usgs_top_story/usgs-finalizes-hurricane-sandy-preparations/

Hurricane Sandy Resources


***Updated: coastal change section edited from original, based on an updated assessment from October 29, 2012***

As millions of northeast residents bought water, batteries and food this weekend in preparation for Hurricane Sandy, USGS scientists, engineers, and technicians worked up and down the Atlantic Coast, deploying storm-surge sensors and maintaining real-time streamgages in preparation for Hurricane Sandy’s arrival.

Storm-Surge and Real-Time Sensors

USGS Storm-Tide Mapper, showing all data collected by the storm-surge sensors and the USGS streamgage network.

USGS Storm-Tide Mapper, showing all data collected by the storm-surge sensors and the USGS streamgage network.

Much of the work involved installing more than 150 storm-surge sensors along the Atlantic coast, from the mouth of the Chesapeake Bay to Massachusetts. These sensors, which measure water elevation every 30 seconds, augment an already robust network of coastal and inland streamgages in place to monitor water levels throughout the storm.

A USGS scientist installs a storm-surge sensor for Hurricane Rita in 2005, the first storm in which these sensors were deployed.

A USGS scientist installs a storm-surge sensor for Hurricane Rita in 2005, the first storm in which these sensors were deployed.

In addition, eight of the recently deployed sensors are Rapid Deployment Gages, which provide real-time information to help forecast floods and coordinate flood-response activities in affected areas. These real-time gages will complement the many near real-time streamgages already installed along rivers and streams.

All data collected by these sensors and the existing USGS streamgage network are available on the USGS Storm-Tide Mapper.

Working with various partner agencies such as NOAA, FEMA, and the U.S. Army Corps of Engineers, the USGS strapped the storm-surge sensors – typically about 1 ½ inches wide and a foot long – to piers, docks or other structures in the water expected to withstand the storm.

They record the precise time the storm-tide arrived, how ocean and inland water levels changed during the storm, the depth of the storm-tide throughout the event, and how long it took for the water to recede.

This information gathered will be used to assess storm damage, discern between wind and flood damage, and improve computer models used to forecast future coastal change.

Anticipated Coastal Change

Probabilities of collision, overwash, and inundation for Sandy for the Atlantic coast of Delmarva.

Probabilities of collision, overwash, and inundation for Sandy for the Atlantic coast of Delmarva.

Elevated water levels and waves during tropical storms can lead to dramatic coastal change of beaches and dunes. The USGS has completed an assessment of likely coastal-change impacts from Hurricane Sandy.

Nearly 91 percent of the coast along the Delmarva Peninsula is very likely to experience beach and dune erosion from the storm, while overwash is expected to affected more than  half of the shoreline, and 22 percent of the beaches are expected to experience inundation by waves and storm surge   In these areas, waves and storm surge transport large amounts of sand across coastal environments, depositing sand both inland and offshore, causing significant changes to the landscape.

Overwash, the landward movement of large volumes of sand from overtopped dunes, is forecasted for portions of the east coast with the projected landfall of the storm. The severity of overwash depends on the strength of the storm, the height of the dunes, and how direct a hit the coast takes.

Probabilities of collision, overwash, and inundation for Sandy for the Atlantic coast of New Jersey

Probabilities of collision, overwash, and inundation for Sandy for the Atlantic coast of New Jersey

The models show that along the New Jersey shore, 98 percent of the coast is very likely to experience beach and dune erosion, while 54 percent is very likely to experience overwash, and 9 percent to experience inundation.

It also indicates that on the south shore of Long Island, N.Y., including Fire Island National Seashore, 93 percent of the coast is very likely to experience beach and dune erosion, 12 percent to experience overwash, and 4 percent to experience inundation; the lower percentages of overwash and inundation in these areas is because of the relatively high dune elevations.

The impact of previous storms on sandy beaches along the mid-Atlantic Coast has made them increasingly vulnerable to significant impacts such as erosion.

Beaches and dunes often serve as the first line of defense for coastal communities against flooding and other hazards associated with extreme storms.

Probabilities of collision, overwash, and inundation for Sandy for the southern coast of Long Island

Probabilities of collision, overwash, and inundation for Sandy for the southern coast of Long Island

Any compromise to these features means that storm-related hazards are more likely to threaten coastal property, infrastructure, and public safety during a future extreme storm event.