Retreat

As I have shown in my earlier science posts, sea level rise is one of the biggest challenges New York City will face due to climate change. The storm surge of Hurricane Sandy made it clear that the city was not equipped against floods caused by extreme weather events. In earlier posts two options were explained, a “soft” approach – beach nourishment – and a “hard” approach – barriers. In this post we will discuss retreat, the option left when nothing else will work.

Retreat is the act of moving away from the shoreline. Residents are encouraged to sell their land and then the government allows the land to return to its natural state. The option was discussed in Gornitz et al.’s 2002 paper Impacts of Climate Change on NYC Coasts. In Storm Surge, Sobel mentions a similar plan in the Netherlands. “Return to the River” forced residents, who were mostly farmers, to leave an area, which was then returned to a floodplain. A few negotiated to stay in the area, but the majority left.

After Hurricane Sandy, it became even clearer that retreat would be necessary. While Bloomberg said that retreat was not an option (Revkin 2013), Governor Cuomo signed off on the purchase of three neighborhoods in Staten Island, Oakwood Beach, Ocean Breeze, and Graham Beach, for retreat as part of the Hazard Mitigation Grant Program. These neighborhoods had almost all of the residents agreeing to sell their homes, with a few holdouts (Rush 2015a). During his State of the State address, Cuomo said, “There are some parcels that Mother Nature owns […] She may only visit once every few years, but she owns the parcel and when she comes to visit, she visits” (Homeland Security News Wire 2013). Many other neighborhoods along the east coast of the island, all of which were hit very hard by the storm surge of Hurricane Sandy, wanted to get in on the buyout, but a representative of Cuomo said the governor would not authorize the purchase of the entirety of the coast. The purchased neighborhoods have already begun to be demolished and reestablished as wetlands. The land would be planted with native grasses and retention pools would be built to capture the rainwater. The process cannot be completed until all residents leave. A large section of one neighborhood is currently owned by a developer who is holding out on selling the land, which poses a problem for the reestablishment (Rush 2015b).

A home in Oakwood Beach waiting to be demolished – Source Urban Omnibus

There are other options for homeowners who want to relocate. “Build It Back” is a program which offers to pay for repairs or elevation of homes hurt by Hurricane Sandy. An acquisition program run alongside “Build It Back” offers to purchase homes on their own instead of a neighborhood buyout. The difference between this type of purchase and a group buyout is that individual purchases do not get returned to nature, instead they are redeveloped and new structures are built. This is not as good of a plan as retreat. Most of the areas that become severely flooded during storms used to be wetlands and were backfilled to make room for buildings. More than half the people who died during Hurricane Sandy lived in areas that used to be wetlands (Rush 2015a). Rebuilding on these areas could increase the number of fatalities in the future.

Retreat, though the severest choice in the fight for the coast, is the safest option both for human life and wildlife. Beach nourishment and barriers both lead to erosion and damage the habitat of wildlife that lives in the area. They are also incredibly costly and though barriers can reduce flood levels, they still leave residents in danger from the water that makes it over the seawall. Retreat puts no one in danger and returns the land to its natural state. Wetlands will protect the coast from sea level rise and storm surges. They will serve as a buffer for nearby residents from the elements and also vice versa by stopping runoff from going directly into the ocean.

In the next, and final, science blog we will take a look at some of the invasive species I got to know during my visits to New York parks.

 

 

Bibliography:

Gornitz, V., S. Couch, and E. K. Hartig. 2002. Impact of sea level rise in the New York City metropolitan area. Global and Planetary Changes 32: 61-88.

Homeland Security News Wire. 2013. NY to buy, demolish beachfront homes, make way for storm buffers. Homeland Security News Wire. http://www.homelandsecuritynewswire.com/dr20130207-ny-to-buy-demolish-beachfront-homes-make-way-for-storm-buffers

Revkin, A. C. 2013. Can Cities Adjust to a Retreating Coastline. The New York Times. http://dotearth.blogs.nytimes.com/2013/08/22/can-cities-adjust-to-a-retreating-coastline/?_r=0

Rush, E. 2015a. As the Seas Rise: Managing retreat along New York City’s Coasts. New Republic. https://newrepublic.com/article/123182/managing-retreat-along-new-york-citys-coasts

Rush, E. 2015b. Leaving the Sea: Staten Islanders Experiment with Managed Retreat. The Architectural League’s Urban Omnibus The Culture of Citymaking. http://urbanomnibus.net/2015/02/leaving-the-sea-staten-islanders-experiment-with-managed-retreat/

Sobel, A. 2014. Storm Surge: Hurricane Sandy, Our Changing Climate, and Extreme Weather of the Past and Future. HarperCollins. New York, New York, USA.

Vinnitskaya, I. 2013. NY State’s Governor Cuomo’s Solution for Ravaged Homes in NYC’s Coastal Region. Arch Daily. http://www.archdaily.com/331154/governor-cuomos-solution-for-ravaged-homes-in-nycs-coastal-region/

Image: http://urbanomnibus.net/redux/wp-content/uploads/2015/02/FoxBeach011_resize-650×465.jpg

 

 

Barriers

With the threat of rising sea levels, the New York City government has to seriously consider how to protect its land. New York is not only threatened by elevation of the water level, which could decrease the size of coastal areas, but also by the increasing damage that could be caused by storm surges. One way that the coast could be protected is by building barriers.

Examples of barriers include seawalls, groins, and jetties. Seawalls are exactly what they sound like, walls built in the sea, which protect the coast from being inundated with too much water (Gornitz et al. 2002). Groins are a series of posts or sometimes a wall, built onto a beach that is meant to catch littoral sand that is moved by the currents. Jetties are long strips of land that make inlets stable and protect harbors from the worst effects of waves. The decision of where to place barriers and what kind of barrier to use is vitally important, both to the area it protects and the ecosystem it affects.

After the disastrous effects of Hurricane Sandy, New York City had to consider what can be done to protect itself. One option that was first thought of was to build moveable barriers in the ocean, like those found in the Netherlands. (Sobel 2014) There are examples of barriers like that as close as New England, protecting small channels from being flooded with water. But those types of barriers only work for small areas. The shores of New York are too long to be protected by a moveable barrier. Bryan Walsh wrote in Time that a Dutch-style barrier surrounding New York City from Sandy Hook, New Jersey to Rockaway Beach would be an option, but would cost anywhere around $10 – $15 million (Walsh 2012). Christa Marshall in Scientific American wrote about a proposal to build two different seawalls, first a seawall in the East River, then a seawall from Sandy Hook to Rockaway Beach (Marshall 2014). This double seawall would create an extra layer of protection. It is doubtful that this will completely stop all flooding, but it would limit the amount of damages that would occur in New York. Still, though barriers are able to stop water from damaging the land, they also have great consequences.

A rendering of a sea wall between Brooklyn and Staten Island – Source Fox News

The greatest consequence of coastal barriers is erosion. With seawalls, erosion occurs both at the base of the seawall (Gornitz et al. 2002) and further down the coast where the seawall does not extend. These areas suffer even more than they usually would because the seawalls just move the waves further along and when they reach an unprotected area, the waves are even more powerful than normal (Dunn 2009). If rubble is placed directly next to the seawall, erosion at the base can be decreased. Groins, if they are not placed in the right spot usually increase erosion of beaches further downstream, as do jetties. Erosion of beaches causes habitat loss for animals who nest or lay eggs there and can decrease the number of invertebrate species who live on the beach (Dugan and Hubbard 2010).

New York must consider the cost of building barriers. Though they might protect the city from flooding, they could also pass the consequences further along to other cities. Building barriers is considered to be a “hard” approach. In the next science post, I will investigate a “soft” approach, beach nourishment.

 

 

Bibliography:

Dugan, J.E., and D. M. Hubbard. 2010. Ecological Effects of Coastal Armoring: A Summary of Recent Results for Exposed Sandy Beaches in Southern California. US Geological Survey, Department of Interior. Scientific investigations report, 2010-5254. Reston, VA, USA.

 

Dunn, P. 2009. Can Seawalls Prevent Beaches from Eroding?. MIT School of Engineering. http://engineering.mit.edu/ask/can-seawalls-prevent-beaches-eroding

Gornitz, V., S. Couch, and E. K. Hartig. 2002. Impact of sea level rise in the New York City metropolitan area. Global and Planetary Changes 32: 61-88.

Marshall, C. 2014. Massive Seawall May Be Needed to Keep New York City Dry. Scientific American. http://www.scientificamerican.com/article/massive-seawall-may-be-needed-to-keep-new-york-city-dry/

Sobel, A. 2014. Storm Surge: Hurricane Sandy, Our Changing Climate, and Extreme Weather of the Past and Future. HarperCollins. New York, New York, USA.

Walsh, B. 2012. Sandy: What a Coastal U.S. Can Learn from Other Threatened Cities. Time. http://science.time.com/2012/11/05/sandy-what-a-coastal-u-s-can-learn-from-other-threatened-cities/

Image – http://www.foxnews.com/science/2013/10/29/one-year-after-sandy-progress-on-20-billion-sea-wall.html