Field measurements of wave induced sand ripples in three dimensions

An acoustic profiling system designed to measure sand ripples in three dimensions has been developed and successfully deployed on benthic frames at two sites around the UK coast. The system comprises a mechanically scanning pencil beam acoustic transducer mounted on a two axis stepper motor assembly within a fully enclosed oil-filled housing. A pressure sensor, temperature sensor and conductivity sensor are also integrated with the instrument, ensuring the correct speed of sound is used for deriving distance to the bed from the time of flight of the acoustic pulses. Data recorded at two sites using the 3D-Acoustic Ripple Profiler are presented showing tidally migrating sand waves in the first case, and wave induced sand ripples evolving in response to a passing storm in the second.