Mainland Miami ponders demolishing neighborhoods and abandoning them to the sea.

David Smiley has a much read piece in the Miami Herald on the City of Miami’s planning process on how to survive rising sea impacts for another 40-60 years. In Miami Beach, pumps have been installed and roads and sea walls raised to fight the encroaching waters from Biscayne Bay. But Smiley reports that mainland Miami is contemplating a totally different strategy. Instead of resisting the inevitable flooding like the barrier island is doing, it may be best to accommodate the rising waters within urban neighborhoods. 

Due to the unravelling of Antarctica, sea levels are now predicted to reach up to 6 feet along the Florida coast by 2100. The author notes that east of a coral ridge (elevation 18’) the elevation is 3 feet or less. One of the ideas being floated is demolishing properties in the most vulnerable flood zones and returning these developed areas back to the sea. The article quotes Jane Gilbert, chief resilience officer as saying “We need to live with water.”

Last year, the county partnered with the Urban Land Institute to study the region’s vulnerability to climate change. A series of solutions emerged from that study, including a proposal to slowly purchase and demolish properties in areas that repeatedly flood and slowly return them back into a marshy, meandering slough.

Though unfunded, the idea isn’t too farfetched: In 2014, 13 property owners asked the county to help them raze and rebuild their houses.

But in a region reliant on real estate values and development growth, talk of buying out homeowners to build marshes isn’t as easy to digest as simply paying for pumps. With little appetite for eminent domain or raising taxes, homeowners will have to want to sell and government will need to find the money to buy.

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“When people see we’re taking concrete action to actually deal with the stresses of climate change and sea level rise in a sample community like this and we are successful and learning, confidence builds that maybe we can stay here another 50 or 60 years and stay out of harm’s way,” she said. “This is where the tide will turn.”

From the Urban Land Institute report:

A Signature Green Space:

The City Slough Sloughs are low-lying, marshy sites that channel water at a leisurely pace. Characteristic Florida habitats, sloughs can be found throughout the Everglades and connected the Everglades to the Atlantic before Miami was urbanized. These freshwater ecosystems allow slow water movement and provide habitat for a range of species.

In the 19th century, Miami was largely undeveloped, which allowed the natural contours of the land to sustainably handle the movement of water. Aerial photos of Miami’s initial development show Flagler’s railroad along the highest ground and natural systems such as Arch Creek continuing to function. However, speculative development in the 20th century ignored these natural geographic considerations, putting people and property in harm’s way. Neighborhoods such as Arch Creek Estates sprang up in low-lying areas, with buildings constructed before FEMA elevation requirements were in effect. The impervious surfaces of the roads, roofs, and parking spaces led to decreased water infiltration and water quality, as well as increased flooding risk during routine and exceptional rainfall and storm events.

A 21st-century solution would balance the needs of people, water, and nature, creating green spaces in the neighborhood that could make the most of the land’s natural abilities while improving quality of life for local residents. Specifically, transforming the historic creek corridor into a “city slough” over the long term would create a signature green space in Arch Creek that could improve the area’s flood capacity and become neighborhood green space as a focal point around which future development could occur.

The Architects Newspaper weighs in on the inland areas of Miami-Dade and Broward counties.

Because saltwater rises up through South Florida’s porous limestone bedrock, it’s not just coastal communities that are at risk. Many of the most threatened areas lie miles inland, in suburban and often low-income areas of Miami-Dade and Broward Counties that can’t afford to elevate all their homes and streets.

“It’s unavoidable that there will be relocations,” said Anthony Abbate, an architect based in Fort Lauderdale in Broward County, just to the north of Miami-Dade. “It’s a difficult conversation but I think we’re on the verge of having it. This has to be a conversation with the people, with the public.”

Miami-Dade is in the middle of a vulnerability analysis for major infrastructure, from its airport to its water system, identifying “adaptation action areas” where city planners might best focus their efforts.

“There’s a lot of work that needs to be done and it needs to be done in short order,” said Abbate.

The Atlantic Oceanographic and Meteorological Laboratory reports on a ongoing study focusing on contaminants lurking in urban tidal flooding. 

Tidal flooding from events such as the so-called “King Tides” and “Super Tides” are flooding urban coastal communities with increasing frequency as sea levels rise. These tidal flood waters can acquire a wide range of contaminants and toxins as a result of soaking in the built environment of urbanized coastlines. A multi- institutional, interdisciplinary research team, including scientists from AOML, is examining the types of contamination picked up from the urbanized coastal landscape and transported into coastal waters through tidal flooding.

For the past 3 years, a team of microbiologists at AOML has been investigating the types of bacterial contaminants, including fecal-indicating bacteria and disease-causing pathogens, carried back to the marine environment from tidal flood waters, causing potential exposure to both human populations and marine habitats such as coral reefs, beaches, and estuaries.

The AOML team once again investigated contamination from tidal flooding in southeast Florida communities during the recent King Tides of October 17-18, 2016. They were joined by the investigators from Florida International University, the University of Miami, and Nova Southeastern University in measuring bacterial levels, nutrient levels, and selected chemical contaminants in the tidal flood waters and receiving environmental waters from urbanized South Florida communities such as Miami, Miami Beach, Fort Lauderdale, and selected cities in the Florida Keys.

Scientific American reports that climate change will become a factor in gentrification of poor and working class neighborhoods on higher ground. The article titled “High Ground Is Becoming Hot Property as Sea Level Rises” notes the following:

One of the great ironies of those historic housing patterns in Miami is that for decades under Jim Crow, laws and zoning restricted black people to parts of the urban core, an older part of the community that sits on relatively higher ground along a limestone ridge that runs like a topographic stripe down the eastern coast of South Florida. Now, many of those neighborhoods, formerly redlined by lenders and in some places bound in by a literal color wall, have an amenity not yet in the real estate listings: They're on higher ground and are less likely to flood as seas rise.

Whether it's climate change or an eye for good real estate returns, historically black communities on higher ground are increasingly in the sights of speculators and investors. Real estate investment may no longer be just about the next hot neighborhood, it may also now be about the next dry neighborhood.

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In the short term, the biggest threat to Florida's long-term existence in the context of sea-level rise is also one of its most familiar threats: a big hurricane like 1992's Andrew or 2012's Superstorm Sandy.

"What will happen, more than likely, is that you'll have one big hurricane, and you'll get a big inundation into the city," Purkis said. "And that will serve to rot out the infrastructure — the sewer lines, the electricity, the telecoms. Everything that's under the road. That becomes very costly to keep replacing every time this happens."

But higher ground won't be pleasant with "all of the rotting detritus and just general mayhem that that's going to cause," Purkis said. "So by the time the city starts to flood, it's probably not great to be in the high areas either."