First study to track beach cobbles and their influence on beach stability

Cobbles—2.5 to 6-inch diameter stones—naturally stabilize many California beaches. They have been used to construct artificial protective berms and will increasingly influence shoreline change in the face of sea level rise. However, the distribution of cobbles in space and time and the dynamics of their motion are poorly understood. University of Southern California (USC) Sea Grant funded a study using a new radio-frequency identification (RFID) technology to track individual cobbles at Torrey Pines State Beach in San Diego County. This study will provide the first quantitative analysis of cobble movement and help inform the use of cobble as a potential natural shoreline stabilization method in the face of erosion and sea level rise.

Key Results:

  • Hundreds of tagged cobbles were released on a California beach and tracked for 26 months.
  • Cobble movement exhibited complex patterns. Cobble displacement increased with wave energy and detection rates generally decreased with time. Cobbles high on the back of the beach were relatively stable compared to lower-elevation cobbles. More than half of all cobble detections were within 50 m of the initial release location. 
  • The research proved the effectiveness of this novel RFID as a tracking tool and was published in the Journal of Geophysical Research: Earth Surface

 

Project Impacts & Application:

  • Presented at the Torrey Pines Docent Society, Scripps Institution of Oceanography, and the Osher Lifelong Learning Institute
  • Shared results during meetings with California State Parks Managers and the California Coastal Commission
  • Provided a briefing to the Office of Management and Budget, Executive Office of the President
  • Featured on CBS 8 News, San Diego 

 

Principal Investigators:

  • Adam Young, Ph.D., University of California San Diego 
  • Mark Merrifield, Ph.D., University of California San Diego
  • Mark Dickson, Ph.D., University of Auckland, New Zealand

 

Funding:

NOAA, 2020-2022

 

Additional Info and Publications: 

 

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