(Corrects spelling of "Corps," paragraph five)
By Zachary Fagenson
JACKSONVILLE BEACH, Fla., Sept 3 (Reuters) - Just months after the U.S. Army Corps of Engineers completed a $16 million project to restore sandy beaches in Jacksonville, Florida, Hurricane Dorian is about to pound them again, illustrating the uphill battle that American coastal cities face in protecting their most valuable asset.
The hurricane, which has already caused devastation and at least five deaths in the Bahamas, is forecast to cause some erosion at about 80 percent of the sandy beaches between Florida and North Carolina as it curves northward this week, according to the U.S. Geological Survey.
That figure is similar to forecasts ahead of other past major hurricanes in the region, and some of that erosion will be temporary: Sand that gets swept offshore in a storm is slowly returned to the beach in the following weeks in gentler weather.
But dunes, which are often the last buffer between the ocean and coastal buildings and infrastructure, can take months or years to naturally recover from damage.
"It's a natural process, but obviously with a hurricane it kind of speeds that up," Rick Powell, the 48-year-old owner of a marine construction company, said in an interview in Jacksonville Beach, Florida. His company is building a pier on the beach, and he admired the recent handiwork of the Army Corps of Engineers: "It's a shame because the dunes have never looked better."
Sandy beaches are a prime tourist draw in Florida. The land behind them has become increasingly valuable and developed over the last century, requiring elaborate efforts to stop the coastline from changing too much through natural erosion brought about by storms and rising sea levels caused by climate change.
Most of that work has been done by the Army Corps of Engineers, which has been carrying out "beach nourishment" projects since the 1950s. The projects involve adding tons of extra sand to beaches, increasing the protective buffer for the land behind.
The Army Corps' recently finished project around Jacksonville included restoring the dunes damaged by Hurricane Matthew in 2016 and Irma a year later.
As with all such projects, it is designed to be eroded during a storm, dissipating a storm's energy and protecting the city behind. The Army Corps says the costs of the projects are far outweighed by the potential cost of the damage they prevent happening.
Still, beach renourishment is a piecemeal effort. Florida's Department of Environmental Protection says that nearly half of its beaches, about 400 miles (640 km), are critically eroded.
"There's a not a whole lot you can do preceding a storm event like this," Kara Doran, a scientist at the U.S. Geological Survey's coastal science center in St. Petersburg, Florida, said in a telephone interview. Dorian's huge size and slow crawl toward the U.S. mainland only worsens the problem, she said, with damaging storm waves eroding the beaches for days at a time.
The USGS forecast that Dorian could send water surging over up to a quarter of the dunes in Florida and nearly 60 percent of the dunes in Georgia and South Carolina. "The dunes, once they erode, take decades to build back up," Doran said.
Chris Condon, 51, has lived in Jacksonville Beach for seven years, and says previous hurricanes have taught him that a first priority is "to shore up the dunes.
"They're building up the dunes," he said, "closing up the entrances and making sure that there's no big gaps for the water to run through and get into the neighborhoods." (Reporting by Zanchary Fagenson; additional reporting by Jonathan Allen in New York; Editing by Scott Malone and Jonathan Oatis)
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