Washington, D.C., would not have suffered as badly as New York City if Superstorm Sandy had thundered down on the capital, a recent study found.
In such a scenario, the city’s parks along the Potomac and Anacostia rivers would absorb substantial amounts of floodwater, and numerous levees and other structures, like the 17th Street levee closure, would break storm surge.
"I think we all expected this scenario to turn out worse than it did," said Jason Elliott, senior service hydrologist at the National Weather Service, who measured Sandy’s effects on D.C. "Certainly, it’s possible something worse than this scenario could happen — but this is a plausible case that can be used for preparedness, and gives hints that Isabel in 2003 wasn’t the worst possible event."
Sandy generated such big waves that it’s still making headlines almost 2 ½ years later. New York’s infrastructure was not prepared for such a powerful storm — subways flooded, houses were swept away and 53 people were killed in the state as storm surge and strong winds battered the Northeast coastline. States paid more than $50 billion to repair the damage, according to the National Hurricane Center.
The storm also was a turning point for policy in the worst-hit states.
"Our climate is changing," New York’s then-mayor, Michael Bloomberg, wrote in an editorial for Bloomberg View at the time. "And while the increase in extreme weather we have experienced in New York City and around the world may or may not be the result of it, the risk that it may be — given the devastation it is wreaking — should be enough to compel all elected leaders to take immediate action."
Since the disaster, hurricane warnings have been revamped, and more detailed risk evaluations have been developed. Some states have begun reshaping their coastline to break storm surges, as part of an effort to prepare for stronger storms expected with climate change.
When Hurricane Isabel hit D.C. in 2003, it reached a record water level of 8.1 feet, the research found. Comparatively, Sandy-triggered water levels reached 9.3 feet in the Battery at the tip of Manhattan and 12.6 feet at Kings Point.
Elliott and local, state and federal agencies formed a team called Silver Jackets to look at how the capital would cope with an event like Sandy and what adaptation work was necessary. They found that though the World War II Memorial was designed to absorb floodwaters, flooding would still cover the Jefferson Memorial, as well as the Roosevelt and Martin Luther King Jr. memorials. Reagan Washington National Airport’s runways and the Waterfront Metro station would also be underwater.
Still, Washington would not suffer as heavy a toll as New York City. The city would not need to evacuate people as floods would primarily affect monuments and parks — at least according to a current scenario. Sea level rise could change the situation.
"Sea-level rise is the real concern, more than Sandy," said Adam Sobel, a professor at Columbia University who wrote a book about Sandy. "Rather, it was clear that sea-level rise was the most certain source of climate change influence in the disaster that Sandy caused, and remains perhaps the most worrisome long-term future risk for NYC and many other coastal cities."
Around New York City, water levels have risen 1.5 feet since the mid-19th century, contributing to the devastating effects of Sandy-related flooding. Globally, water levels are expected to rise approximately 10 inches to several feet by 2100, and in D.C. they have already risen by 6 to 8 inches since 1960.
Higher water levels make it easier for storm surges to inundate cities if buildings are not raised.
Prior studies helped New York
Elliott’s study did not account for how Sandy would affect D.C. as sea level rises in the coming century. It’s likely that the flooding scenario would be worse if a storm occurred on top of higher water levels.
But studying Sandy’s potential effects is still important, said Sobel. Scientists had been working on predicting the effects of strong storms in New York City for years, and those studies helped the city brace for Sandy, he added.
Bloomberg and city officials ensured subways were closed, emergency shelters were prepared and efforts to evacuate vulnerable areas were made before the storm hit.
"What didn’t go well was the things that couldn’t be done at the last minute," Sobel said. "You can’t make system changes in a week."
Changes to infrastructure, like better flood barriers, storm surge protection and regulations for higher buildings, would have dampened Sandy’s effect. But these strategies were primarily put into place after the disaster, and many say more work needs to be done to improve the city’s resilience.
Now that cities know how bad the storm was, however, they can prepare for similar events far in advance. In D.C., the Silver Jackets team is looking into developing more accurate inundation maps for better preparedness.
"Things are going in the right direction," Sobel said. "Sandy, like many extreme weather events, served to make people remember that we are vulnerable to what the atmosphere delivers. Understanding that in a visceral way is the first step toward any climate action."