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, tau(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 tau(char) values of 0.125 Pa drove changes in particle composition during summer. In winter, particle concentration effects were most affected at tau(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 tau(char) of 0.25 Pa. These results suggest that it may be more important to parameterize tau(char), as opposed to critical shear stress for erosion, for sediment transport models.