WILMINGTON, Del. — Coastal residents will get a preview of future sea levels when a “king tide” occurs as far inland as Philadelphia and Trenton during high tides on Wednesday, Thursday and Friday.
The tidal Delaware River and Bay, otherwise known as the Delaware Estuary, is no stranger to tides. What makes a king tide unique is its height: a foot or more above normal high tides due to astronomical factors. This can be amplified in Delaware Bay given how it narrows like a funnel as tides move upstream. King tides can also be dangerous when combined with storms like nor’easters that bring winds and heavy rain.
“What’s interesting about king tides is how they serve as a window into our future,” said Dr. Danielle Kreeger, science director at the Partnership for the Delaware Estuary. “Today’s king tides will be tomorrow’s daily tides, probably in about 20 years. Most experts believe that sea levels in the Delaware Estuary will rise by three to five feet this century.”
The Partnership for the Delaware Estuary recently published a new resource for community leaders dealing not only with surging tides, but also with flooding and record rainfall. This booklet is entitled “Weathering Change,” and it details different ways people can work with nature for the benefit of neighborhoods and clean water. Examples include protecting wetlands; installing natural, or “living shorelines;” and planning smart developments, or those that absorb runoff rather than contribute to flooding.
With the approach of both Halloween and the king tide, the Partnership for the Delaware Estuary has created the first-ever, king-tide crown. The crown is free and available for download at DelawareEstuary.org. The PDE has invited its supporters to post pictures on its facebook page featuring their local king tide or themselves wearing a king-tide crown.
Similar king-tide projects are taking place elsewhere. These include Barnegat Bay in New Jersey and Puget Sound in Washington state. In each case, the goal is to educate locals about the future of their coastlines.
Most people are familiar with tides, which flood and ebb along the East Coast twice a day as the Earth spins on its axis. Far fewer people are familiar with king tides. Like normal tides, king tides occur when the moon’s gravity pulls at the water in our oceans. What makes a king tide higher or lower is the added pull of both the sun and moon together. This occurs when the Earth reaches its closest point to the sun during its annual orbit and the moon reaches its closest point to the Earth during its 27-day orbit. The two combined make for water levels both higher and lower than daily tides and bi-monthly spring tides.