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the second station is on the upstream. The distance between the two station
(test length) is between 50m to 75m for the large channels. For lined small
channels this length may be kept at 15m to 20m. A third station is
maintained upstream about 15m to 20m away from the 2nd station to observe
the float for the steady flow of the float. Strong wind velocity and turbulence in
the stream should be avoided. Surface velocity thus obtained is multiplied by an
appropriate co-efficient, varying from 0.80 to 0.75 to obtain the mean velocity.
Current meter
Current meter is the best method to measure the velocity of stream flow
or canal flow. There are various types of current meters and may be classified
into :
i)
Conical cup type current meters such as Price Current meter.
ii)
Hellicoidal vanes type current-meter such as Haskell Current Meter
and Amsler Current Meter.
Conical type of current meter such as Price Current meter is most
popular and widely used.
Price's Current Meter
Fig. 3.2 : Price's current meter
(After Garg, 1998)
