Superstorm Sandy inundated Lower Manhattan, causing billions in property and infrastructure damage. To protect against future flooding, storm surges, and sea level rise, landscape architects are developing an innovative mix of green and grey solutions along the southern coast of Manhattan.
These are not nature-based solutions but forms of armor. And designers are showing how this armature can be woven into the public realm, creating new kinds of infrastructure. Smart design is resulting in retractable gates and walls, landscaped berms, and raised platforms. No concrete walls separating communities from each other or the waterfront here.
The concept behind this effort is called the Big U and it came out of the Rebuild by Design competition funded by the U.S. Department of Housing and Urban Development (HUD) in the aftermath of Sandy. Since then, billions in federal, state, and city funds have gone to making the plan a reality.
Related Article
How Can Architecture Combat Flooding? 9 Practical Solutions
The plan is being designed and implemented through the Lower Manhattan Coastal Resilience Program. This effort spans many jurisdictions and includes lots of sub-projects, explained Gonzalo Cruz, ASLA, vice president of landscape and urban design at AECOM, during an event organized at the offices of SCAPE as part of Climate Week NYC.
AECOM has developed the master plan for the projects. "There are twelve teams on board, with lots of public sector leader and community participation — many invested parties at the table," Cruz said.
All teams are united behind the goal of creating new infrastructure that reduces flood risk but also creates places people want to be in.
Under FDR Drive on the east side of Lower Manhattan near the Brooklyn Bridge, AECOM is adapting the design standards for the former East River Esplanade Masterplan designed by Ken Smith Workshop and Shopp Architects.
A series of retractable gates are being woven into the park along the East River. "They are like transformers; think of them as a mechanically operated landscape," Cruz said. "During major storm surges, they will operate and flip up."
The gates enable the landscape architects to keep the waterfront as open and accessible as possible during good weather.
Further north on the east side, landscape architects with MNLA are bolstering 2.4 miles of riverfront from Montgomery Street to 25th Street. Nearby communities are in the floodplain. During Sandy, many of the housing developments were hit hard and isolated by rising waters, so the plan also addresses their risks.
The East Side Coastal Resilience Program reimagines a necklace of neighborhood parks, incorporating new coastal defenses. How the defenses are integrated also changes along the length of the riverfront.
The new riverfront parks will be eight feet above the river and essentially built on top of the existing parks. "The new parks include flood protection elements, and portions of the East River Park are elevated to connect to new pedestrian bridges," said Molly Bourne, FASLA, a principal at MNLA.
To improve the resilience of the landscapes, MNLA added in a diverse range of soil mixes, trees, and plants that can handle "wind, waves, inundation, and salt."
A narrower segment of the linear park includes a defensive berm with that resilient soil, tree, and plant system. But it still provides ample space for bike lanes and pedestrians.
A new pedestrian bridge high over FDR Drive will improve access to the waterfront while ensuring the community will not be isolated in the next superstorm.
The Big U continues around to the west side of Lower Manhattan. There, landscape architects at SCAPE and BIG have been designing the Battery Park City Resilience Projects.
In seven projects, "we are using berms, platforms, hills, and retractable gates to create a line to stop the water," said Greta Ruedisueli, ASLA, an associate with SCAPE. They are all "strategically placed" to blend into the communities.
In some neighborhoods, existing waterfront platforms are being raised and rewoven into the community.
And in others, subtle grade changes and berms help maintain the line of defense, while flood walls built into constructed hills ensure no river surge will seep underground into the community.
The grade changes and land forms enable SCAPE and BIG/CSM to increase biodiversity through native trees and plants and provide spaces for residents and visitors to sit and take in the nature.
In Rockefeller Park, an artful flood wall is being stitched into a housing development. "The wall is a textural element. It can be concealed when it is high through material, color, and hue," said Rachel Claire Wilkins, Affil. ASLA, a senior landscape designer with BIG/CSM.
All this new infrastructure is being designed for the future. "We expect flooding to be higher in 25-50 years," Wilkins said.
It is also being designed to flood and then bounce back from inundation. "Occasional flooding will be OK," Bourne said. "What is important is that the landscapes remain usable up to the water's edge." To ensure that, all the infrastructure below ground and plants and soils are being designed to adapt to inundation.
Bourne thinks these projects are "precedent-setting" because they haven't been done before in a dense area like Lower Manhattan. "We are in new territory. But we have designed this infrastructure to be easier to maintain in the future."
Cruz said other landscape architects working on coastal flood defenses need to understand how the engineering works before bringing design ideas to the table.
"You will be crushed if you don't understand the mechanisms. We can't be too tree hugger-y. These systems have to perform. It's about how to make them last the longest and provide the most benefit to the most number of people."
This article was originally published on The Dirt.
