Case Study: New York City and Sea Level Rise Adaptation Planning
New York City has a high level of exposure to sea level rise due to its coastal location on the Hudson estuary and its barrier shoreline on the Atlantic Ocean, but its status as the most densely populated city in the U.S. makes it particularly vulnerable in comparison to other coastal cities with similar geographies. Hurricane Sandy shut down New York, cut power for days or weeks to hundreds of thousands of people, flooded homes and businesses in Manhattan, Staten Island, Queens, and many other areas, and caused $19 billion in damages and economic losses and at least 44 deaths of city residents. The New York Stock Exchange closed for two days, sending economic shockwaves worldwide. The Subway and all of the road tunnels connecting Manhattan island to the mainland were flooded and disabled. One thing Sandy also achieved was to focus public attention on the vulnerability to storm surges and sea level rise of the economic center of the U.S. In the years since Hurricane Sandy in 2012, a great deal of work has been done to address New York’s vulnerability to flooding from storm surge and sea level rise. There have been multiple proposals, plans, and strategies considered for increasing New York’s climate change resilience through adaptation.
Some of the major concerns that are being addressed in the planning process are:
- As sea levels rise the number of people living within 100-year (1% annual chance of flooding) flood zone areas will increase significantly. The number is estimated at 20 million by 2050. This will necessitate many more property buyouts such as those that took place after Hurricane Sandy.
- Water treatment plants (an estimated 40%) will be compromised by flooding, increasing the risk of contamination.
- Power plants (an estimated 60%) will need to be relocated, flood proofed, or elevated to avoid flooding, which would threaten the city’s power supply, especially during high water times.
- Transportation systems will need to be upgraded to avoid regular flooding. This includes highways, airports, bridges, tunnels, subways, and railroads.
Other areas of essential infrastructures, such as the Meadowlands in New Jersey, will flood. This area of warehouses, railroad yards, and other important commercial infrastructure is slated for conversion to a national park in the future.
Plans for addressing the increasing threats of flooding include:
- Designs for large barrier systems to protect the city by blocking the storm surges and from the Atlantic Ocean from entering New York Harbor;
- Designs for rethinking the land use of Manhattan and surrounding boroughs, returning some areas to green space.
- Increased number of property buyout projects. During the recovery period following Sandy New York state encouraged homeowners who qualified to participate in a property buy-out program, an example of managed retreat, as described in Module 9. Hundreds of homeowners, including those in Staten Island communities, chose to do so and move to safer locations and the neighborhoods where their houses once stood have been returned to nature, providing tidal flooding buffer zones.
Visit New York’s Fourth Regional Plan to read more details about how this planning process is playing out. This page addresses protecting coastal communities from storms and flooding. An important aspect included in the page linked here is ensuring that the planning process is equitable for all members of the communities it affects. The physical exposure and social exposure maps illustrate where socially at-risk communities are located in relation to the physical exposure to flooding. This consideration was discussed in Module 11 and will also be the focus of Module 13 lab. So where does New York City stand in terms of sea level rise adaptation policy after years of planning? All of the plans are at some stage in the process of becoming reality, but in many cases, they have not yet moved into implementation as the projects involve years of design and community input and are extremely expensive so full funding is hard to achieve. As outlined in the MIT Technology Review article The "mind-boggling" task of protecting New York City from rising seas, although New York is ahead of most coastal cities in climate change adaptation planning, none of the big ideas that were funded by the federal government as a result of the Rebuild by Design competition for Manhattan have actually begun construction, but we will see construction soon.
For residents of Manhattan, the focus has been on the plans to create a 10-mile perimeter of multi-use waterfront space around Lower Manhattan that includes a combination of flood protection and green space that can absorb flood waters when inundation occurs. This project began with the Rebuild by Design Competition where design companies were invited to submit proposals for flood resiliency plans for lower Manhattan. Proposals were chosen and teams formed to create the designs. The design firm Bjarke Ingels won the contract to develop the design and the proposed project became known as the “Big U”. Years of planning, design work, and community stakeholder input through facilitated workshops took place and the completed plan was presented to the city. As the video linked below outlines the city is now beginning the implementation of the plan, but with major changes, with which some of those involved in the complex planning process are not entirely happy. The video explains the steps and shows maps of the designs, which include a fringe green space around the lower part of the city, with elevated berms to hold back the water as well as lower elevations designed to flood at times of high water. Stakeholder input ensured that the needs of all sectors of the community were met. An emphasis was placed on public access so that the whole project provided recreational opportunities for city residents and visitors.
Video: The Big U | Going In With Brian Vines (9:52)
The video provides a good example of how adaptation planning with stakeholder participation works. The New York City government made some executive decisions after the planning process was completed that changed the plans significantly. The changes removed some of the components involving allowing flooding of park areas in times of high water, preferring elevated berms over intentional lower elevations and natural habitats. It will be interesting to see how the plans are finally implemented, how the public feels about the results, and how the project as a whole and its component parts perform when high water affects lower Manhattan, as a result of a storm surge or the inevitable higher tides in the upcoming years.