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Posts Tagged ‘flooding;climate change; sea level; Florida; limestone

Flooding in Florida: a preview of our future?

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Photo miami news times

Does anyone ever get used to living with repeated flooding?  As sea levels rise, this is a question that has become pressing.  Greater Vancouver is not immune; False Creek Flats, Crescent Beach, parts of Tsawwassen, to say nothing of Richmond and YVR, all these areas are low-lying at at risk of flooding.  But some other cities are in a worse situation – or should I say, are feeling the impacts sooner.

FLA: the future coastline

Take Southern Florida.  The whole tip of the peninsula is expected to be under water in a few hundred years.  But flooding during high tides is already a common occurrence in places like Miami or Fort Lauderdale.  Indeed, Miami may be the city that is most at risk in terms of financial exposure ($278 billion), even more than other coastal cities such as Guangzhou, New York City, and far worse than better prepared Amsterdam.

Much has been written about flooding in Florida, as any google search will reveal.  I thought I’d go with excerpts of some of the best articles.  For instance, here’s Katherine Bagley (InsideClimateNews) reporting on a flood in Fort Lauderdale (the so-called Venice of America):

Already, water regularly creeps over sea walls, lapping against foundations every few weeks. When the earth, moon and sun align to drive waters as much as 18 inches above normal, the resulting King Tides inundate whole streets and neighborhoods. The city is racing to put climate resiliency measures in place, but they face a nearly impossible foe.

“There are winners and losers,” said Keren Bolter, a climate scientist who grew up here and studies sea level rise. “But in a few decades, most waterfront properties in Fort Lauderdale will flood for days, weeks at a time.”

“See that house right there—the white ranch-style one?” Bolter said one day in late November, during a balmy, sundrenched ride on a yellow water taxi through Fort Lauderdale’s waterways. She glanced at her smartphone to consult a database compiled by her company, Coastal Risk Consulting.  “That property flooded 11 days last year. By the late 2030s it could have water on its property 267 days per year.”

Elizabeth Kolbert visited Miami for the New Yorker.  She writes:

We’d come to a neighborhood of multimillion-dollar homes where the water was creeping under the security gates and up the driveways. Porsches and Mercedeses sat flooded up to their chassis.

“This is today, you know,” Wanless said. “This isn’t with two feet of sea-level rise.” A truck from the Miami Beach Public Works Department pulled up. The driver asked if we had called City Hall. Apparently, one of the residents of the street had mistaken the high tide for a water-main break. As we were chatting with him, an elderly woman leaning on a walker rounded the corner. She looked at the lake the street had become and wailed, “What am I supposed to do?” The men in the pickup truck agreed to take her home.

[In the Shorecrest neighbourhood] the water on the street was so deep that it was, indeed, hard to tell where it was coming from. [UCS researcher Nicole] Hammer explained that it was emerging from the storm drains. Instead of funnelling rainwater into the bay, as they were designed to do, the drains were directing water from the bay onto the streets. “The infrastructure we have is built for a world that doesn’t exist anymore,” she said.

Kerri Sheridan describes a flood in the Keys:

On Key Largo, a tropical isle famous for snorkeling and fishing, the floods began in late September. While people expected high tides due to the season and the influence of a super moon, they were taken by surprise when a handful of streets in the lowest-lying neighborhoods stayed inundated for nearly a month with 16-inches (40-centimeters) of saltwater.

By early November, the roads finally dried up. But unusually heavy rains in December brought it all back again.

It has to be stressed: this is not a freak, once in a lifetime flooding.  It is recurrent, common, predictable even.  Given that, it is surprising that the situation has not yet affected the real estate market.  Continues Sheridan:

For now, south Florida real estate is booming. More than half of transactions are paid for in cash, a sign of the powerful influence of foreign investors on the real estate market.

“So far we have not been seeing buyers being concerned with sea level rise, which I’m a little surprised given all the media attention it has garnered lately,” said Lisa Ferringo, president of the Marathon/Lower Keys Board of Realtors.

Adds Bagley:

“All of South Florida is building like crazy, like there is no tomorrow, which is true, unfortunately,” said Wanless, the University of Miami scientist. “The plan is to build these homes and sell them to the Iowa pig farmer who has worked all his life to retire here, or get a nice investment for his grandchildren. They are being hoodwinked.”

This leaves homeowners and banks on the hook for countless dollars in lost property values.

“If we follow the federal government’s estimates, we could be at 6.6 feet by the end of the century,” Wanless continued. “That curve puts us at 2 feet by 2048. That’s barely a mortgage cycle away.”

Eventually, the market is bound to catch up; insurance may no longer be available, banks may no longer offer mortgages.  This creates a vicious cycle; a lot of money is needed to address the problem.  And there is a gentrification angle, compounding the social issues.  Bagley again:

The good news is that much of Fort Lauderdale’s historically black neighborhood, known as Sistrunk, sits on a small hill a few feet higher in elevation than the wealthy oceanfront areas, said [environmental justic activist Audrey] Peterman. But environmental justice advocates worry that even if these communities are spared the worst of sea level rise, they could still lose their homes as wealthier families look to relocate to higher ground.

“It is climate gentrification,” said Nicole Hernandez Hammer, an expert for the Union of Concerned Scientists on how climate change impacts Latinos in Southeastern states. But in South Florida, with the ocean to east, the Everglades to the west, and sea level rise bubbling up through the bedrock, there will be nowhere else for these communities to go.

But what, exactly, is causing the problem?  Why is Florida so much worse than elsewhere?  Part of the problem is that Florida lies over porous limestone.  Explains Bagley:

Fort Lauderdale can’t take the simpler approach of cities like New Orleans or Amsterdam of keeping floods at bay with levees and seawalls. Like most of South Florida, its porous limestone bedrock lets water creep under and through the foundations of any defense, said Hal Wanless.

Compounding the problem is the issue of fresh water.  As sea levels rise, the water tables also rise, and that means less space to absorb rain water.  It also means that salinity levels are rising in water wells.  But most of the fresh water is at the surface, in the Everglades.  The giant wetland is badly polluted (the sugar industry being a key culprit).  But the main problem is simply that the waters of the Everglades need to flow out – into the coastal areas already besieged by coastal flooding.  Kolbert:

Even today, with the Everglades reduced to half its former size, water in the region is constantly being shunted around. The South Florida Water Management District, a state agency, claims that it operates the “world’s largest water control system,” which includes twenty-three hundred miles of canals, sixty-one pump stations, and more than two thousand “water control structures.”

When the system was designed—redesigned, really—in the nineteen-fifties, the water level in the canals could be maintained at least a foot and a half higher than the level of high tide. Thanks to this difference in elevation, water flowed off the land toward the sea. At the same time, there was enough freshwater pushing out to prevent saltwater from pressing in. Owing in part to sea-level rise, the gap has since been cut by about eight inches, and the region faces the discomfiting prospect that, during storms, it will be inundated not just along the coasts but also inland, by rainwater that has nowhere to go. Meanwhile, what’s known as the saltwater front is advancing. One city—Hallandale Beach, just north of Miami—has already had to close most of its drinking wells, because the water is too salty. Many other cities are worried that they will have to do the same.

What is to be done?  There is little help forthcoming from the State, which has managed to tie itself up in knots between denying the reality of climate change and preventing the growth of the solar industry.  As is often the case, the municipalities are left holding the bag.  Some are coming up with innovative flood management approaches at the local level.  Write Joey Flechas and Jenny Staletovich of the Miami Herald:

The sea started boiling up into the street. A major Miami Beach road was under water. Tourists sloshed to hotels through saltwater up to their shins, pants rolled up, suitcases in one hand, shoes in the other.

But one corner of Miami Beach stayed perfectly dry. In Sunset Harbour, which has historically flooded during seasonal high tides, the water was held at bay last month by a radically re-engineered streetscape that will be put to the test again this week with another king tide.

The design — featuring a street and sidewalk perched on an upper tier, 2 ½ feet above the front doors of roadside businesses, and backed by a hulking nearby pump house — represents what one city engineer called “the street of tomorrow.”

I have reproduced the diagrams that accompany the article, above, and these illustrate pretty innovative thinking.  The problem with this sort of systems, though,  is that they are costly, and their effects are strictly local.  Further, their impact can only be temporary if the seas keep rising.  Continue Flechas and Staletovich:

With flooding growing from occasional annoyance to economic concern, in 2012 the city crafted a bold blueprint for overhauling an antiquated stormwater system that relied on gravity to drain into the bay. Higher tides increasingly backed up the drain pipes and even reversed the flow, turning the system into a conduit to pump seawater up through sewer grates onto heavily traveled arteries like Alton Road.

The new system collects flood waters, screens out large debris like plastic bottles and pumps it back out into Biscayne Bay through one-way valves known as backflow preventers that keep rising Biscayne Bay waters from flooding drainage pipes. The plan also calls for raising seawalls, most of which are on private property, and raising some roads.

But even Mayor Philip Levine, the biggest cheerleader of efforts to “rise above” sea level rise, would acknowledge that pumps alone represent a temporary fix – a 30- to 40-year buffer. If future projections hold true, more roads will have to be raised — along with buildings — as the rising sea pushes up through the porous limestone sponge underlying much of South Florida. First floors might have to be vacated, rusting infrastructure replaced, codes and building elevations dramatically beefed up.

Raised road, patio at original level, Miami Beach

This is a pretty daunting prospect, of course.  But, albeit on a smaller scale, it would not be the first time a city picks itself up and raises itself.  Chicago did exactly that.  The city had realized that, being level with Lake Michigan, it was too exposed to floods, and built too low for its sewers to work properly.  First to be raised, in January 1858, was a four-story brick building that was lifted by nearly two meters above grade.  The operation was so successful that all buildings were similarly lifted.  Roads were then built above grades, with sewers and storm drains below.

Or maybe the future approach could be inspired by harbourfront designs in Hamburg, Germany.  In HafenCity, the concept is to allow the flodd waters in; ground floors are built either to be flood proof, or to let flood waters in in such a way that no damage results.  All the buildings are connected by elevated pedestrian walkways and bridges at first-floor levels, so that occupants and workers can still come and go (and reach dry ground downtown, if needed).  This approach was also to retrofit the nearby Speicherstadt district; the Unesco-heritage site, a former warehouse district, is now home to fancy offices, stores and restaurants that can likewise be reached by elevated walkways in the event of a flood.

Then again, maybe Florida will just keep getting flooded.  Does anyone ever get used to living with repeated flooding?  Floridians may well have to, at least judging by the leadership at state level.  Journalist and author Carl Hiassen parodied governor Rick Scott for banning the words “climate change” from the lips and pens of state employees.  Hiassen:

Please pay no attention to recent news reports about my administration banning the use of the terms “climate change” and “global warming” in official documents, letters or emails. There is no official ban.

All communications among state employees are routinely diverted for review by my staff members who, when appropriate, re-phrase the content.  For example, residents in Miami Beach are blaming so-called climate change for raising the sea level and causing frequent flooding of streets and neighborhoods.

The crisis poses an undeniable threat to the tourism and real-estate industries, and I’ve acted swiftly. At my direction, the state Department of Environmental Protection will henceforth define the situation in Miami Beach as a “permanent high tide.”

Written by enviropaul

April 9, 2017 at 11:24 am