Achelous 

  • Ultrasonic streamflow sensors are often used to measure stream and river velocity.
  • These conventional sensors are installed in the channel and are therefore prone to destruction during high-magnitude discharge events.
  • Achelous utilizes an array of ultrasonic sensors situated in the air above a river channel.
  • Time-of-arrival differences between transducers and Doppler shifts from water surface reflections are used to measure stream velocity and stage.
  • A novel algorithm is used to correct for temperature gradients above the river channel that influence the measurements.
  • The first prototype was finished in May of 2019 using 3D designed and printed parts in the SWSL lab.
  • Further development of the circuit to have the ability to measure hydroclimatic variables is being conducted.
  • An initial prototype of the sensor was tested at Marmot Creek, Alberta and a prototype of the system is slated for deployment on the Borden Bridge near Saskatoon.
  • Developments to this sensor since first prototype include a higher SPL (sound pressure level) by increasing the peak-to-peak voltage across the ultrasonic transmitting transducer so that distance, river stage, relative humidity, and air temperature measurements can be made effectively over the distance above the water surface. 

 

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 Achelous sensor with 3D printed enclosure showing multiple transducers

 

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Initial prototype of Achelous sensor tested on Marmot Creek, Alberta.  Also visible in the image is a commercial ultrasonic depth sensor and a shielded temperature / RH sensor for comparison measurements.