instrumentation & monitoring

Instrumentation > Instruments > Water > V-Notch Weir Monitor

V-Notch Weir Monitor

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

The V-Notch Weir System is used to measure water flow volume. It is used predominately in dams, open channels such as streams and in tunnels.

The system comprises a Stainless Steel plate with a notch profile chosen to suit predicted flow rates.

Flow of water over the weir head can be measured optically with a manual steel scale, or by using a Vibrating Wire transducer.

Readings can be taken manually with a Vibrating Wire readout or remotely by means of a data acquisition system.

Product Features
Uses proven Vibrating Wire technology
Suitable for manual or remote monitoring
Accurate and sensitive water level monitoring
Rectangular or triangular notched plate
Easy to automate via data acquisition software
Connecting cable is strong, screened and flexible
Product Benefits 
Low cost, low maintenance system
Simple principle of operation in manual version
Over 30 years of expertise in the design and manufacture of Vibrating Wire instrument technology
Accurate, repeatable readings over long cable lengths when using VW system
Long working life, long term stability and reliability
Ideal for long term monitoring of seepage in dams

The Vibrating Wire V-Notch Weir system has three notch options to suit different water flows and a choice of using manual or remote monitoring.

Manual reading has two options:

Manual reading of the optical readout by eye
Manual reading of the VW transducer using a VW readout

When using remote reading, the Vibrating Wire transducer is connected to a data acquisition system. Once the user has chosen which notch option is most suitable for a specific project, the weir plate is mounted at the exit of an approach channel or stilling basin through which the flow to be measured is channelled.

The measuring point for the head of water is located upstream of the weir plate and comprises either an optical Stainless Steel scale fixed to the basin wall for manual readings by eye, or a Vibrating Wire transducer suspended in the head of water.


The Vibrating Wire V-Notch Weir system uses the principle of gravitational discharge of water over a triangular or rectangular notched weir plate.

Typical applications include:
Longterm monitoring of dams
Drainage systems in dams and tunnels
Springs and artesian wells