Field verification of bed-mounted ADV meters

The accuracy of continuous-signal acoustic Doppler velocity (ADV) meters for gauging stream flows is examined, using a case study of nine bed-mounted ?Starflow? meters currently installed at a range of sites in the Pontbren catchment, Wales. The accuracy of the ADV meters was tested, under a range of velocities and depths, by comparing flow estimates with those based on a standard method of measurement with an impeller meter. The accuracy of the ADV meters was found to be poor for very low flows. For higher flows, in five concrete-lined sections, accuracy was reasonable without calibration of the ADV meter (estimates were within 20% of the current-metered flow for 68% of samples) and accuracy was good after calibration (estimates were within 20% of the current-metered flow for 93% of samples). In one natural channel, the performance after calibration was similarly good, while performance was fair to poor for two other natural channels. The predictability of the calibration results, and the reasons for the poor performance, are discussed.