Smart Pebbles


Smart Pebbles are tracers composed of RFID tags installed within beach pebbles.
The RFID technique is an inexpensive and reliable methodology that is used to address sediment displacement along the coastline.
The use of low-frequency radio signals (125 kHz) enabled the detection of the marked pebbles within a range of 40 cm on the underwater and subaerial portions of the beach.
Hundred of very low cost Smart Pebbles get sampled on the beach and paired with passive transponders. Then they get released on the beach and recovery campaigns take place to track pebbles movements and changes in shape. This allows to study the morphology of the beach and the way it gets eroded.

Monitored Parameters:

  • Shoreline
  • Hazards:

  • Coastal erosion
  • ✓ Relevant to WP3 models ✓ Relevant to the EWSS


    Minimum Quantity : 100


    Sensor Properties
    Accuracy (error of the measurements) Unit of measurement Data Refresh Time (mins) Wi-Fi Connection 4G Connection External Power Supply Documentation
    50 cm cm None False False False See available docs for Smart Pebbles
    Reference Partners Project Name Project Year Reference Paper Minimum Purchase Spatial Density
    MBI/UCD/ATU not stated 2012 Reference paper 100 100
    Purchase operations complexity Assembly/Calibration Operations Complexity Deployment operation Complexity Deployment Cost Data Analysis Operations Complexity
    Neutral Easy Low Difficult
    Citizen Science Activities Complexity Assembly Public Involvement Deployment Public Involvement Data analysis Public Involvement Target Users
    Very easy Medium: pebbles each pebble must be prepared, i.e., 1) drilled with a drill press to insert an RFID tag and then closed with some glue or resin; 2) 3D-scanned to register its shape. A single campaign on a tens to hundreds meter long beach typically requires 150 - 200 pebbles. Vocational schools can be involved in these activities High: citizen can be asked to scatter the prepared pebbles on a beach Limited: only trained citizen can use the probes for campaigns of smart pebbles detection, that can extend to underwater parts of the beach, exactly pinpointing their position. Then, the collected pebbles must be again 3D-scanned to quantify abrasion; finally, data processing on retrieval potitions and abrasion must be processed by researchers. local groups; local authorities; schools


    The cost includes the preparation, deployment, and recovery of the pebbles.

    They are basic pebbles (10-20 cm) collected from the studied beaches, they are drilled to place into them a small device equipped with an antenna and an internal memory, which allows us to track and recognise them.

    The equipment needed is a drill, possibly a pillar drill, to drill the pebbles. Once drilled, place the tracking device inside the pebbles and seal the hole with cement.

    At any time, but summer because the presence of bathers make the operations way harder. The best moment is September/October because it allows us to carry out short-term (recovery after 24/48h), medium (recovery after ⅔ months) and long-term (recovery before the next summer session) experiments.

    Placement is rather quick: it takes a morning.

    It must not rain and the sea must be calm.

    Once recovered the pebbles will be weighted, measured and 3D scanned, to keep track of abrasion phenomena.

    Talking about the short-term experiment, everything can be carried out in a matter of two weeks (considering the preparation of the pebbles, their positioning, recovering and following activities). For the medium and long-term experiments the two-months pauses between one campaign and the other.

    The main risks concern the drilling phase of the pebbles, which require the use of the drill with all the risks that this implies. Otherwise, there are no particular risks.

    Additional pictures