How Coastal Cities Are Evolving to Deal With Extreme Rain

Facing the specter of more and worse rainstorms, these vulnerable areas are turning to innovative urban design

Water water everywhere, and not a day to think. Geoff Marshall / Alamy

One afternoon this July, William "Skip" Stiles picked his daughter up from track practice as the rain fell with a ferocity that has become increasingly common in Norfolk, Virginia. The pair tried to return home through an intersection that was clear 15 minutes earlier, but it had flooded. Instead, they hung out at a sushi place until the waters died down. Later, Stiles learned that the storm had dropped a whopping 1.8 inches of rain in two hours. 

As flash storms increase in frequency and intensity, the aging infrastructure of American cities—especially older coastal cities like Norfolk—is proving unable to handle the extreme rains"Here and in most coastal cities there's no elevation. The water is not going anywhere," says Stiles, a former Congressional aide and executive director of Wetlands Watch, a grassroots activist organization that advocates for wetlands protection and climate change adaptation. "It just overpowers the infrastructure." 

While the focus is often on rain from hurricanes like Harvey, which last week dropped more than 50 inches of rain on portions of Texas, heavy rains from storms have increased throughout the country. Norfolk has seen an increase in one- and two-inch rain days since 1950, according to a recent rainfall study. In the Southeast, heavy rains are up 37 percent, while they have surged by 71 percent in the Northeast since mid-century, according to the 2014 National Climate AssessmentIn Charleston, these events are now so common that officials have given them a name: rain bombs.

In New Orleans, about 10 inches of rain fell in three hours earlier this summer, creating impassable streets and flooding homes and businesses. The city's pumping system, designed before World War I to handle an inch of rain the first hour and half an inch per hour after that, failed. A few days later, with more rain forecast, the mayor and governor declared a state of emergency. Schools closed. Residents were advised to park their cars on high ground.

The head of the city's Sewerage and Water Board, Joseph Becker, acknowledged that the city cannot handle heavy rains. “If you are asking me to drain 9 inches of rain, I need six times the pumping capacity, six times the drainage pumps and six times the canals,” he told City Council at the time. “I don’t need three or four more pumps, I need 400 or 500 more.” In recent years, Kansas City, New York, Los Angeles, Salt Lake City and Miami have also been flooded as their stormwater systems were overwhelmed by rains

The problem isn't just on the coasts. A recent study by the National Center for Atmospheric Research (NCAR) used a supercomputer to predict that the number of extreme storms across the country will increase over the century on the Atlantic and Gulf coasts, but also in portions of Arizona and Utah. "These extreme events are increasing very, very rapidly, especially in frequency and especially along the coastline," says Andreas Prein, a project scientist at NCAR and an author on the study. 

In some places, a city that in the past suffered one extreme storm dropping inches of rain in a few hours will see as many as five such storms in a summer, Prein says. Moreover, those storms will increase in intensity by 40 to 70 percent, meaning a storm that dropped 2 inches of rain in the past could drop 3.5 inches. "Losses are increasing rapidly due to these flooding events," says Prein. "I think more and more cities will start to prepare. The question is really whether you can prepare for this problem." 

Yet for many coastal cities, there isn't much of a choice.

Coastal cities like Norfolk and Charleston, where extreme rain forms a triple threat with sea level rise and subsidence, are in the vanguard seeking solutions to these extreme events. To do so, they're building improved stormwater systems and turning to nature for inspiration. 

While they may not sound as dramatic as hurricanes and earthquakes, the consequences of “rain bombs” are diverse and widespread. Kansas City, New York, Los Angeles, Salt Lake City and Miami are among the American cities that have been flooded as their stormwater systems were overwhelmed by rains in recent yearsAccording to the Insurance Information Institute, severe thunderstorms caused $14 billion in losses last year, about 60 percent of the total for natural disasters. (For comparison, hurricanes accounted for $3.5 billion in insured losses.) 

"To put this into perspective, a tropical cyclone is a very rare event, not every year is a tropical cyclone hitting Texas like Harvey," says Prein. "But if you live in the U.S., you will see thunderstorms this summer in most places. If you look at losses from tropical cyclones and from thunderstorms overall, they are in the (same) ballpark. The thunderstorms are not that expensive, but they occur much more frequently." From 1980 to 2013, flooding caused more than $260 billion in damage in the U.S., making it the costliest disaster threat in the nation. 

Health officials note that increased runoff also pollutes waters and creates exposure to toxins, increasing the risk for infectious disease and mosquito-borne illnesses. “Impacts include degraded storm water systems, infiltration into waste-water systems, contamination of fresh water supplies and salt-water flooding of roads, homes and businesses,” reads a 2015 report by the National Oceanic and Atmospheric Administration. “Tidal flooding is disrupting commerce and ways of life.”

In 2014, the Rockefeller Foundation funded a program to create 100 chief resilience officers worldwide to help cities identify environmental and economic challenges and build plans to address them. In Norfolk, a big chunk of that is dealing with the challenges posed by water, whether it's tidal flooding, subsidence, sea level rise or extreme rainfall. "In general, this really is about trying to figure out how you live with water, realizing the water is going to be taking up more space whether because of sea level rising or because it's raining harder or both of those things are happening at the same time," says Christine Morris, Norfolk's chief resilience officer.

Norfolk has a long-term resilience strategy that identifies areas vulnerable to rising waters and calls for using new technologies to reduce flood risk. It also uses a data analytics platform to evaluate the flood risk of every parcel in the city, something that drives zoning and building permits. Now, the city is considering applying a zoning overlay to the vulnerable areas that could require tighter standards for locating critical facilities like hospitals, schools and police in flood-prone areas, encourage the use of green infrastructure such as permeable pavers and establish flood buffers by preserving open space in high-hazard flooding areas.

Morris says the city is looking at a layered approach over time, scaling improvements as it determines what works and is needed. The idea is to think about ways to hold water, slow it, store it, release it and move it to acceptable places. The city relies on pumps to remove water from downtown, but she says it's looking at leveraging the natural hydrology. "We're flat so we have to think about how we use the landscape to move water to places where we can live with it more easily," she adds. "It's understanding: how did the water flow over this land? We've changed it. How do we use the old hydrology to help us in the future?"

Charleston is dealing with some of the same challenges as Norfolk, says Laura Cabiness, the long-time director of the city's Department of Public Service. "We have to look at those areas we're going to physically protect with engineering solutions," she says. "We have to look at land use planning to identify areas where water can encroach upon us without causing disruption ... It's not something we're going to solve within a year or two. It's long term."

In 2014, Stiles organized students from Old Dominion University in Norfolk and Hampton University in nearby Hampton to canvass the area and come up with innovative design ideasincluding cellar and underground cisterns, permeable pavers, rain gardens, upgraded storm drains and pipes and the reintroduction of planted wetlands along the riverfrontWhen they ran a computer model, the proposed changes reduced flooding from a famous 2009 nor'easter by 90 percent.

In 2016, Norfolk was awarded $120 million as part of a Department of Housing and Urban Development National Disaster Resilience Competition to turn those ideas into realities. The city is still in the design stages of work, focusing on solutions in Chesterfield Heights and Grandy Village, two neighborhoods dealing with frequent flooding. 

Morris says the city is exploring many of those ideas working with Arcadis, a Dutch-based firm that focuses on natural-based solutions and has completed projects in New York, New Orleans and San Francisco. Kyle Graham, the Arcadis program manager working with the city, says it's key that the solutions are able to be scaled-up if conditions change and they need to be replicable elsewhere. The city is gathering feedback from residents, and will begin work in March 2019.

Stiles says the key is having a long-range plan, as Norfolk does, and then searching for solutions by trying fixes in low-lying areas. "I think it is going to be a series of incremental, expensive steps to essentially buy us time to figure out what the solution is," he adds. "That's what Norfolk is doing. That's what Charleston is doing. That's what Miami is doing."

Right now, the price tag for implementing these strategies in the two neighborhoods is $155 million. But Morris takes the long view: History shows that as we get better at innovation, it gets less expensive, she notes. She adds that the region has the largest naval base in the world, the second busiest port on the East Coast, major shipbuilding industries and generates $94 billion of gross product annually. "We can't only talk about the cost," she says. "We have to talk about the benefits to the city and the region.”

Looking through that lens of resiliency is key, Morris says. "Every city evolves over time," she says. "Norfolk didn't look anything like this 50 years ago. It's not going to look anything like this in 50 years. So as we evolve, are we looking through that lens?"

Finally, it's important to realize that even if those solutions work, life in a coastal city like Norfolk will inevitably change. "There's going to be times when we have downpours where you're going to have water on the streets," Morris says. "With these big events, you're adapting to thembut you're not eliminating the inconvenience of them."

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