Seasonal particle responses to near-bed shear stress in a shallow, wave- and current-driven environment

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 over seasonal scales and (2) characteristic shear stress, τ_char, at which the rate of change to particle characteristics was most pronounced. Near-bed forcing and particle responses varied by season. Results indicated that moderate τ_char values of 0.125 Pa drove changes in particle composition during summer. In winter, particle concentration effects were most affected at τ_char 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 τ_char of 0.25 Pa. These results suggest that it may be more important to parameterize τ_char, as opposed to critical shear stress for erosion, for sediment transport models.