The moon takes 18.6 years to orbit the Earth. Half the time, depending on the moon’s location, high tides are suppressed, and low tides are higher, and the other half, low tides are lower, and high tides are higher. In other words, if you have a sandbar off the coast, depending on the cycle the moon is in, you’ll see more of it at low tide.
Apparently, the scientific term for these phases is “wobble.”
Currently, the moon is in a higher high tide mode. Sea levels in the U.S. haven’t risen much in the past decade, so there is no cause for concern of dramatic flooding. It won’t return to this tide-amplifying cycle for another decade, and by then, experts predict the seas will have risen enough to cause more nuisance flooding along Virginia’s coast.
What is Nuisance Flooding
Nuisance flooding is minor tidal flooding that occurs at high tide, characterized by overtopped sea walls, water in low-lying road areas, and water systems that have water coming out through intake pipes. If you’ve ever been in Virginia Beach during a rainstorm at high tide, you have experienced nuisance flooding.
According to Billy Sweet with NOAA’s Center for Operational Oceanographic Produce and Services, “Nuisance flooding is becoming more of an issue in the Mid-Atlantic. It is a hot spot where we have the highest frequency of these types of events.” You can learn more about how NOAA works with localities to help manage nuisance flooding events here.
The 2030s Are Looking Tough For Coastal States
In 2019, NOAA reported more than 600 floods in the U.S., primarily along the East Coast. By the middle of the 2030s, scientists expect there to be more than 900-1200 floods due to rising sea levels and the return of the moon’s wobble, tide-amplifying phase.
“Low-lying areas near sea level will be increasingly at risk and suffering due to the increased flooding, and it will only get worse,” according to NASA administrator Bill Nelson.
A recent study published in the Nature Climate Change journal by NASA Sea Level Change Science Team from the University of Hawaii states that floods in the 2030s could happen in clusters and occur for more than a month. The positioning of the moon, sun, and Earth could mean flooding in cities that last several consecutive days or every few days for extended periods.
How This Affects In-land Flooding
Nuisance flooding from high tides doesn’t affect only coastal areas. During heavy downpours upstream, water can get pushed back during high tides as the ocean moves inland. This makes it harder to get run-off into the rivers in a storm as their levels rise too and push against the water heading downstream.
“If it floods 10 or 15 times a month, a business can’t keep operating with its parking lot underwater,” said Phil Thomson from the University of Hawaii. “People will lose their jobs because they can’t get to work, and seeping cesspools will become a public health issue.”
Depending on demand and availability, materials for repairing flood damage will become more costly across the country, impacting Virginia homeowners and insurance companies.
“Insurance premiums are based on the replacement value of a home. If building materials and labor are in high demand and costs increase, premiums will likely rise due to price inflation,” according to Mark Crutcher, Vice President of Marketing and Innovation at Mutual Assurance.
NASA hopes that by releasing the results of their study now, at-risk cities in Virginia and other coastal states can take measures to address infrastructure issues and mitigate damage.
Sources: NOAA, USA Today