Home Archived April 24, 2019

  California Water Science Center

Velocity Observations

The graphs below show continuous velocity measurements made at the North Fork Toutle River in Washington state during 1989. Electromagnetic velocity meters were mounted on the same vertical-support pipe used for sonar. Voltage output from the meters was converted to digital form by sampling simultaneously with the sonar readings at 2 Hertz. Three positions, separated vertically by 0.34 m, were available on the meter frame for velocity measurements.

-- adapted from Dinehart, R.L., 1992, Evolution of coarse-gravel bedforms: Field measurements at flood stage, Water Resources Research, v. 28, n. 10, pp. 2667-2689.

Correlative velocity fluctuations

Correlative velocity fluctuations
Three meters show velocity fluctuations with short-term correlations in the upper half of flow. The fluctuations have a range of durations from a few seconds to over half a minute.

Velocity over a gravel bedform

Velocity over a gravel bedform
Velocity measured near mid-depth shows influence of gravel bedform on mean velocity.

Comparison of velocity over gravel bedforms

Comparison of velocity over gravel bedforms
Standard deviation of velocity near mid-depth decreased as flow receded.

Accessibility FOIA Privacy Policies and Notices

USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://ca.water.usgs.gov/user_projects/gravel/velocity.html
For Page Information: Send Us a Message
Page Last Modified: Wednesday, 05-Oct-2011 15:15:57 EDT