Flowing Waters - Special Constructions

Contactless Flow Measurement on Fish Ladder

Contactless Flow Measurement on Fish Ladder
View of measurement place
Contactless Flow Measurement on Fish Ladder


  • Concrete intake channel
  • 3.0 x 2.0 m (w x h)
  • Part filled
  • Gravel bed

Definition of tasks

  • Flow measurement to ensure a minimum water volume required for the fish ladder
  • No sensors can be installed on the channel bottom
  • Contactless measurement if possible on inaccessible point (risk of vandalism)
  • Medium accuracy requirements
Installation principle
Installation principle
Installation principle


  • A contactless surface radar system Type OFR was installed in the fish ladder approach under     a bridge.
  • The System measures the speed of surface waves resulting from the roughchannel bottom (gravel bed). The current flow rate is calulated from this velocity and the current flow level     which is measured contactlessly as well.
  • The flow rate is passed on as mA signal to a PLC on site which controls the position of a slide valve upstream of the measurement point


  • Contactless measurement system
  • "Invisible" sensors
  • Low installation and commissioning efforts

Used products

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