New study: a surge in flooding along the Gulf Coast expected by the 2030s

Due to a combination of a wobble in the Moon’s orbit and continued sea level rise
Hurricane Sally unleashes flooding, hundreds rescued
Hurricane Sally unleashes flooding, hundreds rescued
Published: Aug. 10, 2021 at 10:38 AM CDT
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ALABAMA (WSFA) - A NASA study released in late June paints a problematic picture for coastal communities in the United States. That includes all coasts -- the East Coast, West Coast and Gulf Coast.

The study looks at the impact of sea level rise in tandem with the Moon’s effect on tides here on Earth. The results of the study highlight a problem that will only become worse with time.

The problem? High-tide floods. These are also referred to as nuisance floods or sunny day floods.

These floods occur now, and will continue to occur. They can be impactful and cause problems -- ranging from being an inconvenience to forcing businesses and infrastructure to close. Once we get to the 2030s, though, the impacts felt by these high-tide floods are expected to be significantly worse and much more common.

According to NASA, every U.S. coast will experience rapidly increasing high-tide floods by the mid-2030s.

“For some parts of the U.S. coastline where you’re not seeing flooding, what we’re showing [in] our studies [is] we’re going to go from very little flooding to a pretty rapid increase in flooding,” says Dr. Benjamin Hamlington, team lead of the NASA Sea Level Change Science team. “We’re really looking at rapid increases and pretty sharp increases in this study.”

This is due to the projected sea level rise and a wobble in the Moon’s orbit.

This wobble is perfectly normal and was documented way back in the early 1700s as part of the Moon’s 18.6-year cycle. These wobbles have impacts on the Moon’s gravitational pull, which is the main cause of Earth’s tides.

The half of the 18.6-year cycle when tides are amplified is when this wobble occurs. In other words, during half of the Moon’s 18.6-year cycle we see higher high tides and lower low tides. The other half of the cycle is the exact opposite. We are actually in the midst of a tide-amplifying cycle right now.

The issue is we’re going to have noteworthy sea level rise combined with these higher high tides the next time the Moon enters its tide-amplifying phase in the mid-2030s.

This will lead to the potential for not only more high-tide flooding, but more substantial high-tide flooding. Many areas could be at risk for seeing high-tide floods every 1-3 days, which translates to 10-15 high-tide floods per month.

So while high-tide flooding is usually minor (nuisance) compared to the flooding brought on by tropical systems, getting that kind of flooding a dozen times each month will be problematic in a variety of ways. To name a few:

  • Businesses and their parking lots may be under water much more than they are now
  • Beaches could suffer from more severe erosion
  • Roads and other infrastructure could suffer more often
  • Locations that aren’t seeing high-tide flooding now are going to be at a much greater risk of seeing it down the road

“Along the Gulf Coast, we assess some of these locations will have up to 50, 60, 70 additional days of high tide flooding coming up in these future decades,” Hamlington tells WSFA 12 News. That is 3-4 times as many days with high-tide flooding than what the Gulf Coast is seeing now.

It’s not just the mid-2030s that will see this large number of high-tide flooding events along the U.S. coasts. Each time the Moon is in the tide-amplification phase of its cycle, this will be a normalcy. And as sea level rise worsens, each decade that the Moon is in this phase could very well be worse and worse.

But there’s a caveat with all of this, according to Hamlington. “It’s [all] very dependent on how much of that sea level rise -- that foundational sea level rise -- that we see...that’s really affecting our projections,” he says.

If sea level rise isn’t as robust as the study models it to be by the mid-2030s, then the impacts to high-tide flooding would be less significant. Regardless, Hamlington says it’s important to prepare for more flooding and worse flooding if you’re along the coast. That includes communities and cities that may not see flooding much at all now.

Copyright 2021 WSFA 12 News. All rights reserved.