Storm Surge Barriers May Save Wall Street, But Would Worsen Flooding in Outer Boroughs
After Hurricane Sandy the consensus both in New York City and in Albany is that there's a lot that needs to be done to prevent future devastation from extreme weather and climate change.
It's tempting to think that erecting storm surge barriers—such as London has done with the Thames Barrier—could protect the Manhattan, but as Catherine Seavitt Nordenson, associate professor of landscape architecture at the City College of New York, points out, saving Wall Street from future flooding in this way would just make flooding in outer boroughs worse.
Prof. Seavitt says:
If you mitigate to protect Lower Manhattan, you increase the impact in other areas. Everyone outside the surge protection zone would be in jeopardy because the water doesn't get reduced, it just goes someone else. It's an environmental justice issue.
A better way to go about protecting New York City, Prof. Seavitt says is, in addition to hardening critical infrastructure against flooding, to work to improve soft infrastructure, taking cues from nature to change coastal edge of the city to be more naturally resilient—something she and her team have long proposed.
In a 2010 report Seavitt's team proposed:
Restoring and enlarging wetlands, creating reefs and archipelagoes of artificial islands, and seeding oyster beds. Spoils from harbor dredging and deepening, which is regularly performed by the US Army Corps of Engineers, could be used for these beneficial purposes.
Reefs and wetlands would mitigate destruction by absorbing water and dissipating wave energy. Archipelagoes of small, artificial islands would weaken wave energy in the water column. Oysters and other mollusks would biologically filter and help cleanse the water.
Other techniques proposed include extending now abandoned piers to allow water to enter flood zones in a more controlled way and minimize damage of flooding that does occur.