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Not so fast on levees and seawalls for NY harbor?

- November 2, 2012

I was talking with June Williamson and mentioned offhand that I’d seen something in the paper saying that if only we’d invested a few billion dollars in levees we would’ve saved zillions in economic damage from the flood. (A quick search also revealed this eerily prescient article from last month and, more recently, this online discussion.)

June said, No, no, no: levees are not the way to go:

Here and here are the articles on “soft infrastructure” for the New York-New Jersey Harbor I was mentioning, summarizing work that is more extensively published in two books, “Rising Currents” and “On the Water: Palisade Bay”:

The hazards posed by climate change, sea level rise, and severe storm surges make this the time to transform our coastal cities through adaptive design. The conventional response to flooding, in recent history, has been hard engineering — fortifying the coastal infrastructure with seawalls and bulkheads to protect real estate at the expense of natural tidal wetlands and ecosystems. This approach has been proven environmentally damaging, unsustainable, and often ineffective. The failure of levees and other coastal protection structures facing Hurricane Katrina in 2005 is a dramatic example of infrastructural inadequacy. The unexpected ecological effects of the Eastern Scheldt Storm Surge Barrier in the Netherlands also indicate the risky nature of such systems. . . .

We propose three adaptive strategies to transform the Upper Bay, to reduce flood risk from both sea level rise and storm surge, and to challenge current functional relationships among water, land, and shelter.

Create an archipelago of islands, shoals, and reefs in the Upper Bay to both reduce the impact of storm-induced wave energy and improve the ecology of the estuarine environment. The bathymetrics of the bay will be modified, but current shipping channels will be maintained.

Create a soft but resilient coastal edge, combining tidal marshes, public parks, and finger piers and slips for recreation and possible development, and determine where to selectively place protective seawalls.

Create flexible and democratic zoning formulae for coastal development that evolve in response to climate change and storm events to increase community welfare and resilience to natural disasters. . . .

There is also this piece, just published on “Urban Omnibus,” the blog of the Architectural League of New York, that includes a decent summary of the green or soft infrastructure argument.