Particle Responses to Near-Bed Shear Stress in a Shallow, Wave- and
Current-Driven Environment
Abstract
Novel analysis of in-situ acoustic and optical data collected in a
shallow, wave- and current-driven environment enabled determination of:
(1) particle characteristics that were most affected by near-bed
physical forcing, and (2) characteristic shear stress,
τchar, at which the rate of changes to particle
characteristics were most pronounced. Results indicated that moderate
τchar values of 0.125 Pa drove changes in particle
composition during summer. In winter, particle concentration effects
were most affected at τchar of 0.05 Pa, suggesting
dominance of fluff layer resuspension. Changes to particle size were
most relevant during a biologically productive springtime period, with
initiation of particle disaggregation occurring most commonly at
τchar of 0.25 Pa. The values of τchar
determined from acoustic and optical data are consistent with
laboratory-based measurements of critical shear stress for resuspension
of site sediments, and with typical critical shear stress values for
resuspension of cohesive sediments as reported in the literature.