Hurricane Sandy's historic pummeling of New York City did more than explode power transformers, flood subway tunnels and leave entire city blocks awash — it has forced officials to think about how to rebuild the growing city so that it can survive more extreme weather in the future.
In a press briefing today (Oct. 30), New York Governor Andrew Cuomo said that New York City must adapt to the reality of extreme weather patterns. Dikes, seawalls, flood-proofed buildings and restored wetlands or beaches are among options presented last year in a report called "Vision 2020: New York City Comprehensive Waterfront Plan."
"There has been a series of extreme weather incidents," Cuomo said. "That is not a political statement. That is a factual statement. Anyone who says there's not a dramatic change in weather patterns, I think is denying reality."
Cuomo also used his Twitter account to pose a tough question: "How do we redesign the system to make sure this doesn't happen again?"
No retreat, no surrender
The "Vision 2020" report said that there is "no one-size-fits-all solution for climate change" that can protect New York City's sprawling and diverse waterfront. But it did suggest that retreating from the waterfront is no longer practical for much of New York City — especially as the city tries to support sustainable, dense development for a growing population.
The challenge of protecting New York City's existing waterfront gets even trickier when taking into account that much of lower Manhattan and elsewhere represents artificially expanded land that goes beyond Manhattan Island's original shape. Most of those areas, such as Battery Park City on the Hudson River, ended up being flooded by Hurricane Sandy. [ Sink or Swim: 6 Ways to Adapt to Climate Change ]
Mayor Michael Bloomberg described Hurricane Sandy as a "devastating storm" that was "maybe the worst we have ever experienced," during a briefing at the Office of Emergency Management in Downtown Brooklyn on Oct. 30.
"MTA CEO Joe Lhota has described this as the worst disaster the agency has seen in the 108 years the subways have been running," Bloomberg said. "And ConEd has described the damage done to its power systems as unprecedented in scope."
Learning to adapt
But the city does have ways to adapt, according to the "Vision 2020" report. New buildings can be built with flood-proofed materials and designs to withstand floodwaters, as well as raised living spaces and critical building systems above expected flood levels. Older buildings can also be retrofitted.
The building-by-building approach costs less up front than a new levee or flood barrier. But a mix of new protective barriers — such as hard seawalls or "soft edges" that reduce the speed of incoming waves — can also cushion the city against future storms similar to Hurricane Sandy.
Dikes, levees and floodgates can add to New York City's defenses by shielding large areas from storm surge. Farther out, artificial structures such as breakwaters or natural barriers such as wetlands, reefs, barrier islands and beaches can help soften the blow.
But for such a huge city, change will not be easy. Officials have known since the early 1990s that subways, tunnels and airports were at risk for the sort of flooding that Sandy caused, based on Army Corps of Engineers analyses.
Readying for the next big one
Officials must first understand the resilience of each part of the city's waterfront — a big problem until recently because they lacked accurate data about the elevation of coastal land and buildings. But the city made an effort to use LiDAR (Light Detection And Ranging) to more precisely map the city's elevation based on bouncing thousands of laser pulses off the ground from an aircraft flying overhead.
New York City also plans to update its hurricane evacuation zone maps based on updated information from the National Weather Service's Sea, Lake and Overland Surges from Hurricanes model. The Office of Emergency Management aimed to finish that revision by 2013, according to the "Vision 2020" report.
"There is no weather pattern that surprises me now and I think that's the attitude we have to take," Cuomo said.