How do cities rebuild after hurricanes like Harvey and Irma?

The aftermath of a disaster is often focused on getting back to normal. But do cities need to think harder about how to withstand the next one?

Donald Trump visited a hurricane-stricken Houston and promised the “best ever” government response, before pumping his fist from the steps of Air Force One as he departed.

Greg Abbott, the Texas governor, marveled that the state’s “resilient spirit is alive and well”. The phrase “Houston Strong” has been daubed as graffiti on city underpasses and held aloft as placards at home baseball games.

There has been plenty of defiance, heart-rending loss, and uplifting generosity, in the wake of Hurricane Harvey, but one pressing topic has so far been largely overlooked: how will Houston rebuild in a better way should a storm like this ever again visit?

“When you talk about rebuilding a place like Houston, people’s first thoughts are “I want it back the way it was”, said Sandra Knight, a senior research engineer at the University of Maryland. “And unfortunately that’s not the best thing to do. As a nation we aren’t planning forward enough. We are developing in places that aren’t sustainable. We need to start doing things differently.”

Abbott has said a “Texas-sized storm needs a Texas-sized response”, predicting that reconstruction after the heaviest rainfall event in recorded US history – around 25tn gallons of water were dumped upon a band of southeast Texas in just a few days – will top the $120bn required by New Orleans after Hurricane Katrina in 2005.

It may well cost taxpayers in excess of $180bn. And it’s not yet clear what lessons will be learned.

Donald Trump visits with flood survivors of Hurricane Harvey in Houston.
Donald Trump visits with flood survivors of Hurricane Harvey in Houston. Photograph: Kevin Lamarque/Reuters

The US places huge emphasis on flood recovery, rather than avoidance, using the heft of Fema to help those in need as well as administer a national insurance scheme that ostensibly places restrictions on what is built where but in practice has repeatedly bailed out houses in flood-prone that are frequently inundated.

This emergency response is entirely appropriate in the immediate aftermath of a disaster, according to Jeff Herbert, chief resiliency officer for New Orleans. But, Herbert added, at some point a difficult conversation about whether a city needs to be refashioned as it recovers also needs to happen.

“Houston had 51in of rain and that would be disastrous for any city in the world, Mexico City, Bangkok, anywhere,” Herbert said. “It was unprecedented. The priority now is rescuing people and helping them.

“The next phase of recovery is the appropriate time to talk about how to rebuild the city. Houston will have to think about retrofitting to accept more water and think about its development patterns. The city will have to think about how it manages stormwater and its regulations.”

Houston has taken a rather laissez-faire approach to city planning, with a lack of zoning allowing housing to spill out over a large expanse, often in areas next to bayous vulnerable to flooding. The city is lacking in sponge-like parklands and is rich in concrete, which helps push water into unplanned streetscape swimming pools. The flat terrain of Houston, along with its proximity to the hurricane-spawning Gulf of Mexico, are further vulnerabilities.

Climate change is playing a role – the warming atmosphere holds more moisture that falls in the sort of rain that swamped Houston. The seas are rising faster on the eastern seaboard of the US than almost anywhere else in the world, heightening the impact of storm surges from hurricanes. Studies have shown hurricanes are likely to get stronger, if not more frequent, threatening coastal areas that are growing in population size.

This challenge, plus the pummeling experienced during storms such as Katrina and Sandy, which hit New York and New Jersey in 2012, has forced several cities to think about more natural defenses to water, rather than simply rely upon levees and pumps.

“In Houston and elsewhere we’ve encroached upon our floodplains and we aren’t leaving any natural environment to slow the flood waters,” said Knight. “We build dams and levees and people assume they are safe behind them, or downstream from them. But look at New Orleans – the levees failed.”

Knight said her initial training as a hydrological engineer focused on getting flood water off your land as quickly as possible. “But we’ve learned that’s not the best way to deal with floods,” she said. “We have a completely different landscape and climate now. They are complete game-changers.”

The Lower Ninth Ward in New Orleans, one of the areas worst hit by Hurricane Katrina, in 2015. New Orleans now has the largest flood barrier in the world.
The Lower Ninth Ward in New Orleans, one of the areas worst hit by Hurricane Katrina, in 2015. New Orleans now has the largest flood barrier in the world. Photograph: Carlos Barria/Reuters

In the 1950s, Dutch policymakers headed to New Orleans to learn how the city pumped excess water out into Lake Pontchartrain. A year after Katrina hit, the Netherlands returned the favour by briefing officials from the Louisiana metropolis about the Dutch mantra of “living with the water”.

This principle involves huge fortifications in key areas against flood waters – New Orleans now has the largest flood barrier in the world – but also emphasizes the need for green, or natural, infrastructure such as grass, woodland and wetlands to soak up water. Innovations such as green rooftops, where plants absorb some rainwater before it’s funneled to barrels rather than on to the street, and permeable pavements are also being embraced.

There are now seven “rain gardens” in New Orleans – essentially parks where water pools and is absorbed – and the city is spending a further $220m on new green areas that will draw away water that would otherwise end up in the streets or in people’s homes. Building codes have been tightened up to focus more heavily on flooding.

New Orleans is a different sort of city to Houston – it’s older and has less available land to be eyed by developers – but Herbert said its approach can be replicated.

“After Katrina we realized we had to live with water within the city,” he said. “We have hard infrastructure such as pumps but also nature-based solutions because pumping can’t handle it all. We had to go back to what existed in the city in the 1930s and 1940s, before mass development took place.”

The idea that water must be given space to flow in times of flood isn’t new; the Yolo Bypass was constructed in the 1930s to relieve Sacramento from the severe floods that plagued it. But many US cities are still developing close to low-lying coastal and riverine areas with barely a nod to what floodplains actually do.

Some have leaned heavily on technology – Miami Beach, which could soon be hit by Hurricane Irma, has spent hundreds of millions of dollars on raising its streets and developing a network of pumping stations. The low-lying city sits on a barrier island that already regularly floods on sunny days due to hide tides.

“Many cities have dams, levees and flood walls which are a fairly narrow and inflexible response to flooding,” said Jeff Opperman, global freshwater lead scientist at WWF. “There is growing appreciation in the US that we need to diversify, to set the levees back, use natural vegetation and allow the river room. But then there’s political decisions around development and that’s a less rational process.”

A 2015 study of six US cities found huge variations in response to extreme weather events fueled by climate change. While New York City and Los Angeles were deemed as making progress, Tampa in Florida, which may also suffer a brush with Irma, was found to be one of the least prepared cities in the nation, with its main hospital – situated on an isolated low-lying peninsula – demonstrative of the lack of preparedness.

“There’s a big variation in how cities are preparing, some are doing almost nothing,” said Sabrina McCormick, an academic at George Washington University and lead author of the research. “Houston’s approach to similar to other cities in that it hasn’t looked into the future and taken the risks seriously. Unfortunately we are seeing the ramifications of that.”

McCormick said a lack of federal leadership is also a problem. The Trump administration has struck down several Barack Obama-era regulations designed to reduce climate-driven risks. Ten days before Harvey struck Houston, Trump tore up a rule that demands federally-funded projects consider climate change and sea level rise before they are built.

“Ideally we’d have a national plan to help guide cities toward some basic level of planning to address these risks,” McCormick said. “If we don’t see that leadership, cities will have to look to other cities to figure out where to go next. We also need to mitigate our greenhouse gases to reduce the impact in the first place.”


Oliver Milman

The GuardianTramp

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