Macro-Meso Tidal Beach Morphodynamics: An Overview


  • A.D. Short


Macro-tidal, meso-tidal, beaches, ridge and runnel, beach classification


Macro- and meso-tidal beaches are ubiquitous global coastal features about which comparatively little is known compared to their micro-tidal counterparts. A review of the literature reveals a considerable range in macro-tidal beach morphology and dynamics but with little perceived order in the range. This review together with recent morphological data from macrotidal beaches on the central Queensland coast are combined to provide an overview, and to identify three types of macro-tidal beaches. Two are true beaches. Higher waves, and particularly swell produces moderate gradient (1-3°), concave, planar beaches dominated by incident, though infragravity wave energy. Moderate waves and sea conditions tend to produce lower gradient (0.5°), multi-bar (ridge and runnel) topography also attributable to infragavity standing waves. As wave energy drops still further a third type results with a high tide beach fronting tide-dominated tidal flats. This latter is not a true beach but rather a transition from beach to tidal flat.