Reflective beach

From Coastal Wiki
Jump to: navigation, search
Definition of Reflective beach:
Beach where waves dissipate their energy (wave breaking) close to the shoreline.
This is the common definition for Reflective beach, other definitions can be discussed in the article

Notes

Usual characteristics of reflective beaches are:

  • Steep beach slope
  • Coarse sediment
  • Long-period waves (swell)
  • Small tidal amplitude

The so-called Dean parameter [math]\Omega[/math] [1][2] is often used as a measure of the degree of beach reflectivity. It is defined as

[math]\Omega = \Large \frac{H_s}{wT_p} \normalsize , \qquad(3)[/math]

where [math]H_s[/math] is the offshore significant wave height before breaking, [math]T_p[/math] is the peak spectral wave period and [math]w[/math] is the mean sediment fall velocity. According to Wright and Short (1984) [3] reflective beaches correspond to [math]\Omega \lt 1 [/math].

See for more details: Shoreface profile.

References

  1. Gourlay, M. R. 1968. Beach and dune erosion tests. Rep. m935/m936, Delft Hydraul. Lab., Delft
  2. Dean, R.G. 1973. Heuristic models of sand transport in the surf zone. Proc. Conf. Eng. Dynamics in the Surf Zone, Sydney: 208-214
  3. Wright, L.D. and Short, A.D. 1984. Morphodynamic variability of surf zones and beaches: a synthesis. Mar.Geol. 56: 93-118