Rising Risks

With Coastal Cities under Constant Threat of Flooding, Urban Development Leaders Prioritize Resiliency Projects




Long Island, New York, USA

By 2050, at least 570 cities and some 800 million people will be exposed to rising seas and storm surges.

Source: World Economic Forum

For as long as humans have been building cities, they have migrated toward the coasts—for food, ease of transportation and any number of ecological benefits. Today, it’s estimated that more than 2 billion people live within 60 miles (100 kilometers) of a coast, according to the United Nations. And some of the largest cities in the world are coastal, including Tokyo, Japan; Mumbai, India; Lagos, Nigeria; and New York, New York, USA.

Yet that preference is now putting many in the path of peril. Rising sea levels are wreaking havoc, displacing thousands of residents and generating economic losses in billions of U.S. dollars, according to the World Economic Forum’s Global Risks Report 2020. By 2050, it’s estimated that at least 570 cities and some 800 million people will be exposed to rising seas and storm surges. And an October study published in Nature Communications estimates that unstable Antarctic sea levels this century could flood coastal areas that are home to as many as 480 million people.

Although urban development is adapting in myriad ways, what stands out is an embrace of resiliency—that is, designing and executing projects so that these public spaces can withstand floods and storms when, not if, they happen. The resiliency focus, which still prioritizes both the aesthetics and the end user’s experience of a space, is on full display in waterfront park projects. These public developments buffer the city from the sea and often serve as one of the few spaces in which urbanites can find respite in a sliver of nature.

“If you work innovatively with resilient strategies, you can actually create multiple benefits: a more livable city, new social and urban destinations, multifunctional spaces, improved access to and understanding of nature, and a vital understanding of the challenges we are facing,” says Lasse Vilstrup Palm, associate partner, head of landscape and urbanism, C.F. Møller Architects, Aarhus, Denmark.

Mr. Palm’s firm is behind the Stork Meadow project in Randers, Denmark, which is slated for completion in 2021. Randers’ low elevation leaves it vulnerable to flooding, a threat that’s been exacerbated in recent years by heavier rains and more frequent flooding of the Gudena River. The city launched a design competition for a project that could balance requirements on three fronts: urban planning to satisfy the city’s expansion needs, climate-change adaptation to help mitigate the impact of flooding and nature conservation to stabilize the local ecosystem.

The Stork Meadow team is threading elements of resiliency throughout the project’s design. “Cloudburst routes” will send rainwater runoff from roofs, car parks and roads into purification basins in the park’s water meadows before flowing it back into the Gudena River. Park roads previously built with nonporous surfaces, which blocked natural drainage, have been redesigned to prevent water buildup. And throughout, the team prioritized how people would use the space: A new dike between the nature park and the river is topped with nature paths, a raised boardwalk stretches from the town throughout the new water meadows, and a suspended rope net invites people to sit above the water basin and take in the views.

Approaching the waterfront park design through the lens of climate adaptation increased complexity—and potential rewards, Mr. Palm says. “We believe you get the biggest benefits in areas where you find the largest economic values as well as the largest risk for loss of infrastructural, urban, technical and social values,” he says. “Within this complex urban context, you can get multiple benefits out of one project investment.”


—Lasse Vilstrup Palm, C.F. Møller Architects, Aarhus, Denmark



At left and here, Stork Meadow project in Randers, Denmark


In November, the government in New York, New York, USA approved plans for the US$1.45 billion East Side Coastal Resiliency (ESCR) project. The massive initiative will mitigate the threat of future floods by using landfill to raise East River Park to 8 to 10 feet (2.4 to 3 meters) above sea level, along a 2.4-mile (3.8-kilometer) waterfront stretch. Plans also call for a system of barriers to be built.

Planning dates to Hurricane Sandy, which ravaged the city in 2012 and is one of the costliest storms to hit the United States, causing an estimated US$70 billion in damage. Originally envisioned as one massive project and dubbed the BIG U Rebuild by Design, the initiative became one of two separate projects, along with the Lower Manhattan Coastal Resiliency Project.

“There’s a lot of stakeholders and interests that you have to negotiate” on public waterfront projects, says Simon David, the project’s leader from 2015-2018 and currently founding principal of design and resiliency firm OSD Outside, New York, New York. “In my mind, that’s the biggest defining feature of coastal resiliency projects.”


–Simon David, OSD Outside, New York, New York, USA


For the ESCR team, nailing down plans and securing buy-in required coordinating with the mayor’s office, as well as stakeholders at the city’s departments for parks, transportation, design and construction, city planning and environmental protection. Each of those agencies had its own protocols for communication and status updates—something that was imperative to accommodate to keep momentum during the planning and approvals process, Mr. David says. “You’re tailor-making this vision for the city, but that can feel a bit like taking this vision and cranking it through the ‘New York City Agency Machine’ so it comes out in familiar forms.”

Bureaucracy doesn’t only lengthen timelines—it can also reshape project scope. “Regulations are not always in alignment with what you want to accomplish,” says Edgar Westerhof, who worked on the ESCR project and is the U.S. national director for flood risk and resilience at the U.S. office of Dutch design firm Arcadis. “The best solution might not always be the feasible solution due to regulations.”


—Edgar Westerhof, Arcadis, New York, New York, USA

Project leaders also will have to win over residents wary of such megaprojects. Government meetings to discuss the ESCR were often packed with residents eager to speak out against the plan—some of whom started the East River Park Action group to organize opposition. And an October review by the U.S. branch of the global water research institute Deltares criticized the lack of publicly available information on certain aspects of the project. The report argued that “transparency of the decisionmaking process by city agencies will help rebuild trust and gain support of the community” and recommended the city establish a community advisory group to better involve residents in the project’s final design and planning.

Stakeholder buy-in is the beating heart of many such project plans. In Hoboken, New Jersey, USA, prioritizing public support has been at the core of a project to rebuild and reinforce the city’s post-Hurricane Sandy infrastructure, says Daniel Pittman, a former project manager on the Resist, Delay, Store, Discharge initiative.

“The duration of a waterfront project is likely going to outlive the political life of the mayor who approves it,” says Mr. Pittman, who is now a partner at TAD, New York, New York. “Having support across a broad section of the community will ensure that political will is maintained during the course of the project.”


—Daniel Pittman, TAD, New York, New York, USA



A rendering of the East Side Coastal Resiliency Project in New York, New York, USA. At right, two views of the Resist, Delay, Store, Discharge project in Hoboken, New Jersey, USA

Project leaders must find a way to toggle between highly technical project details and providing public access to information that’s easy to understand. To find that balance, “our presentations were very graphic heavy, very approachable,” he says. “We focused on presenting the big ideas and their impact. It’s much closer to PowerPoint than it is to a scientific thesis.”

The Resist, Delay, Store, Discharge project aims to bolster the city’s resiliency by weaving together hard infrastructure (such as levees) with soft infrastructure (such as parks). The plan includes flood walls capable of protecting high-risk sites along the riverfront; a network of parks and wetlands intended to act like sponges and help keep sewers and drains from overflowing; and a system of underground cisterns and retention basins, as well as pumps to hold and then discharge floodwater back into the river.

During educational events that the community was invited to, Mr. Pittman leaned into analogies. For example, he related the concept of a 1-in-100-year storm to the probability of certain card games. And at the end of each session, residents were given leaflets (complete with a glossary of terms) to review the project in greater detail on their own.


Though project managers can always glean lessons learned from similar projects, when it comes to technical designs and engineering details, there’s no question that each project plan must be tailored to its local environment, says Marten Hillen, water lead on the Resist, Delay, Store, Discharge project and regional director for engineering consultancy Royal HaskoningDHV, Stillwater, Oklahoma, USA. Mr. Hillen has worked on resilient urban development projects around the world, including in Singapore, the Netherlands and the United States. He says project managers must take the time to understand the community’s perspective—as well as its history with resiliency and urban development.


In the Netherlands, for instance, these projects have a longer track record of realized benefits, Mr. Hillen says, and residents are well aware of their proposed merits.

Singapore has recently placed a premium on safety in the face of rising sea levels, leading to strict requirements for its waterfront projects.

One such project is the development of a polder (low-lying land reclaimed from the sea) at the northwest tip of Pulau Tekong, an island just northeast of mainland Singapore. Mr. Hillen served as technical manager on the project, which was launched in 2008 and is slated for completion in 2022. Rather than use the traditional method of infilling with sand, the team opted to create a dike and network of drains, water pumps and canals. Once complete, the project will add roughly 810 hectares (2,001 acres) to Singapore, with a plan that’s designed to lower construction costs and increase resiliency against future flooding. It’s the first time the method will be deployed in Singapore.

“The project sponsors wanted a very small probability of failure and a very high safety standard, which is great,” says Mr. Hillen. “But it also has implications across the project plan. You have to design everything—up to the grass and the different layers of soil under the grass—with flood safety in mind.”

In San Francisco, California, USA, it’s mud that’s top of mind for teams tasked with making the city more resilient against rising tides and the threat of earthquake-related flooding. The 100-year-old Embarcadero Seawall stretches for 3 miles (4.8 kilometers) along the city’s waterfront and is in desperate need of an overhaul. So the city launched a US$5 billion, 30-year program to bolster waterfront resiliency. Construction is slated to begin in 2023.

One challenge: “We have soft soils on the San Francisco waterfront, called bay mud,” says Steven Reel, project manager, Port of San Francisco. “Where deposits are deep, it makes for very poor foundations. Raising the land even small amounts causes settlement.”

The original Embarcadero Seawall was built by digging a trench in the bay mud, some 100 feet (30 meters) wide and 30 feet (9 meters) deep, then filling it with rocks. A concrete wall was constructed on top, along with wooden pilings to construct piers. But new methods and technologies are needed to mitigate the risks of more powerful and frequent floods. San Francisco Bay has risen roughly 8 inches (20 centimeters) since 1900, and scientists predict it could rise up to 7 feet (2.1 meters) by 2100, according to a 2019 report published by California’s Legislative Analyst’s Office. In the long run, investing in the R&D to find innovative solutions has the greater potential to prevent costly damage, Mr. Reel says.



Embarcadero area in San Francisco, California, USA

“We’re now exploring adaptable wharves and floating wharves,” he says. “It doesn’t cost much more to just build new wharves to higher elevations, but making them incrementally adaptable over time requires new and innovative detailing that doesn’t exist yet, increasing design and construction costs.”


When projects are intended to deliver benefits that last for decades—and to protect thousands of people—budgets must be viewed with a wide and long lens, says Mr. David.

“I think it’s totally worth it to invest what you need to protect communities,” he says, while also stressing that resilient waterfront projects can, and should, be “more than just an engineering job.”

On the technical front, the ESCR project will elevate an existing waterfront park to protect residents against floods and rising sea levels. But the existing park will also be transformed into a community-based space that more naturally fits into its surroundings and encourages residents to gather and linger.

“By doing that, you’re creating richer community interaction on a day-to-day basis, which creates a stronger sense of connection to one another and to the place,” Mr. David says. And fostering those interdependent relationships can also be a crucial component of city resiliency, he says, because when a crisis hits, people will be more inclined to look out for each other.

“When public space is designed the right way, it should make you feel that other people are critical to your survival, not a threat to your survival,” Mr. David says. “Because of that, people spend more time around each other. They spend more time investing in the world around them, in their immediate physical environment. They participate more in the conversation about how we look after it.” PM



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