Tidal inlet morphology classification and empirical determination of seaward and down-drift extents of tidal inlets

摘要

The Hayes classification of tidal inlet geomorphic type and the distances from the inlet to the most seaward and down-drift extents of ebb deltas are examined. For this purpose, a database was compiled for 89 tidal inlets along the Atlantic Ocean, Gulf of Mexico, and Pacific Ocean coasts of the United States. The database contains spring or diurnal tidal prism and the average significant wave height and wave period from a 20-year hindcast. The Hayes diagram aims to classify inlet plan-view morphology by tide range and wave height. Based on the work presented here, it is concluded that the inlet classification of Hayes has limited applicability for describing the morphology of typical tidal inlets, and replacement of tide range by inlet tidal prism did not improve the classification. Best correlation for the two ebb delta extents was found for inlets segregated by wave exposure (as mild, moderate, or high) and by tidal prism. There was poor or no correlation for moderately wave-exposed inlets, and moderate to high correlation was found for mildly and highly exposed inlets. The seaward and down-drift extents of inlets tend to remain constant up to a tidal prism less than 10 ~8 m ~3, depending on wave exposure, and then increase linearly with tidal prism. It is postulated that a tidal prism less than approximately 10 ~8 m ~3 is a tipping point required to overcome other factors controlling tidal inlet plan-form morphology.