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Flow over bedforms in a large sand-bed river: A field investigation

April 3, 2008

An experimental field study of flows over bedforms was conducted on the Missouri River near St. Charles, Missouri. Detailed velocity data were collected under two different flow conditions along bedforms in this sand-bed river. The large river-scale data reflect flow characteristics similar to those of laboratory-scale flows, with flow separation occurring downstream of the bedform crest and flow reattachment on the stoss side of the next downstream bedform. Wave-like responses of the flow to the bedforms were detected, with the velocity decreasing throughout the flow depth over bedform troughs, and the velocity increasing over bedform crests. Local and spatially averaged velocity distributions were logarithmic for both datasets. The reach-wise spatially averaged vertical-velocity profile from the standard velocity-defect model was evaluated. The vertically averaged mean flow velocities for the velocity-defect model were within 5% of the measured values and estimated spatially averaged point velocities were within 10% for the upper 90% of the flow depth. The velocity-defect model, neglecting the wake function, was evaluated and found to estimate thevertically averaged mean velocity within 1% of the measured values.  

Publication Year 2008
Title Flow over bedforms in a large sand-bed river: A field investigation
DOI 10.3826/jhr.2008.3040
Authors Robert R. Holmes, Marcelo H. Garcia
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Hydraulic Research
Index ID 70194115
Record Source USGS Publications Warehouse
USGS Organization Office of Surface Water