One of my favorite things about living along the coast is that the winter solstice usually coincides with some of the winter’s king tides—the highest tides of the year. While the term “king tide” isn’t scientific, it is used to describe particularly high tide events, caused by alignment of the gravitational pull between the sun and the moon. Tidal changes as extreme as the ones in the last couple of weeks have multiple effects on our coastline, both positive and negative.
As a beach lover, I have always been fascinated by tides. The coastlines I spent the most time on growing up—Maine, Rhode Island and North Carolina—are subject to drastic, noticeable changes. At low tide huge mudflats are exposed, perfect for digging clams. Bays and estuaries can become so shallow that boats are grounded, and the man-made canal my grandparents lived on became impassable, but perfect in my mind for trying to see the alligators that lived along the marshy edges. We were taught early to watch for the change in tides and to pay attention to currents.
If you spend time along the coast, you notice that tides have varying degrees of change. When our planet is closest to the sun in its orbit, as happens every January, and the moon is also closest to us in its cycle, we have extreme high tides like those right before Christmas. These extremely high tides can have damaging effects on beaches and low-lying coastal areas, especially when combined with winter storms.
While the king tides are naturally occurring and predictable, they give us a snapshot of the impact changing sea levels will have on coastal communities over the long term. Extreme tides can also have positive effects on coastal water bodies by washing away naturally occurring berms that close the fresh water off from tidal influence. When estuaries like the Carpinteria Salt Marsh are closed off to tidal influences, oxygen levels can drop, causing harmful alga blooms. When this happens, fish and other aquatic life suffer.
Tidally influenced estuaries, areas where fresh water meets the ocean, are an important habitat for many plants and animals. They provide refuge and are a food source to a large number of animal species, and also act as nurseries for fish and shellfish. The streams that flow into the estuary carry nutrients and sediments from high up in the watershed—too much of either can throw off the delicate balance of the ecosystem. The ebb and flow of tides, especially extreme high tides, helps flush out excess sediments and nutrients. Coastal marshland also helps protect adjacent areas from flooding conditions winter storms can cause, as well as more extreme events such as tidal waves and tsunamis. Plants that live in marshy environments often have intricate root systems which slow the speed of water down, dissipating some of the energy before it reaches land.
King tides will be happening again Jan. 20 and 21. If you didn’t get a chance to check out the high tides during the last week of December I highly suggest you see them later this month. Be sure to observe how high the water level in the marsh gets and how the tide effects erosion on the beaches. High tides all over the world are tracked by scientists with the help of citizen volunteers in an effort to predict the future impacts of sea level rise. For many years, sea level rise has been tracked by the National Oceanic and Atmospheric Administration (NOAA).
Contrary to what many people believe, sea level change is not uniform. The ocean, like the land mass of our planet, is and has always been a constantly changing environment. Some areas of the planet have seen relatively drastic changes in sea levels over the last 50 years, while others have seen minimal change. The coast of California, like many ocean-facing regions of the planet, is starting to see a greater change in sea level. Tracking the extreme high tides helps officials anticipate flooding conditions before they happen, allowing communities like Carpinteria to better prepare for what will happen as sea levels change.
If you are interested in becoming involved as a volunteer, visit the California King Tides Project website at coastal.ca.gov/kingtides/index.html.