Community Corner

Retreat? Defend? Baltimore Faces Quandary in Sea Rise Problem


By Lauren Redding, Capital News Service


Engineers sum up Baltimore’s options for dealing with rising sea levels simply: The city can retreat or defend.

But many say that for Baltimore, a city with 61 miles of coastline, neither option is perfect.

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Retreating means relocating low-lying properties that are at risk for major flooding—not a likely move for Baltimore’s oldest neighborhoods. Defending means building a barrier, such as a seawall.

This year, Baltimore’s Disaster Preparedness and Planning Projectis updating the city’s emergency plans.  Officials say the debate between retreating and defending has already come up, among many ideas for dealing with rising sea levels.

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Most Baltimoreans have accepted that some areas will flood and buildings will need to be rebuilt, said Phil Lee, a civil engineer with the Baltimore office of the engineering firm Moffatt & Nichol and a member of the city’s Disaster Preparedness and Planning Project.

"Fells Point has been flooding for the last 100 years," he said of one of the city’s oldest communities, which flooded about 5 feet deep in Tropical Storm Isabel in 2003. "People just live with it. And they accept it, because they know they’re in a low level and it will occur more often.

"If you’re afraid of rising sea levels, either leave the area or make the area you live in higher," Lee said. "That means you would have to tear down all the buildings and make a new Fells Point."

Dr. Bilal Ayyub, an engineer who studies rising sea levels at the University of Maryland, said one of Baltimore’s options is to protect itself by building seawalls and floodgates or creating ecological structures, like wetlands and vegetation.

Seawalls are massive, vertical structures built to protect coastal land from heavy wave action and rising waters.

Usually made from poured concrete, steel sheets and concrete blocks, seawalls have been used for centuries. The Netherlands, a country where about a quarter of the land is below sea level, has used a system of dikes and levees since medieval times. At least 40 percent of Japan’s coast is protected by a seawall.

   

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But experts say there’s no one-size-fits-all solution, and what works in Asia and Europe may not work in the United States. Coastal U.S. cities from New Orleans to Washington and Hoboken, N.J., are also grappling with how best to prepare themselves for a rise in sea level of 1 to 5 feet over the next century.

Seawalls can cost millions to billions of dollars to build—so expensive, Ayyub said, that it might theoretically be cheaper for the city to purchase the at-risk land from businesses and homeowners, relocate the communities and turn the below-sea-level points into marshes or dunes.

For a city like Baltimore, which was settled because of its location on the water, that may be an unrealistic choice.

Ken Hranicky, Baltimore’s flood plain manager and member of the city’s disaster planning committee, said that while seawalls will be considered as an option, he doesn’t think they are a likely one.

Hranicky said it would be tricky for city planners to determine where and how high to construct the wall, especially since even climate change experts can’t agree on how high waters will rise in the future.

"How can you stick up any type of seawall when you have no idea how high the sea level is going to rise?" Hranicky said.

The same can be said for another option: floodgates—retractable gates that are closed during impending storm surges to stop flooding. Lee said additional concerns come with them—namely, you get little assurance they’ll work when it counts.

"You can automate it to have the walls come up, but that’s not idiot-proof,” Lee said. “When you need it, it has to come up. If there’s no electricity, how do you do it?"

While both floodgates and walls could protect Baltimore, massive construction may defeat the purpose of having a waterfront community, Ayyub and Lee said.

"A seawall would protect from storm surges, but then again, does everyone want to look at a wall?" Lee said. "Do we really want a touristy area where no one can see the harbor?"

And where exactly to put a seawall is unclear, Hranicky said. The Patapsco River branches before it reaches the Inner Harbor. That means there’s no single location for a seawall that would protect all of the waterfront.

Officials could choose to build a wall near the Inner Harbor to protect Harborplace and valuable tourism areas, or near Fort McHenry to protect the port.

But seawall placement in Baltimore poses ethical dilemmas as well, Hranicky said. Baltimore’s Cherry Hill, Brooklyn and Curtis Bay neighborhoods are far poorer than the booming, more affluent Inner Harbor developments.

"The city would be hard-pressed to put up a seawall just to protect our money while leaving (poorer communities) to protect themselves," Hranicky said.


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Several U.S. coastal cities are trying seawalls to defend against floods. New Orleans recently completed a 133-mile-long network of levees, walls and pumps for a total of $14.5 billion.

Engineers are touting it as a remarkable improvement from the original floodwalls and levees built 40 years before Hurricane Katrina. When Katrina hit in 2005, the weak barriers collapsed—making New Orleans an example what can go wrong when proper defense mechanisms aren’t in place.

After Katrina, officials at the Federal Emergency Management Agency reviewed flood maps nationwide to determine if cities were adequately prepared. The review deemed Washington lacking.

According to FEMA, sandbags and jersey barriers wouldn’t be enough if a massive storm caused the Potomac River and Tidal Basin to flood. In 2010, Washington started construction of $9 million worth of levees and walls around the National Mall to prevent flooding.

Hurricane Sandy’s floods stranded about 20,000 Hoboken, N.J., citizens for three days last October, leading Mayor Dawn Zimmer to propose a similar system to Washington’s with 10-to-15-foot-high walls.

Hoboken’s densely populated urban landscape calls for a different kind of flood mitigation plan than beach communities, which are able to build houses on stilts or add dune defense systems.

Ocean City, N.J., for example, spent the last 25 years building up its coast with hundreds of feet of artificial dunes. The weak dunes were wiped out within a few hours of battering by Sandy. The wider and higher dunes not only survived the storm but protected communities.

Rick Schwartz, author of Hurricanes and the Middle Atlantic States, said the coastal areas damaged by Sandy—and Baltimore in particular—should be prepared for more storms of that force.

Schwartz tracks historical hurricane patterns. Typically, he said, the Mid-Atlantic will see 30 to 50 years of relatively calm activity, followed by a 25- to 30-year-long period of intense hurricanes. Schwartz says the Mid-Atlantic entered a period of increased activity in 2011, right after Hurricane Irene.

"Baltimore is firmly in the hurricane belt of the Mid-Atlantic," Schwartz said. "It wouldn’t surprise me to see something worse than (Hurricane) Isabel in the next 25 years, and maybe more than once."

But Schwartz said Baltimore should have started discussing seawalls and other defenses in 2003 after Tropical Storm Isabel.

"We have to accommodate Mother Nature’s bad moods," he said. "It’s going to take innovation. It’s going to cost money. Each area is very different, each area has to determine its particular vulnerability. There’s no one solution for everyone, but we’ve got to do something."


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