LIHUE — A swell will be arriving with the highest water levels of the summer late this week, and experts say tides could rise up to a foot above normal.
On Kauai, that means low-lying areas like Hanalei and Kukuiula could be at risk for flooding, according to experts.
The change in tide levels isn’t new. The events are known as “king tides” and they occur annually over a few days around May 26, June 23, and July 21 in Hawaii.
The last king tide in Hawaii was on April 28, when the highest water levels in 112 years were recorded. Water washed across lawns, crossed roads, and waves slammed into retaining walls on Oahu and levels rose nine inches above predicted heights.
Officials from the Kauai Emergency Management Agency said they didn’t receive any reports of damages or flooding from the April event on Kauai.
“I remember a couple of years ago there was a king tide and the dock at Nawiliwili Harbor was awash,” said Chip Fletcher, associate dean of the University of Hawaii School of Ocean and Earth Science and Technology. “Water was coming up the boat ramp and above the top.”
Coastal areas on Kauai could be the most at risk starting Wednesday.
“High tides at the end of the day, in the late-ish afternoon, will be rising throughout the week,” Fletcher said.
And while the king tides are set to reach their peak on Friday and then wane on Saturday and through the weekend, a southern swell is winding up and should be hitting the South Side on Friday.
Other contributions are the ocean eddies around Hawaii and the climate and sea level changes associated with last year’s El Nino event.
“It’s stacking a lot of different factors together,” Fletcher said. “It looks like there are waves scheduled to arrive Friday and that will push up the water level as well.”
The National Oceanic and Atmospheric Administration tide stations around Hawaii show that observed water levels have been three to six inches above predicted tide heights since early 2016, according to the UH Sea Level Center.
Those water levels are predicted to rise as much as a foot at their peak by Friday and the UH Sea Grant Center for Coastal Climate Science and Resilience has predicted these unusually high tide levels will continue through the summer.
“The exact amount (of water level rise) will depend on the waves, and we do see the waves mostly coming on Friday,” Fletcher said.
County officials recommend those who live or work in low-lying areas that are prone to flooding to move electronics and other belongings to the second floor of buildings. In addition, businesses should move chemicals and hazardous materials out of flood prone areas.
If heavy rain is forecasted combined with high tides, it could result in rivers flooding and hazardous driving conditions according to Kauai Emergency Management Agency officials. In addition, anyone considering going to the beach over the weekend should be aware that there is a possibility of stronger than normal currents and rip currents, and should check with a lifeguard prior to going into the water.
“It’s impossible to predict the exact effect,” Fletcher said.