The Use of Channel Characteristics for the Calibration of Index Velocity Ratings for Acoustic Doppler Velocity Meters

Acoustic Doppler Velocity Meters (ADVMs) have become popular for estimating discharge in rivers exhibiting complex flow characteristics. To use the ADVMs for estimating channel discharge, a relation needs to be developed between the mean channel velocity and the index velocity provided by the ADVM. In the past, this relation was primarily developed empirically. To improve the accuracy of ADVM discharge estimates, a more theoretical approach was developed for defining the relationship between a river’s mean channel velocity and the ADVM’s index velocity. This approach involves using the channel’s geometry at a single cross-section to more accurately define the mean channel velocity to index velocity relation by means of fewer discharge measurements. The use of the channel geometry allows for a more theoretical explanation of the mean-index velocity relation, whether linear or nonlinear, resulting in a more accurate extrapolation of the rating.