Measurement Devices

A. Weirs:

• It is used to measure the flow in an irrigation channel or the discharge of a well or a canal outlet at the source.
• It is a notch of regular form through which the irrigation stream is made to flow.

B. Barrage:

• The function of barrage is similar to that of weirs but the heading up of water is affected by the gates alone.
• The crust level is kept at the low level.
• During the flood, the gates are raised to clear off the high flood level.

C. Flumes

• Semi-circular, rectangular and trapezoidal.
• Flumes are specially shaped, engineered structures used to measure the flow of water in open channels.
• The floor of upstream section is level and the wall coverage towards throat section.
• The wall of the throat section is parallel and the floor is inclined downward.
• Discharge through the flume can occur under either free flow or submerged flow condition.

D. Orifice:

• An orifice plate is a device used for measuring flow rate, for reducing pressure or for restricting flow.
• It maybe two types . i.e. Free flow and Submerged.