Continuous measurement of water velocity

[marck1]

I would like to measure a river's water velocity, is there a sensor that does this? I figure the sensor employs an acoustic Doppler principle to reliably measure flow velocity in a variety of naturally occurring conditions. Here is an example of a probe that does the same thing: http://www.hachhydromet.com/web/ott_hac ... ppler.html

[Franklin97355]

The one you linked to would do it.If you want something more low tech I'd use a paddle wheel and counter to read how many revolutions the wheel makes.

[spork99]

You could use a pair of pressure sensors and use Bernoulli's equation (PT - PS = ½ ρ V^2) to get the speed, that's how aircraft measure airspeed and I've seen probes for measuring water flow that operate on the same principle. I'd want to know more about your application before making a recommendation though. Are you looking to leave the sensor in place and monitor/log the flow over an extended time period or are you looking to measure a variety of spots in the river over a shorter period of time?