Antonius Laenen 1983 <p><span>Acoustic velocity metering systems used to measure the water velocity along a diagonal path across a stream can also be used to measure stage and streambed changes. Underwater acoustic transmissions reflected from the water surface can accurately measure depth above transducers. Similarly, signals reflected from the streambed can indicate streambed changes in the vicinity midway between transducers.</span></p> application/pdf 10.1029/WR019i005p01317 en American Geophysical Union Measuring water surface and streambed elevation changes with the acoustic velocity metering system article