The Effect of Stratification on the Residual Flow in a Mixed-Energy Tide-Dominated Inlet

Analysis of thirteen-hour ADCP observations of flow revealed complex residual flow patterns in the inlet gorge and main ebb-delta channel of Texel Inlet (the Netherlands). Main features are the dominance of axial residual flow velocities over the transverse velocities, and a typical density-driven distribution of ebb-dominant flow in the top-layers and flood-dominant flow in the near-bed regions. Numerical simulations were made using the process-based model Delft3d Online Morphology. The model is capable of reproducing the dominant features of the residual flow patterns accurately when fresh-water discharge in the basin is included. Analysis of the model results shows that density differences are essential to create the tilt of the residual flow distribution from horizontal to the observed vertical shear. The resulting more pronounced segregation of ebb and flood flow results in augmented residual ebb-velocities along the Texel coastline and Noorderhaaks, and residual flood velocities along the North-Holland coast.