Effects of Horizontal Velocity Variations on Ultrasonic Velocity Measurements in Open Channels

Water-Resources Investigations Report 91-4200



Use of an ultrasonic velocity meter to determine discharge in open channels involves measuring the velocity in a line between transducers in the stream and relating that velocity to the average velocity in the stream. The standard method of calculating average velocity in the channel assumes that the velocity profile in the channel can be represented by the one-dimensional von Karman universal velocity profile. However, the velocity profile can be described by a two-dimensional equation that accounts for the horizontal velocity variations induced by the channel sides. An equation to calculate average velocity accounts for the two-dimensional variations in velocity within a stream. The use of this new equation to calculate average velocity was compared to the standard method in theoretical trapezoidal cross sections and in the L-31N and Snapper Creek Extension Canals near Miami, Florida. These comparisons indicate that the two-dimensional variations have the most significant effect in narrow, deep channels. Also, the two-dimensional effects may be significant in some field situations and need to be considered when determining average velocity and discharge with an ultrasonic velocity meter.

Suggested Citation

Effects of horizontal velocity variations on ultrasonic velocity measurements in open channels; 1992; WRI; 91-4200; Swain, E. D.

Publication type Report
Publication Subtype USGS Numbered Series
Title Effects of horizontal velocity variations on ultrasonic velocity measurements in open channels
Series title Water-Resources Investigations Report
Series number 91-4200
DOI 10.3133/wri914200
Year Published 1992
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Caribbean-Florida Water Science Center
Description v, 15 p.
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