A friend recently asked me, "so, are you bullish on Miami yet, or are you still worried about the water?" And my response was that I love Miami, but that I do think about the risk of climate change.

Then today, another friend sent me this study by scientists at the University of Miami showing that 35 buildings along the Miami Beach to Sunny Isles Beach coastline experienced some degree of subsidence between 2016 to 2023. In other words, they sunk into the ground a little.

Here's how they measured this:

The study published December 13, 2024, in the open-access journal Earth and Space Science, of the American Geophysical Union, employed a satellite-based technique known as Interferometric Synthetic Aperture Radar (InSAR). By combining 222 SAR images from the European Sentinel-1 satellites, the research team created a surface displacement time series. The technique utilizes "persistent radar scatterers" as reference points for measurement. These scatterers include fixed elements on a structure such as building balconies, rooftop air conditioning units, and boardwalks, which reflect the radar signal back to the satellite antenna. Satellites flying at 700 kilometers above Earth can measure millimeter-scale displacements.

Now, some degree of subsidence is normal. But apparently, not this much:

“The discovery of the extent of subsidence hotspots along the South Florida coastline was unexpected,” said Farzaneh Aziz Zanjani, the study’s lead author, a former post-doctoral researcher and alumna of the Rosenstiel School. “The study underscores the need for ongoing monitoring and a deeper understanding of the long-term implications for these structures.”

So yeah, I'm still worried about the water. It's something I would need to get a lot smarter on in order to feel comfortable.

This beach area was closed because of high winds and choppy waters. But that didn’t stop these kids from doing some very impressive dives off of this ledge. It also happens to be right beside a wonderful restaurant / diving facility called Le Plongeoir.

I spent a good chunk of this morning talking and thinking about underground building details that most people (unless you're in the industry) would never think to consider. This is not a criticism on most people. I mean, I don't know how iPhones are made. I just use and enjoy them. But when it comes to buildings, I'm paid to ask questions and understand how things work.

There's a lot of risk in the ground.

You have to think about things like bearing capacity, environmental contamination (usually), hydrostatic pressure and, generally, how you're going to manage water, particularly if you have a high groundwater table. Usually this last one is about making sure you're keeping the water out. A pretty important detail both below and above grade.

So when I came home tonight and saw the below tweet, I felt obligated to write about it.

If you read the reply from NYC's Metropolitan Transportation Authority, you'll see that this is them testing something they call a "flex gate." It is a flood barrier that allows them to seal off subway entrances in the case of a storm surge and they run these tests (shown above) for 4 hours at a time to make sure they're installed property. This one was.

Managing water is a big part of city building. New York City, Miami, Venice, and countless others know this all too well right now.