Thread by @MiamiHerald

IN TODAY’S MIAMI HERALD: Our reimagined newspaper features an in-depth look at an often ignored and little understood enemy in South Florida — groundwater. 🧵

Scientists say there is now enough data to show that rising groundwater levels will add to flood risks for South Florida — particularly in low-lying or coastal areas that already see repeated problems during heavy rains, like Little River and North Miami. miamiherald.com/news/local/env…

And new studies, like one charting sharp increases in sea rise at the site of Champlain Tower South, point to potential concerns beyond flooding.

This emerging research raises questions about the impact of rising seas and groundwater on coastal construction, especially for aging high-rises whose stability depends on ramming giant cylinders of concrete and steel hundreds of feet below the surface.

The Surfside tragedy was a bellwether moment in many ways, elevating climate change concerns and questions with policymakers, the public and researchers.

Mike Sukop, a hydrogeologist at @fiu, is one of the groundwater experts on a first-of-its kind research proposal. His previous research in North Miami found that groundwater is rising at nearly the same rate as sea level in low-lying spots in the county.

@FIU “It seems really important to me,” he said of the potential looming threat down the road for many areas of the county. “The risks from it seem pretty substantial.”

@FIU Throughout most of Miami-Dade, there’s an average of five feet between the ground and water underneath during the wettest time of the year — October. But in coastal, riverfront and far western pockets of the county, that number drops to under three feet.

@FIU Current predictions show Miami-Dade could see around two feet of sea level rise by 2060. And research done by FIU scientists in North Miami, one of the areas where groundwater levels are already high, shows that groundwater is rising at the same rate as the sea.

@FIU The study projects that sections of North Miami could go from experiencing about three months of rain-driven flooding a year now to six months a year by 2060.

And that was considered a conservative estimate.

@FIU Groundwater has long been a construction challenge in South Florida — and one reason, along with drainage from storms, that some underground parking garages need periodic pumping.

@FIU Late last year, contractors digging the deepest underground garage in Miami hit groundwater. The giant pit set to one day become UNA Residences, a 47-story luxury bayfront condominium, quickly filled to the brim with murky water.

@FIU A change in inspections is likely the first step to seeing new buildings built to better withstand rising groundwater.

@FIU Research from a 2019 FIU study showed that groundwater levels will likely rise along with sea levels and suggested a slew of changes, including raising all buildings another foot, but the building commission has yet to adopt any of the suggestions.

@FIU The next year, the building commission decided, moving forward, to only fund research into the impacts of hurricanes.

@FIU Parkinson said he worries that even when future inspections identify problems, it will be years before the building community adapts to it, leading to hundreds or thousands of new, unprotected buildings being built in the meantime.

@FIU Whether rising seas played a role in the collapse of the doomed Surfside condominium is unclear — and perhaps, unlikely. miamiherald.com/news/local/env…

@FIU But the new research from FIU provides the data for what regular passers-by have witnessed in the now-empty parking garage floor — water rises and falls not just with rain but with the tides.

@FIU Parkinson compared the elevation of the garage flood with sea levels from monitoring stations in Miami Beach.

@FIU He found water levels were higher than the garage floor about 244 times a year between 1994 and 2006. From 2007 to 2020, that number nearly tripled to 636 times a year.

@FIU That means that in the most recent decade, sea level was above the Champlain garage floor nearly every day at both high tide events. Add in groundwater, freshwater that floats on top of saltwater that has pushed in along the coast, and the flooding potential virtually doubles.

@FIU “It’s pretty mind-boggling,” Parkinson said.

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