Three ways American cities can become more flood-resilient and beautiful » Yale Climate Connections

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From shiny metallic blue amphitheaters that serve as floodwater storage pools, basketball courts, and skateboarding rinks to double-decker road tunnels that can fill with stormwater and still remain usable for travel, cities around the world feature creatively designed multipurpose facilities that can both protect communities from weather disasters and bring people together in public spaces with nature.

As storms and floods become more frequent, intense, and expensive in terms of finances and lost lives, city life is becoming more precarious.

Amit Prothi, the director of the Coalition for Disaster Resilient Infrastructure, has spent decades working on making communities more resilient across more than 15 countries in North America, Asia, and Europe. He said that American infrastructure – like power lines, water drainage systems, and housing development – and building policies that govern such projects may not account for the changing risks brought about by climate change.

A 2021 report by First Street Foundation, a science and technology nonprofit, estimated that 25% of the critical infrastructure in the U.S., like airports, residential properties, streets, and emergency services like hospitals, police, and fire stations, are at risk of becoming inoperable in today’s climate in cases of flood emergencies alone.

But there are several strategies U.S. cities can put in place to become more resilient. As a bonus, implementing these strategies can also make cities more beautiful and community-oriented – and in most cases, are also financial no-brainers.

1. Invest in trees and green spaces

Photo of a sidewalk lined by regular trees and green grass
Benjamin Franklin Parkway, Philadelphia (Image credit: Philippe Gerber/Getty Images)

More frequent and devastating floods pose big risks to U.S. cities, with flood-prone areas expected to grow by nearly half in just this century. Some cities, like Philadelphia, have taken the lead in designing policies to ensure their infrastructure can withstand them.

In 2009, Philadelphia launched a GreenPlan, with goals to add green spaces like trees, open spaces, trails, and green schoolyards and streets that can soak up stormwater naturally. Green spaces “function as retention areas for water that don’t need a lot of hard drainage,” Prothi explained.

In 2023, city officials released a strategic plan for an urban forest, a road map of dozens of recommendations for tree planting with a goal to provide 30% of tree coverage to each neighborhood within 30 years. In addition to reducing floods, trees offer protection against rising temperatures, as areas under trees can be significantly cooler in hot weather. In many American cities, including Philadelphia, tree coverage is unequal and typically more sparse in neighborhoods with lower incomes and communities of color.

Another approach that could be more widely deployed includes regulations that govern the rate of runoff water in places newly converted from vegetated areas – which naturally absorb water – to hard surfaces like roads and concrete.

Prince George’s County in Maryland revised its building permits in 2007 to require new developments to maintain “as nearly as possible, the predevelopment runoff conditions” of water drainage, Prothi said.

2. Prevent new construction in risky places

Photo of a road covered by water Photo of a road covered by water
Flooding in downtown Annapolis, Maryland, as Hurricane Jose churned off the coast in 2017. (Photo credit: Flickr user alliecat1881 / CC BY-NC 2.0)

When the goal is to reduce the risk of flooding, one of the “most effective things we can do is put something in a safer place rather than a less safe place,” said Jack Baker, a professor of civil and environmental engineering at the Stanford Doerr School of Sustainability.

Regulations on where and how to build development can reduce property risks and disruptions to entire communities. And they can prevent flooded-out buildings from becoming eyesores.

Adding protections – like raising or relocating structures – after the fact gets expensive, Baker explained: “Policies around where we put things are super important and have a lot to do with keeping people and keeping assets out of harm’s way.”

3. Employ nature-based and multipurpose facilities

Photo of a concrete plaza with seats. The lowest area of the plaza is filled with water. Photo of a concrete plaza with seats. The lowest area of the plaza is filled with water.
The Water Square in Rotterdam. (Photo credit: Flickr user stadtlandschaft / CC BY-NC 2.0)

Cities across Europe and Asia have leaned into creative multipurpose spaces that tackle a need for more community spaces and disaster protection.

The Netherlands city of Rotterdam’s Water Square, a once-empty and monotonous square, has been revitalized as three large rainwater collection ponds. During the city’s heaviest rainfalls, the largest and deepest pond in the center of the square turns into a spectacular water wall on one of its four sides. The collection pools have shiny metallic surfaces painted in different shades of blue and were deliberately constructed as wide surfaces so that when the weather is dry, the pools are used as basketball, football, and volleyball courts and skateboarding rinks. The square is complete with elevated, tiered rows of seating.

Similarly, Stormwater Management and Road Tunnels, or SMART tunnels, have been built in Malaysia’s capital Kuala Lumpur – a project meant to alleviate flash flooding. Prothi explained that the double-decker tunnels connect one neighborhood to another, so when there’s excessive rainfall, parts of the tunnel become a storage area for floodwater.

The tunnels looping through Malaysia’s capital are also painted vibrant shades of blue. The structure was named one of the greatest tunnels in the world for its ability to prevent billions of dollars of flood damage and costs from congested traffic.

Photo of a city tunnel entrancePhoto of a city tunnel entrance
A SMART tunnel in Kuala Lumpur. (Photo credit: Emran Kassim / CC BY-NC 2.0)

Another way to improve a city’s climate resiliency and beauty includes building more development, like public parks and local businesses, near subway lines and stations. Prothi said that adding more development around stations encourages people to use public transit rather than cars.

Arlington County in Northern Virginia has taken the lead on prioritizing development near metro stations as part of its efforts to create attractive communities with extensive options for housing and transportation near jobs, shops, and schools.

“It’s really fascinating to see aerial imagery of Arlington County,” Prothi said. “You’ll see that at each metro stop, you’ve got taller buildings and more development.”

In the U.S., the Lower Manhattan Coastal Resiliency project, backed by over $1.7 billion in capital investments protection by the city, state, and federal government, plans to extend the region’s shoreline by 200 feet to accommodate a multilevel waterfront that will provide flood protection and new open space. The upper level, according to the plan, “will be elevated to protect against severe storms like Sandy, while doubling as public open spaces with sweeping views of the city and harbor,” while also safeguarding the city from rising sea levels and coastal storms.

There are also several projects underway by the U.S. Army Corps of Engineers – including a $13 billion project in San Francisco that would elevate the city’s embarcadero and install flood barriers in other parts of the shore, and the Dallas Floodway Extension Project, a flood risk management project that reached a milestone construction goal in October 2023.

Going green saves money

Every $1 invested in resilient infrastructure yields a $4 return in avoided recovery costs, according to case studies published by the World Bank and the Coalition for Disaster Resilient Infrastructure. FEMA estimates those cost savings can be even higher in the U. S. – and suggests federally funded climate mitigation grants “can save the nation $6 in future disaster costs for every $1 spent on hazard mitigation.”

While the cost-savings are clear, Baker explained, “Many times it’s not sufficient to trigger action when it would be helpful.”

“Certainly we can calculate costs and tabulate potential future benefits, but the tangible effects of disasters are kind of invisible to us until they are experienced,” he said.

Another challenge is that the groups or entities that often pay for resilience infrastructure are not always the beneficiaries – for example, “real estate developers that are building things to sell off are not always the ones who are going to occupy the houses,” Baker said.

“We are at an unusual time in human history that we’ve created problems for ourselves, but we also have these amazing abilities to look into the future through analysis and not just rely on lived experience to make good decisions in the world,” he added.

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