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October 29, 2012 Hurricane
USGS Storm-Surge Sensors Deployed Ahead of Tropical Storm Sandy
RESTON, Va. -- Storm response crews from the U.S. Geological Survey are installing more than 150 storm-tide sensors at key locations along the Atlantic Coast -- from the Chesapeake Bay to Massachusetts -- in advance of the arrival of Tropical Storm Sandy.
Working with various partner agencies such as NOAA, FEMA, and the U.S. Army Corps of Engineers, the USGS is securing the storm-tide sensors, frequently called storm-surge sensors, to piers and poles in areas where the storm is expected to make landfall. The instruments being installed will 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.
"In the hours and days before Irene made its epic sweep up the eastern seaboard last year, USGS deployed a record number of storm-surge sensors that yielded important new information on storm tides along some of the most populated coastline in the United States," said USGS Director Marcia McNutt. "Now with Sandy we have the opportunity to test and improve predictive models of coastal zone impact based on what we previously learned."
Storm-tides are increases in ocean water levels generated at sea by extreme storms and can have devastating coastal impacts. In locations where tidal forecasts are known, the sensors being installed can also help determine storm surge. For differences between storm-surge and tidal-surge, visit the National Hurricane Center's website.
This information will be used to assess storm damage, discern between wind and flood damage, and improve computer models used to forecast future coastal inundation.
In addition, rapid deployment gauges will be installed at critical locations to provide real-time information to forecast floods and coordinate flood-response activities in the affected areas. The sensors augment a network of existing U.S. Geological Survey streamgages, which are part of the permanent network of more than 7,500 streamgages nationwide.
Of the sensors deployed specifically for Sandy, eight have real-time capability that will allow viewing of the storm-tide as the storm approaches and makes landfall. Besides water level, some of these real-time gauges include precipitation and wind sensors that will transmit all data hourly. All data collected by these sensors and the existing USGS streamgage network will be available on the USGS Storm-Tide Mapper link atwww.usgs.gov/hurricanes.
Providing information to support future forecasts could ultimately save lives during future storms. These sensors were deployed for the first time during Hurricane Rita in 2005. Before then, scientists had limited data available to study the effects of storm surge.
"Forecasters at the National Weather Service rely on USGS real-time and long-term data to improve storm surge models and prepare storm-tide warnings," said Brian McCallum, assistant director of the USGS Georgia Water Science Center, who is helping coordinate the sensor installation effort. "Floodplain managers, federal, state and local emergency preparedness officials, emergency responders, scientists and researchers all benefit from the storm-tide and associated flood data. It’s useful for flood damage prevention and public safety."
The USGS studies the impacts of hurricanes and tropical storms to better understand potential impacts on coastal areas. Information provided through the sensor networks provides critical data for more accurate modeling and prediction capabilities and allows for improved structure designs and response for public safety.
The USGS also continuously monitors water levels and flows at thousands of the nation's streams on a real-time basis. The public can access this information for their area at the USGS Current Streamflow Conditionsweb page. Also, USGS WaterAlert allows users to receive a text or email from the USGS when waters are rising in rivers and streams near them.
Sandy to Erode Many Atlantic Beaches
ST. PETERSBURG, Fla. – Nearly three quarters of the coast along the Delmarva Peninsula is very likely to experience beach and dune erosion as Hurricane Sandy makes landfall, while overwash is expected along nearly half of the shoreline.
The predictions of coastal change for the Delaware, Maryland and Virginia peninsula is part of a larger assessment of probable coastal change released by the U.S. Geological Survey Friday.
"Model forecasts are run anew for each hurricane, as each case has unique factors in terms of storm intensity, timing with respect to tides, angle of approach, and must account for ever-changing details of coastal dune configuration," said USGS Director Marcia McNutt. "These models help us understand where emergency management resources might be most needed."
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.
“On the Delmarva Peninsula, near the storm's expected landfall, close to three quarters of the sandy coast is expected to see beach and dune erosion. Fifteen percent of the coast is very likely to be inundated by waves and storm surge,” said USGS Oceanographer Hilary Stockdon from the USGS St. Petersburg Coastal and Marine Science Center.
In these areas, waves and storm surge would transport large amounts of sand across coastal environments, depositing sand both inland and offshore and causing significant changes to the landscape, Stockdon noted.
The models show that along the New Jersey shore, 81 percent of the coast is very likely to experience beach and dune erosion, while 7 percent is very likely to experience overwash. It also indicates that on the south shore of Long Island, N.Y., including Fire Island National Seashore, 43 percent of the coast is very likely to experience beach and dune erosion. Overwash and inundation are not expected in these areas because of the relative high dune elevations.
According to USGS geologist Cheryl Hapke, many of the sandy beaches along the mid-Atlantic Coast have become increasingly vulnerable to significant impacts such as erosion because of past storms, including Hurricanes Ida (2009) and Irene (2011), as well as large northeastern storms in 2005 and 2007.
“Beaches and dunes often serve as the first line of defense for coastal communities against flooding and other hazards associated with extreme storm” said Hapke, “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.”
Beach and dune erosion occurs when storm surge and waves collide with the base of a dune, termed collision in the model, and wash away significant amounts of sand. Overwash happens when these forces exceed dune height and move sand inland. Inundation is a process by which an entire beach system is submerged and, in extreme cases, can result in island breaching.
The USGS coastal change model forecasting likely dune erosion and overwash from the storm can be viewedonline.