Do we need to retrench, pull back from the coasts because of sea-level rise or rebuild differently? Where do we go from here?
We need an integrated approach that covers three areas: engineering, ecologically based adaptation and policies. Let's take engineering. There is a whole spectrum of engineering approaches, like innovative designs for subway grates. Right now we have open grates. We need to design and implement grates that close. We need to see what we can do with the tunnels, which is much more challenging. We need to think about drains. Some of those are innovative engineering solutions, some involve standards and regulations, like building culverts to withstand more drainage.

At the other end of the engineering spectrum is tidal barriers. What we recommended on that issue is: it needs to be studied. We need to begin the next set of feasibility studies: a significant study of the costs, benefits, feasibility in our New York coastal estuary, and the economic, environmental and societal costs and benefits. There is a lot of cost involved in creating such a big, engineered structure. There would be environmental changes we would need to understand. On the societal side: Which areas are protected? Some would be, some would not be, and how do we deal with the communities in different places?

The second part is ecologically based adaptation. There are the wetlands [that can absorb] coastal flooding, but there is also inland flooding. We also coexist with a wonderful, mixed deciduous and evergreen forest here. How can we coexist with a forest ecosystem in more effective ways, because of the damage caused by trees falling into power lines or trees falling into houses? Then again, having forested areas is good in terms of absorbing storm water. How can we really develop ecosystem-based adaptations that are effective for our region?

The third area is design and policy. Right now, what we call the societally acceptable level of risk is basically the one-in-100-year storm. Sandy was a wake-up shout for us all to think about: Is that the right level or do we need to change that? Is it really now the one-in-500-year storm? Or, as in Europe, is it even more?

Then there's coastal communities. Can there be a reduction in insurance premiums for homeowners who take adaptive measures? That's an incentive for doing a better job.

Overarching all of this is design, urban planning. What we really need to do is recover, rebuild and create a vibrant and sustainable coastal city region.

Let's do this in creative ways. For example, the Dutch are not just looking to engineering solutions, they are looking at a mix of solutions. So there are the iconic floating houses but they are also doing a lot with raising apartment buildings and allowing water to slosh in and out when floods come. We have to accept that we are a coastal region. There are going to be coastal floods. How do we live with it?

Is there enough room in New York City for things like wetlands to make a significant impact?
We have about 1,500 miles [2,400 kilometers] of coastline in the estuary. One of the things we need to do is see what areas are available to restore or maintain or reconstitute. The [New York City Department of Environmental Protection] has already started that with the Bluebelt Program [preserving wetlands for storm water management in Staten Island]. How did those work during Sandy? It was a very large storm. Did they work for a certain amount of time or up to what level of flooding? What's the potential for expanding those areas?

5 Comments

1. 1. drafter 11:11 AM 11/9/12

   In order to make the subway system impenetrable from ocean flooding would cost a fortune and would probably still leak so the best bet is often to let it flood and not use it for those few days. About dealing with the other surface waters from ocean flooding you can not build a drainage system big enough to deal with the onslaut so either make all the buildings 20 feet in the air to let the water flow or build dikes all around the city all are very expensive ideas. It might be better to just move.

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2. 2. BruceWMorlan 04:27 PM 11/9/12

   We clearly need to dissuade people from building and rebuilding in areas that we cannot protect from rising sea levels, or we need to wall out the sea and be prepared for local systems failures - like the Dutch. A simple way to accomplish this would be to stop subsidizing bad choices through subsidized flood insurance and unregulated banking. A well-regulated bank should be able to require insurance that is priced by free-markets, since a free-market insurance company should be charging premiums that reflect their exposure. Unfortunately, we tend to expect government to cover the costs of bad choices, and we tend to prevent banks and insurance companies from adequately covering their risks.

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3. 3. Sisko in reply to BruceWMorlan 04:16 PM 11/12/12

   Agreed

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4. 4. Sisko 04:50 PM 11/12/12

   Notice that nowhere is it suggested that mitigation activities will lessen any harm to cities.

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5. 5. Dr. Strangelove 08:40 PM 11/13/12

   New Yorkers should learn from the Dutch. Holland is below sea level. The Dutch literally drained the North Sea to reclaim a land area many times bigger than New York city. There is an old Dutch saying "God created the world, the Dutch made Holland."

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