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Suspended sediment concentration and the ripple–dune transition
Author(s) -
Schindler Robert J.,
Robert André
Publication year - 2004
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.1505
Subject(s) - flume , ripple , turbulence , sediment , acoustic doppler velocimetry , geology , shear stress , bedform , shear velocity , amplitude , soil science , geomorphology , hydrology (agriculture) , flow velocity , flow (mathematics) , intensity (physics) , critical resolved shear stress , sediment transport , geotechnical engineering , mechanics , physics , laser doppler velocimetry , shear rate , optics , thermodynamics , medicine , power (physics) , blood flow , viscosity
Abstract Flume experiments were conducted in order to monitor changes in flow turbulence intensity and suspended sediment concentration at seven stages across the ripple–dune transition and at three different positions above the bed surface. Three‐dimensional velocity measurements were obtained using an acoustic Doppler velocimeter (ADV). Suspended sediment concentration (SSC) was monitored indirectly using ADV signal amplitude. Although limited to time‐averaged parameters, the analysis reveals that SSC varies significantly with stage across the transition and with sampling height. The statistical analysis also reveals an apparent uniformity of suspended sediment concentration with height above the bed in the lower half of the flow depth at the critical stage in the transition from ripples to dunes. This is also the stage at which turbulence intensity is maximized. Statistically significant correlations were also observed between suspended sediment concentrations and root‐mean‐square values of vertical velocity fluctuations. These correlations reflect the various levels of shear‐layer activity and the distinct turbulent flow regions across the transition. Conversely, time‐averaged values of Reynolds shear stress exhibit a very weak relationship with suspended sediment concentrations. Copyright © 2004 John Wiley & Sons, Ltd.