SEDIMENT-WAVE PARAMETRIC CHARACTERIZATION OF BEACHES

Sediment-wave parameters, notably the parameter Omega = H-b/WsT (where H-b is wave breaker height, W-s sediment fall velocity, and T wave pe riod), have been used in the literature to identify thresholds between various beach morphodynamic states ranging from reflective, through i ntermediate, to dissipative. Such parameters may be useful as elementa ry descriptors of beaches, especially in microtidal swell wave setting s with mature sediment suites, and when used in conjunction with conce ptual beach state models elaborated in recent years. Although the prob lems of temporal wave height variability and large tide ranges have be en addressed in the parametric characterization of various beach types , these factors, together with sediment variability, may result in bea ch morphodynamic systems that cannot be meaningfully characterized by sediment wave parameters. Morphodynamic parameters such as the Iribarr en Number xi(b)(xi(b)=tan(b)/(HbL0)(0.5), where tan(b) represents beac h slope, H-b is wave breaker height, and L-o deepwater wavelength), an d the surf-scaling parameter epsilon (epsilon = a(b)w(2)/(gtan(2)b), w here a(b) is runup amplitude on the beach. w wave radian frequency, an d g the gravitational constant), are based on beach slope, and avoid t he problem of the choice of representative beach sediment parameters. The intertidal beach slope is also a better index of characterization of spatial and temporal changes in the reflective-to-dissipative beach morphodynamic continuum, especially in settings with large tide range s.