An Evolving Coastal City

An Evolving Coastal City

Sandy Aftermath, Lower Manhattan. Photo source: ©© Gilad Lotan

By Marcha Johnson, November 12, 2012

In response to Superstorm Sandy, the NY Times and other news media are to be applauded for publishing a series of imaginative ideas for rethinking our relationship with the shore. Two of the most eye-catching images were a giant tide gate at the mouth of the harbor, and Manhattan surrounded by salt marsh. Oyster reefs were proposed as shoreline stabilization. A little closer look at these proposals reveals that none of them, exciting as their renderings might look, could have “saved the city” from Sandy, that is, the whole city.

Parts of Brooklyn, Queens and Staten Is, would have been outside the tidal surge protection, or subject to surge from other directions, along with Long Island and New Jersey. If the storm had brought torrential rain, as such weather systems often do, flooding in low areas would have been widespread anyway. Salt marshes exist up to the spring high tide line, about elevation 4 feet in our region; oyster reefs generally occur around mid-tide. Surrounding Manhattan with oyster reefs and/or marshes would not have prevented flooding by a storm surge of elevation 13 feet, regardless of other benefits to the environment.

The issue of communities with fixed urban structures in flood zones facing storms and/or rising sea level is larger than NYC; it is not new, unique nor insurmountable. Long-lived civilizations care for more than one city at a time, one issue at a time. New York City is part of an interconnected regional system of economies, transportation infrastructure and social fabric from Washington to Boston; the whole corridor faces the question of how to adapt, as does the rest of our East and West Coasts, and cities around the world.

Building housing and critical infrastructure at grade along waterways (ConEd facilities and FDR on the East River), dunes and barrier beaches (the Rockaways) and floodplains and wetlands (much of lower Manhattan) involved choices by governments, real estate developers, zoning planners and private and public buyers over a couple centuries. Sea level has been rising since the end of the last Ice Age around 10,000 years ago. As for the expensive infrastructure investment needing protection… most of it is quite recent, less than 100 years old. Rebuilding in different ways as technology and conditions change is a normal part of what cities do.

This is an excellent moment to reconsider the basis of former decisions… to come up with more highly evolved types of coastal cities, adaptable to changing conditions.”
—Marcha Johnson

This is an excellent moment to reconsider the basis of former decisions based on the best current information, to draw on the wisdom of other water-edge societies especially indigenous cultures, and engage the most creative, puzzle-solving contemporary minds which can be found, to come up with more highly evolved types of coastal cities, adaptable to changing conditions.

Speaking on last Sunday’s National Public Radio radio program, On Being, writer Joanna Macy described the present as, “The Great Turning,” a transition from a society shaped primarily by industrial growth to a society structured to be life-sustaining.

Here are three ideas for approaching a life-sustaining kind of society, one which adapts to changing conditions instead of rebuilding exactly in the place and in the way which made us vulnerable, trying to protect large areas with ever-higher walls.

Rolling easements
Rolling easements is a term for a combination of several approaches described in Orrin Pilkey and Rob Young’ The Rising Sea. Shorefront property owners are compensated while the inland migration of wetlands, beaches and estuaries is facilitated by gradually removing hard structures.

Some of what we think of as “land” would be better thought of as, “sometimes water.” Such places can be sold under different rules than those applied to upland, recognizing that they will be inundated occasionally. Naturalistic environments like beaches, dunes, marshes and riverbank plantings can much more easily survive hurricanes and flooding than rigid concrete and steel; they do this by moving around: new channels might form; dunes might disappear from one place and reform nearby; sand moves but the beach remains a beach; many floodplain plant species can regrow right where they fell over. Moving rigid infrastructure, even the Rockaway highrises, upland and inland would help protect it, letting natural systems operate in the most flood-prone areas.

Porous and flexible features
Integrating porous features in pavements and seawalls lets water move through the urban fabric, allowing helpful bacteria to remove some pollutants, creating healthier soil for supporting plants. Rough-textured underwater structures support marine organisms, many of which also filter water. Infrastructure which can float, flex or has inflatable/collapsible elements could temporarily adapt to changing water levels. NYC is already taking an admirable number of steps in this direction.

As if life depends on it Rebuild NYC, including the waterfront, as if life depends on it. NY Harbor is not only the place where oil tankers bring in gasoline. It is also an estuary, cleaner than it has been in a long while, but with much smaller populations of fish, shellfish and marine mammals than it once had. There used to be a strong fishing industry here. Loss of habitat is a key reason for the decline of life in the harbor. While rebuilding the water’s edge from Sandy’s impact, habitat in the estuary and the surrounding upland buffers can be strengthened and expanded.

Is there a single, spectacular solution, which will make us safe from future superstorms? Probably not. But there must be thousands of ways to make healthier, safer cities that work better. In being thoughtful about the next steps, choosing actions based on seven generations into the future as the Iroquois did, learning from what worked and failed during this and other big storms, there is every possibility that our civilization can continue thrive in this precious place which we know as home.

Now that Sandy has caught our collective attention with a real-life demonstration of NYC’s vulnerability and capacity for response and recovery, let’s teach ourselves many ways to live more wisely in a changing environment.

Marcha Johnson, PhD, is a Brooklyn landscape architect, ecological restorationist and adjunct professor, specialized in the ecology of urban waterfronts.

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