Tides of the Future Seen Today

By Ciaran Gallagher, CivicSpark Fellow

What will the high tide look like in 2050 considering the rising seas? Looking at GIS maps or making a visual estimate from a normal high tide is nothing like seeing the actual water inundation. When the moon is closest to the earth, it is called a supermoon and its gravitational pull creates high tides known as King Tides. These typically occur in December and January and give us a glimpse of what a normal high tide in 2050 will look like.

When the City of Hayward staff and CivicSpark fellows arrived at the Hayward Shoreline Interpretive Center at 10am on January 2nd, we could hardly imagine the water level reaching the San Francisco Bay Trail in just a few hours. The tides would have to rise more than a foot in less than two hours. The only indication this would happen was the water mark from the previous high tide, about 12 hours prior.

We gathered at the Hayward Shoreline Interpretive Center for the Hayward Area Shoreline Planning Agency (HASPA) meeting. After 90 minutes, the meeting adjourned and we all walked into the crisp brisk air on the Interpretive Center’s deck. We were shocked to find water completely covering the plants in the marsh that were visible just over an hour before. At this time, water was still flowing in from the Bay, slowly creeping up to the Bay Trail’s edge.

More Hayward City staff arrived with two drones in hand to capture aerial photographs of the inundated marshland. They were also able to measure the difference in water height between a normal high tide and the King tide by comparing aerial photographs of the two events. Add height measured.

Artistic signs were installed years ago on a piling of the Interpretive Center indicated the predicted normal high tide for 2050 and 2100. The King Tide reached and began to cover the 2050 mark. As we watched the water flow by, we began discussing how the building in front of us would flood if there was a combination of a storm surge, a King Tide event, and heavy rainfall. It just takes a one-time event lasting only a few hours to flood and cause significant damage to a building near the shoreline.

The King Tide in January 2017 completely covered the San Francisco Bay Trail in Hayward. Although this year’s King Tide did not flood the trail, due to other factors like barometric pressure, we could clearly see the vulnerability of the Hayward shoreline. Earlier in the day, HASPA had discussed progress on the Hayward Regional Shoreline Master Plan which will outline adaptation measures that can be taken to prepare for and mitigate against sea level rise. Watching the King Tide simply reinforced the necessity of this long-term adaptation plan.

HASPA will next meet on April 12th at 3pm at the Hayward Shoreline Interpretive Center.


Aerial photograph during the high point of the King Tide on January 2nd, 2018

 


Close-up aerial photograph of San Francisco Bay Trail and Hayward Shoreline Interpretive Center