Acoustic Doppler current profiler (ADCP) to measure streamflow.
The acoustic Doppler current profiler (ADCP), originally developed for oceanographic work, was adapted for inland streamflow measurements. This instrument is transforming the USGS streamgaging program.
Here, the Acoustic Doppler current profiler, mounted on side of inflatable raft, is connected to an onboard computer to measure streamflow. The ADCP transmits an acoustic pulse through the water column. A “Doppler shift” is measured as the signal is reflected off of particles in the water, such as sediment and microorganisms. Based on the assumption that the particles in the water are traveling at the same velocity as the water itself, a water velocity is computed.
You can download a PDF file describing the use of the ADCP in USGS: USGS Fact Sheet 2008-3001.