Tuesday, July 25, 2017

Erosion creating growing threat for Cape Cod towns (WCVB)

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Erosion creating growing threat for Cape Cod towns

Scientists use drones to map shrinking dunes

WCVB Updated: 8:09 PM EST Feb 16, 2017

A series of recent nor’easters has led to beach erosion and caused structural damage on Cape Cod.

According to the Cape Cod National Seashore, storm damage included “the loss of stairs at Marconi Beach, damage to the stairs at Nauset Light Beach in Eastham and substantial damage to the Herring Cove Beach north parking lot in Provincetown.”

Seashore officials suggested the erosion is accelerating.

They said staircases that used to require replacement every 4-5 years now must be rebuilt every year.

The Town of Sandwich said waves have eaten away 10-15 feet of the dune it installed, after even worse erosion two years ago.

David DeConto, Assistant Director of Natural Resources, said the erosion could pose a damage to the town’s center within 2-3 years.

“Eventually, what happens is the dune will disappear and then the downtown area will be subject to flooding all the time,” DeConto said.

DeConto said town officials believe a jetty that protects the entrance to the Cape Cod Canal is blocking ocean currents that used to rebuild the dunes naturally during the summer.

He said he expects an ongoing study will confirm the theory and help convince the federal government to pay millions of dollars for the dredging and relocation of 400,000 cubic yards of sand.

Scientists from the U.S. Geological Survey have been tracking this winter’s beach erosion more closely than ever before.

They have been flying drones about 400 feet above the dune in Sandwich so they can map its shrinking profile.

“(The drone) can fly lower and slower and come right after a storm or right before a storm. So we can get a lot more detail, sort of on demand,” said Jon Budreski, of Airshark, a contract company hire to assist with the drone flights.

Chris Sherwood, of the U.S. Geological Survey, said the goal of the mapping is to create a model that can predict how much beach will be lost during a particular, perhaps down to the foot.

Officials would use such forecasts to warn beachfront homeowners when their property might be at risk.

“They do that now for tornadoes. They have an estimate of how much structural damage they might get. So this is kind of a similar thing for the ocean,” Sherwood said.

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