King Tides Are Here! Help Document Them

By Ruby Pap

Satellite observation of sea surface anomalies in the Pacific in April 2017. See http://uhslc.soest.hawaii.edu/sea-level-forecasts/ for more info and images.

Have you noticed higher than normal tides lately? No, you didn’t read the tide charts wrong — for the last year or so the islands have been experiencing tides that are higher than predicted. The University of Hawai‘i Sea Level Center website states Hawai‘i is experiencing “exceptionally high sea levels,” April being particularly high with more than 17 cm (6.7 inches) above normal based on satellite altimetry measurements.

Confusing? The first thing to understand is that sea levels are not uniform across the world’s oceans — the sea is actually “bumpy.” According to Hawai‘i Sea Grant, which has a webpage explaining the phenomenon; astronomical, climatic and meteorological factors all contribute to water levels, which include such things as daily tides, king tides, El Niño, or storm surges. Also, sea surface anomalies or bulges can track across the ocean. A good way to visualize this is through satellite altimetry, which maps the sea-surface anomalies.

Predicted versus observed tides at Nāwiliwili tide gauge, Kaua‘i for the month of April. Blue line indicates predicted tide. Green line indicates the actual observed water levels.

Experts point to the waning El Niño as the driver for Hawai‘i’s current elevated seas (related to warmer surface waters), but it is surprising that they have persisted this long after its peak in Winter 2015/2016. Some wonder whether these sea levels have become the “new normal” in the face of climate change and sea level rise. The UH Sea Level Center predicts elevated sea levels around Hawai‘i are likely to continue for the next six months or so, potentially enhancing extreme high tides (or king tides) during June and July.

Besides being an anxiety-producing brainteaser, our current elevated ocean and upcoming predicted King Tides provide a good opportunity to photo document the impacts that will likely become a more regular occurrence with sea level rise.

Niumalu, Kaua‘i during King Tide on 7/30/15. Compare this to the same image at low tide. Credit: Carl Berg

Concerned about a particular section of roadway, harbor infrastructure or coastal agriculture? King tide events are an important time to document how flooding occurs over time. This is where the Hawai‘i Sea Grant and Pacific Islands King Tides Project comes in.

The King Tides project is looking for everyday citizens, business owners, government workers, students, anyone with a camera, really, to photo-document different areas of the shoreline during king tide events.

The method is simple and fun (especially if you have a smart phone). See pacificislandskingtides.com for detailed instructions.

Niumalu, Kaua‘i at low tide on 7/30/15. Compare this to the same image during the King Tide. Credit: Carl Berg

Step 1: Pick a coastal site (or as many as you want), preferable one that you know is low-lying or prone to flooding, and one that has an easily identifiable feature such as a wall, a pier or other structure.

Step 2: Plan your photo survey by checking the king tide dates and times for your area. The next king tides dates for Kaua‘i are June 23-24 and July 21-22 (be sure to check specific times for high tide in the detailed instructions).

Step 3: Sign up at https://getliquid.io/home and join the Hawai‘i and Pacific Islands King Tides online dataset.

Step 4: Download the mobile app on your smart phone (search for “liquid mobile” on iPhone or “liquid field notes” on Android).

Step 4: Show up at your site at the high tide time identified in Step 2, take pictures, and upload them to the app

Ruby Pap

Voila! An easy way to volunteer, at the seaside, on beautiful Kaua‘i, with plenty of time left for the rest of your day. If you are at all interested and need help getting started, please contact me so I can track how many folks will be out on Kaua‘i. I have a minor competition going with the other islands, and we know we are the best island, don’t we?

Visit http://ccsr.seagrant.soest.hawaii.edu/Hawaii%20Sea%20Level for more information.

• Ruby Pap is a Coastal Land Use Extension Agent at University of Hawai‘i Sea Grant College Program. She can be reached at rpap@hawaii.edu.