(1968) and Dean (1973). Furthermore, in the process of quantifying morpho- 

 logic features as described below, the dimensionless fall speed emerged in 

 many of the developed empirical relationships. In most cases, the value of 

 the dimensionless fall speed varies over the same order of magnitude for a 

 wide range of sand and wave conditions, making it more appealing to use than, 

 for instance, the parameter H^/D . Thus, it is concluded that the parameters 

 Hq/Lq and H^/wT are the most basic and general for prediction of cross - 

 shore beach change caused directly by large incident breaking waves. (Some 

 researchers use the breaking wave height instead of the deepwater wave height 

 in beach morphology descriptors, but this requires application of a breaking 

 wave criterion to be useful in a predictive mode.) 



220. The dimensionless parameters Hq/Lq and H^/wT have distinct 

 physical meanings. The wave steepness H^/Lq is a measure of the wave 

 asynunetry, which influences the direction of fluid flow in the water column. 

 The dimensionless fall speed H^/wT is a measure of the time that a sediment 

 grain remains suspended in the water column (Dean 1973). Also, the wave 

 height entering in the dimensionless fall speed directly introduces the 

 magnitude of the wave height into the description of sediment motion (which is 

 lacking in the wave steepness, as demonstrated by Saville 1957). The same 

 argument is suggested for the wave period. Thus, although mathematically one 

 power of Hq could be cancelled in the numerators of both sides of Equation 2 

 (and, similarly, for T in the denominators, since L^ -v T^) , physically, the 

 variables H and T enter on both sides of the equation for different 

 reasons, on the left side for the wave asymmetry and the right side for the 

 magnitudes of the wave height and wave period. 



Irregular (field) waves 



221. The criteria investigated above were developed for predicting 

 tendencies for bars or berms to form (or for the profile to erode or accrete) 

 under idealized laboratory conditions of regular waves and constant water 

 levels in small and large wave tanks. The utility of such criteria has been 

 questioned for applicability to the field situation (Seymour and King 1982, 

 Seymour and Castel 1988). In the field, waves have a spread in height and 

 period, implying potential differences in cross -shore sand transport produced 

 directly by regular and irregular waves. Irregular waves may also be accom- 



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