(a) Wave characteristics; 



Evaluation point (usually the breaker line) 



Regular or irregular forms 



Height 



Direction (number of incident wave trains) 



Period 



Type of breaker (spilling, plunging, or surging) 



Wave energy transfer to other scales (nonlinear effects) 



Soliton formation (harmonic scales) 



Subharmonics (longer period scales) 

 Breaker location 



Presence of edge waves or infragravity waves 

 Wave-current interactions 

 Surf zone wave energy decay 



(b) Wind characteristics : 



Strength 



Direction 



Duration 



Atmospheric pressure gradients 



(c) Tidal influence 



Mean water depths 

 Width of surf zone 



(d) Planform and bathymetry 



Coastal boundaries (natural headlands, jetties, breakwaters) 



Coastal planform 



Offshore bathymetry (refraction, diffraction) 



Local bathymetry (bars, troughs) 



Nearshore profile 



Beach face slope 



Reflections 

 Bottom roughness (smooth, ripples, dunes) 



(e) Fluid 



Gravity (density, saltwater, freshwater) 

 Temperature (viscosity) 

 Surface tension (air entrainment) 



Turbulence intensities (wave breaking, bottom shear, 

 sediment effects) 



(f) Sediment 



Size, gradation, shape, unit weight 



Porosity, permeability 

 Current variations in space and time result from the interplay of many of these 

 features plus the fact that most are unsteady in nature. Many simplifications 

 and assumptions are necessary to evolve theories from all these factors. 



63 



