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:

  • RFID tags were installed in cobbles, and a novel RFID tracking system was developed 
  • Cobbles have been tracked monthly since 2020 using RFID mapping, drone photo mapping, and mobile lidar (a method of determining ranges using lasers) surveys 
  • Cobble movement was integrated with ongoing observations of incident waves, beach morphology, and cobble coverage


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



NOAA, 2020-2022


Additional Info and Publications: 


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