Sponge Parks, Sand Dunes May Boost Resilience to Storms

Sea Bright after Sandy
A view of structures demolished by Hurricane Sandy in Sea Bright, on Nov. 20, 2012. Along the Jersey ocean shoreline structures that were built on the beach without the protection of dunes or bulkheads sustained the worst damage. Better-protected structures may have flooded but many suffered little structural damage. Photographer: James S. Russell/Bloomberg

A couple of years ago, I walked along a flood-protection wall in the oceanfront New Jersey town of Sea Bright and wondered how severe weather would affect it. Now I know.

Photos show waves overtopping the wall and sweeping through the streets of the town, very close to where Hurricane Sandy made landfall on Oct. 29.

Ripping apart seaside communities is just one way that storm took its toll. The variety and enormous geographic extent of the destruction will require us to think hard about how to protect communities against future disasters.

Beyond the coastline damage of Sandy, we must look at how to protect rail and road tunnels from flooding and how to strengthen the electrical infrastructure -- whether in flood-prone underground vaults or the thousands of square miles of overhead lines in suburbs. How will we fortify airports and avoid evacuating low-lying hospitals?

We have to ask now, because decisions that are currently being made will affect how well rebuilt neighborhoods and infrastructure will withstand the next major storm.

Dodging Costs

Many cities and states have drawn up plans to increase resilience to catastrophes, but there has been little impetus to act on anything that’s costly or requires complex negotiations.

The obvious answer is to build higher sea walls along the ocean coast or around Lower Manhattan. In New York City there’s long been talk of a massive storm-surge barrier outside the Verrazano-Narrows Bridge. These are investments of at least hundreds of billions of dollars.

I don’t think the U.S. is willing to spend that kind of money.

Resilience thinking helps us choose solutions that protect us while delivering other benefits that make large investments worthwhile.

Rebuilding natural dunes is a “soft” path to coastal restoration. The dunes repel waves and feed the beach with sand. Many shorefront owners will demand higher seawalls, which is the “hard” path, and it has drawbacks.

Engineered fortifications also destroy the beach ecology and the amenity that draws people and creates jobs. Seawalls can induce permanent loss of beach sand, requiring even higher walls. For that matter, dune building isn’t foolproof; dunes slowed Sandy’s surge but didn’t stop extensive flooding.

Land Devalued

In New York, high walls (20 feet minimum) would obliterate waterfront parks and promenades that have proven immensely valuable. The walls would devalue billions of dollars of park and neighboring investments.

Many cities are experimenting with rain gardens, storm-water-retention wetlands, and a variety of other devices that fill up with water during storms so that the drainage infrastructure is not overwhelmed. Making landscapes resistant to floods (note the lack of long-term damage to New York city waterfront parks) is generally cheaper than building high walls.

I looked back on resilience work designed for a Museum of Modern Art exhibition two years ago, called “Rising Currents.” It now seems prophetic.

Among the proposals by Susannah Drake of landscape-architecture firm Dlandstudio and Stephen Cassell of Architecture Research Office was the “Sponge Slip,” which would have replaced a Lower Manhattan parking lot with a sunken park. The idea was to guide floodwaters into the park basin and away from the subway tunnels and electrical infrastructure that Sandy crippled.

What seemed a pipedream then seems a no-brainer today.

Other Tools

It may be too expensive to save some neighborhoods. Then citizens must think about moving individual structures or perhaps entire neighborhoods out of harm’s way.

Land-use tools, rarely considered in disaster contexts, can help. Land readjustment, used in water-soaked Holland, lets owners collectively redraw their property lines to create greater value through more efficient development patterns, while shifting development away from vulnerable areas.

These choices aren’t simple. In a few months the urgency of building for resilience may well fade, and rebuilding in the same vulnerable way is the path of least resistance. We must keep in mind that the next Sandy or Katrina awaits.

(James S. Russell writes on architecture for Muse, the arts and culture section of Bloomberg News. He is the author of “The Agile City: Building Well Being and Wealth in an Era of Climate Change.” The opinions expressed are his own.)

Muse highlights include Ryan Sutton on dining, Craig Seligman on books.