The Vibrating Wire V-Notch Weir System comprises of two elements: V-Notch weir and Vibrating Wire Weir Monitor.

The V-Notch (triangular) Weirs are typically installed in open channels such as streams to determine discharge (flow rate).

The main component is a cylindrical weight suspended from a vibrating wire force transducer. As the water level changes, the changing buoyancy force on the cylinder acts on the transducer. The output from the instrument can be used to calculate the flow rate when read in conjunction with a V-notch weir.

Products & Accessories

Vibrating Wire Weir Monitor

Some of the features of the VW Weir Monitor are:

  • Vibrating Wire precision water level sensor
  • Simple, low cost and robust instrument
  • Accurate and sensitive water level monitoring
  • High resolution monitoring
  • Low maintenance system
  • Variety of ranges: 150, 300, 500, 1500mm
  • Resolution*: 0.025% full scale (minimum)
Vibrating wire weir monitor

V-Notch Weir Plate

V-Notch Weir Plate specifications:

  • Made from corrosion resistant materials
  • Fixed or portable
  • Simple principle
  • Very low maintenance

Geomotion specialises in the automation of V-notch weirs, offering transducer and level radar flow meters. Contact us for a customised V-Notch Weir plate quote from 15 to 100 Litres/second.

V-notch weir plate

Automated Water Level Radar

The Automated Water Level Radar is a level and flow monitoring product for V-Notch flow. Suitable for run-dry installations.

Some of the features of the Automated Water Level Radar are:

  • Continuous Readings
  • Ingress Protection: IP66/68
  • Measuring Range: up to 8m
  • Temperature: -40 to 60°C
  • Accuracy: up to ± 5 mm
  • 4G Modem
  • 20W Solar Panel & Rechargeable battery combo


Discharge is a function of the geometry of the weir and the height of the water above the notch. The weir monitor reads the height of the water from which seepage or discharge rates can be calculated.

The system can be read remotely and automatically when used in conjunction with a data acquisition system. Manual reading can be done by reading the water level with a scale or a staff gauge, or by reading the monitor with a Vibrating Wire Readout.


The Vibrating Wire V-Notch Weir system is typically used as a part of dam safety monitoring program. They can also be used to measure flow rates in open streams, channels or tanks.

Typical applications include:

  • Longterm seepage monitoring of dams and tunnels
  • Drainage systems in dams and tunnels
  • Springs and artesian wells
  • Stilling basin monitoring
  • Environmental monitoring

Geomotion offer installation and monitoring services to support this system. For more information please email or contact any of our locations.