The Netherlands, for example, is planning for nearly a meter of sea level rise by the end of the century, though that is at the high end of scientific projections. The Dutch plan is to both strengthen and heighten existing dikes and levees but also, as has been the practice for hundreds of years, to prepare certain areas as fail-safe flood zones, ready to be inundated when necessary.
In the future, preparing for such inevitable flooding will be as vital—if not more important—than attempting to prevent such events. "The chance that Manhattan will get another storm surge is higher and higher," Houser notes. Infrastructure—particularly that located below ground, such as subway tunnels and vital equipment—must be made flood ready. Basement generators or fuel tanks can be relocated, for example, and pumps in tunnels can be protected so they can later do their job of water removal.
That will help New York City face future superstorms, which could produce more flooding than Sandy. Fortunately for the metropolitan region, this post-tropical cyclone didn't dump rain on the same places where it dumped seawater. Where rainfall and storm surge combine, flooding will be even worse. "Some storms see a tremendous surge at the mouth of a river at the same time as a lot of rain," Rhome explains. "They can come together to produce incredibly damaging results."
In fact, the New York City flood zone maps, like similar maps for municipalities across the U.S., are a direct result of off-season computer modeling to see what could happen in the worst case. So, Zone A is likely to be inundated by any tropical cyclone strength storm in the region, while Zone C requires a major hurricane boasting winds above 110 mph. "Zone C is your worst case scenario," Rhome explains.
That is born out by hard experience here in the Zone C section of Gowanus, where even a typical northeastern rain storm produces sewage outflows into the canal and, in harder rains, can see local streets turn into rivers. Pair that with the kind of seawater surge that Superstorm Sandy produced and even more catastrophic flooding will occur. It's a future New York City—and all coastal cities—should be preparing for now. Superstorm Sandy's lesson, as New York State Governor Andrew Cuomo noted in a press conference on Halloween, is "the recognition that climate change is a reality, extreme weather is a reality. It is a reality that we are vulnerable."