Observations of a Developing Boundary Layer in a Tidally Forced Estuary.

摘要

Field observations of sediment resuspension within a developing tidal boundary layer were collected during two field deployments from summer 2011 in a long straight channel of the Great Bay Estuary of New Hampshire. The first deployment observed boundary layer development during typical tidal forcing, while the second deployment monitored the tidal boundary layer development response to Tropical Storm Irene. During a typical flood tide, the flow field over the flat sandy mud bed at the monitoring location is unidirectional. Bed stress estimations suggest that during typical tidal forcing, the Estuary is in local morphological equilibrium, and the boundary layer supports an observable sublayer in the lowest 0.5 cm of the water column, where viscous effects dominate, suggesting that solute flux from the bed is controlled by molecular diffusion. Additional storm forcing generates bed shear stress that exceeds the threshold of sediment motion (0.15 N/m 2), suggesting that turbulence controls solute mixing.