suspended load in the surf zone was emphasized by Dean (1973) and verified 

 through measurements under prototype-scale laboratory conditions by Dette 

 (1986) and under field conditions by Kraus and Dean (1987) among others. 



152. Although profile change is highly stochastic on a microscale 

 involving turbulence, movement of individual and collective grains, and 

 various types of organized flows, if viewed on a macroscale, changes in the 

 profile are surprisingly regular and consistent with respect to large features 

 such as bars and berms . Several landmark studies, such as Keulegan (1945), 

 Shepard (1950), Hands (1976), and Sunamura (in press) have characterized the 

 geometry of morphologic features of beach profiles in the field. The 

 possibility of successfully describing morphologic features under complex wave 

 and water level conditions, as indicated by the above studies, formed much of 

 the early foundation of the present study in the development of a numerical 

 model of beach profile change . 



153. It was shown by Sonu (1969), Short (1979), Sasaki (1983), Wright 

 and Short (1984), and Sunamura (in press) that even very complex three- 

 dimensional beach changes may be described by a small number of schematized 

 beach states characterized by different values of one or two nondimensional 

 parameters. Consequently, if the main processes of beach profile change are 

 identified, response of the profile to wave and water level variations may be 

 predicted based on semi -empirical relationships developed from relevant data. 



154. Several criteria for delineating bar and berm profile response 

 expressed in terms of wave and sediment properties have been proposed. The 

 first criterion involved only wave steepness (Waters 1939, Scott 1954), 

 whereas later-developed criteria included nondimensional quantities character- 

 izing the beach sediment (Kemp 1961; Iwagaki and Noda 1963; Nayak 1970; Dean 

 1973; Sunamura and Horikawa 1975; Rushu and Liang 1986; Kriebel , Dally, and 

 Dean 1987). The formation of bar and berm profiles is closely related to the 

 direction of cross-shore transport. Criteria similar to those used to 

 distinguish between bar and berm formation have been applied to determine 

 transport direction (Rector 1954, Hattori and Kawamata 1979). 



155. The existence of an equilibrium profile, a profile of constant 

 shape which is approached if exposed to fixed wave and water level conditions, 

 was proven to be a valid concept under laboratory conditions by Waters (1939), 



41 



