Feds study Fire Island breach created by Sandy

The breach on Fire Island caused by superstorm

The breach on Fire Island caused by superstorm Sandy is seen looking north. (March 9, 2013) (Credit: Doug Kuntz)

Three federal agencies using high-tech devices and a decades-old retrofitted military vehicle last week mapped the floor of the new Fire Island breach, studied shoaling on either side and calculated how fast water is moving through the cut made by superstorm Sandy.

It's the first time the U.S. Geological Survey, National Park Service and Army Corps of Engineers have been able to document and study a breach in this region, said Cheryl Hapke, a Florida-based research geologist with the USGS St. Petersburg Coastal and Marine Science Center.

They used a former Army vehicle from the 1960s and a remote-controlled boat loaded with GPS technology, Doppler radar and other electronics to take measurements on land and water.

"This presents a really unique opportunity," said Hapke. "There has not been a breach in this area that remained open for years."

Fire Island was last breached in December 1992 when a storm made two new cuts. One was immediately closed, the other 10 months later after it had grown to 2,500-feet wide, according to Park Service documents.

Sandy created three new slices across Fire Island when it hit on Oct. 29. Two were closed, but a third in the Fire Island National Seashore wilderness area near Old Inlet was left open.

Measurements taken at the end of May show that the north side of the breach is 656 feet wide and the south portion is 1,266 feet wide. The width and depth have fluctuated since Sandy.

With sufficient warning about Sandy's path, USGS researchers went to Fire Island before the storm to take photos, map elevations and document the shoreline to compare before and after measurements. USGS scientists recorded the depth of the breach and speed of the water twice in November, but had not returned until last week.

"Ten times as much water is flowing through at peak times than in November," said Chris Schubert, a USGS supervisory hydrologist at Water Science Center in Coram.

They piloted a small, remote-controlled craft called a Q-boat into the breach, as they had in earlier trips. Resembling a red speedboat about 4 feet long with a covered top, the Q-boat held the GPS and Doppler technology to scan the water.

The scientists also had equipment loaded on a Lighter Amphibious Resupply Cargo, or LARC -- an Army Corps vehicle that can travel on land and float on water.

Data collected will help scientists create a 3-dimensional portrait of the breach, and study how the water is moving.

Hapke and other USGS scientists have been studying Fire Island National Seashore for years. "We know a lot about the system, but we've never had the opportunity to study a big storm," she said.

With Sandy, "about 50 percent of the island experienced overwash, a complete flattening of the dunes," Hapke said.

And the destruction kept coming. "The storms in the winter caused higher erosion than Sandy because the beach was low," Hapke said.

About 49 feet of beach, on average, washed away between October and April. The maximum lost in one spot was more than 208 feet, she said.

With calmer weather, the beach is replenishing. "We expect the beach is naturally building itself up," Hapke said.

The data collected by last week's research will help the National Park Service, which oversees the seashore, develop long-term management strategies, seashore spokeswoman Paula Valentine said. The Army Corps also may use the data if it is asked to close the breach, spokesman Chris Gardner said.

Suffolk County Executive Steve Bellone has called on the state Department of Environmental Conservation to close the breach because of concerns about flooding in communities along the bay. The DEC won't authorize the work unless it appears the breach isn't closing naturally.

Environmentalists say the breach is improving water quality in the Great South Bay. Researchers have documented higher levels of salinity in the bay, but no unique changes in tide levels.

 

 

STUDYING FIRE ISLAND BREACH

 

WHO: U.S. Geological Survey, Army Corps of Engineers and National Park Service

WHAT: water depth, water speed, tidal flow and shoaling (sand buildup) on either side of the breach

WHY: Data collected will help scientists create a 3-dimensional portrait of the breach, and study how the water is moving. Superstorm Sandy created three new slices across Fire Island when it hit on Oct. 29. Two were closed, but a third in the Fire Island National Seashore wilderness area near Old Inlet was left open.

Measurements taken at the end of May show that the north side of the breach is 656 feet wide and the south portion is 1,266 feet wide. The width and depth have fluctuated since Sandy.

Fire Island was last breached in December 1992 when a storm made two new cuts. One was immediately closed, the other 10 months later after it had grown to 2,500-feet wide, according to Park Service documents.

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