Averaged indicators of secondary flow in repeated acoustic Doppler current profiler crossings of bends
Article first published online: 3 SEP 2005
Copyright 2005 by the American Geophysical Union.
Water Resources Research
Volume 41, Issue 9, September 2005
How to Cite
2005), Averaged indicators of secondary flow in repeated acoustic Doppler current profiler crossings of bends, Water Resour. Res., 41, W09405, doi:10.1029/2005WR004050., and (
- Issue published online: 3 SEP 2005
- Article first published online: 3 SEP 2005
- Manuscript Accepted: 27 MAY 2005
- Manuscript Revised: 11 MAY 2005
- Manuscript Received: 21 FEB 2005
- backscatter intensity;
- secondary flow
 Cross-stream velocity was measured in a large river bend at high spatial resolution over three separate survey episodes. A suite of methods for resolving cross-stream velocity distributions was tested on data collected using acoustic Doppler current profilers (ADCP) in the sand-bedded Sacramento River, California. The bend was surveyed with repeated ADCP crossings at eight cross sections during a rising limb of high discharge in February 2004 and twice on recession in March 2004. By translating and interpolating repeated ADCP crossings to planar grids, velocity ensembles at similar positions along irregular boat paths could be averaged. The averaging minimized turbulent fluctuations in streamwise velocities over 1 m/s, enabling the resolution of weaker cross-stream velocities (~15-30 cm/s). Secondary-flow influence on suspended sediment was inferred from a lateral region of acoustic backscatter intensity aligned with outward flow over the point bar. A near-bed decrease in backscatter intensity across the pool corresponded with inward cross-stream flow. These suspension indicators were used to orient averaged velocity grids for unambiguously defining the cross-stream velocity magnitudes. Additional field investigations could test whether the correlation between cross-stream velocity and backscatter intensity patterns results from helical recirculation of suspended sediment to the inside of the bend. These river measurements, consistent with classic and recent laboratory studies, show that ADCP surveys can provide refined views of secondary flow and sediment movement in large rivers.