Ice Profiler
Wave Profiler
Water Column Profiler
IRIS- Imagenex Datalogger
ASFM - Open Channel
Acoustic Scintillation Flow Meter
Bottom Frames
WERA HF Radar
Shallow Water Ice Profiler

Key Projects

Features and Applications

• The ASFM measures spatially averaged channel flow without placing any instrumentation in the channel proper.
• Placement of the transducers at the channel sides facilitates provision of real-time data.
• The ASFM does not require a diagonal signal path, nor is it biased by large scale eddies.
• Well suited to measurement of flows in heavily traveled channels. These include:
  • Harbor entrances
  • Navigable rivers
• Any location where floating debris, fishing or other hazards make mooring instruments in the channel proper impractical.

Description

Our instruments are mounted on a frame or bridge abutment on either side of the channel. Sound from a transmitter is detected by receivers on the opposite side. The turbulence produced by the current flowing in the channel causes the signals to vary with time, or scintillate. A pair of closely spaced transducers are placed at each side of the channel.

Each receiver detects the same pattern of signal fluctuations but those at the downstream receiver are delayed by the time required for the current to carry the turbulent eddies between the two paths. This time delay, combined with the known path spacing, allows the current speed to be calculated.

Current Projects

An ASFM system has been successfully operating in the Fraser River, on the British Columbia coast, since 1991. The most recent ASFM system is in operation at the Second Narrows in the Port of Vancouver. Currents and water levels are being measured at a railway lift bridge in the Narrows and telemetered to the Port management and traffic control centre for real time display.

The data will permit more efficient use of the Harbor through greater ship loadings and longer transit periods through the Narrows, as well as improving the flow of rail traffic over the bridge.