(Internal) Coastal Flooding Community Science 12/23/2022

On the morning of December 23, 2022, a storm bringing strong winds and heavy rain intersected with high spring tides and caused coastal flooding throughout Maine. Gulf of Maine Research Institute is partnering with dedicated community members to combine photographic flood impact data with local water level measurements in Saint George, the Boothbay peninsula, and Portland (learn more about the project  here ).

Historically, how bad was the flooding? The NOAA Portland tide gauge record goes back to 1910, and this storm roughly ties the Blizzard of 1978 for the highest water level recorded at the Portland gauge over the past 113 years (it’s difficult to precisely rank the two storms relative to each other because in 1978, the gauge was taking one water level measurement per hour, and how the gauge measures once every 6 minutes). Sea level rise and the predicted tide were the two big contributors to this flood event breaking records. In Portland,the storm surge itself (the rise in water level from strong winds) was under 3 feet, putting it somewhere between the type of surge we experience annually to once in 5 years. This unspectacular surge, however, happened to intersect with a predicted tide of 11.3 ft above MLLW, which is in the top 2% of high tides in Portland. For context, the January 17th storm this year had a significantly higher storm surge (it was over 3 ft), but it intersected with a lower high tide so didn’t cause nearly the same extent of flooding as this event. If we had not been experiencing sea level rise over the past 100 years, the Blizzard of ’78 would have been the clear flood record-breaker, and this December storm would have been roughly a 1-in-10 year event.

Explore the maps below to see tide gauge data and photographs from the storm. Click the button below to access a document that links to all original images and lists the water level at the nearest tide gauge when each photo was taken.

Explore the map below to:

1) View graphics showing water levels during the storm in Saint George and Portland and where they were recorded

2) Access the real-time water level data

3) See where we plan to install a tide gauge in Boothbay in January 2023

Click on the locations below to view photos of flooding and the associated water level from from the Portland NOAA gauge (Commercial Street sites) or the Back Cove Hohonu gauge (Bayside sites). Water levels are in feet above NAVD88. For the Commercial St. sites, you can add 5.26 ft to convert to ft above MLLW.

Highest observed water levels on 12/23 were at 10:24am (NOAA tide gauge) and 10:36am (Back Cove tide gauge).

Click on the locations below to view photos of flooding and the associated water level from from the Portland NOAA gauge. Water levels are in feet above NAVD88, and you can add 5.26 ft to convert to ft above MLLW.

The highest observed water level was at 10:24am.

Click on the locations below to view photos of flooding and the associated water level from from the Saint George Southern Island Hohonu tide gauge. Water levels are in feet above NAVD88.

The highest observed water level was at 10:36am.

Unfortunately, we experienced technical issues with the Boothbay tide gauge, so we do not have water levels accompanying these photos.