Acoustic Measurement of River Discharge

Abstract

This paper presents a new moving‐boat method for rapidly measuring river discharge using an acoustic Doppler current profiler (ADCP). The method uses an ADCP to measure current profiles and boat velocity along transects across a river. Measurements from the River Elbe, near Hamburg, Germany, are presented to illustrate the method and its associated uncertainties. An ADCP measures profiles of current velocity relative to the boat and the velocity of the boat relative to the bottom; the discharge calculation depends only on these data, and it is not necessary to know either compass heading or the actual location of the boat. Furthermore, the transect can be an arbitrary curve as long as it starts near one side of the river and ends near the other. Uncertainty in discharge from random errors, biases, and missed data near the surface, bottom, and sides of the river is investigated. Missed data near the surface and bottom are the largest source of error unless the data are corrected by assuming model profiles....