September 2010 home page

  Coast Watch: Sand Chronicles
Jon Edelbrock | Del Mar Life Guard Sergeant

Winter Beach 2009.  Photo Art Olson

Have you ever noticed the varying sand levels at the beach throughout the year? Beach sand is in a constant state of flux along our coast, dancing between a state of eroding and depositing on the shore for visitors to enjoy. This natural process, dictated by Pacific Ocean storm activity, is often at odds with development and erosion mitigation efforts.

Coastal communities in Southern California have been attracting visitors with their beautiful sandy beaches for years. Attractive beaches produce increased tourism, property values, hotel occupancy, and sales tax revenues. Sand has become a commodity. Losing sand depresses many economic factors contributing to a thriving beach community.

Scientists have documented a coastal bluffs erosion rate of about a quarter inch per year. With up to fifty percent of our beach sand subject to this erosion, one would think that our sand levels would be in great shape. We have, however, seen otherwise due to river damming efforts, lack of sand transport from sea walls to our north, and just plain bad luck.

The luck part of how much sand we have come summertime is a big one for those of us who watch the sand shift each day. While most measurements are at longer intervals, daily beachgoers and lifeguards see the daily shift in sand levels.
The past two summers have produced a visibly narrower beach. Much of our sand comes in spring months as high-energy winter storms from the northern Pacific Ocean give way to lower energy storms from the southern Pacific. The less energy from the combination of waves and wind, the more depositing we get. The last few years have produced multiple late-season tight wave interval Northwest swells that coincided with our highest tides, creating a perfect storm for sand erosion.

For many years, mitigation efforts have attempted to decrease erosion, capture existing sand, protect structures, and re-locate beach quality sand. While none of the efforts has proven effective alone, our city has taken aggressive steps to protect personal property, city property, and the coastal bluff in front of Powerhouse Park, constructing sea walls and using sand and rip-rap to help lessen the energy and scouring of the bluffs.

Regional efforts are ongoing to preserve our coastal natural resources and find solutions to meet the needs of local economies, property owners, and environmentalists. With much of the lure and beauty of Del Mar based on our local beach, sand erosion will likely be on our community agenda well into the future.


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