The mechanisms of cross-shore sediment transport are listed below and 

 are more precisely documented in the literature by numerous authors as 

 best summarized in part by Boyd (1981), Nummedal and Snedden (1987), 

 Wright (1987), and Pilkey et al. (1993): 



a. Waves and wave-driven currents, including: 



(1) Powerful wave-orbital motions (Harms, Southard, and Walker 

 1982; Walker, Duke and Leckie 1983; Duke 1985; Duke 1987; 

 Duke 1990) and resulting orbital asymmetry (Gilbert 1889; 

 Wells 1967; Nielsen 1979; Hallermeier 1981a; Trowbridge and 

 Madsen 1984; Swift and Niedorada 1985; Dean and Perlin 1986). 



(2) Wave-induced upwelling and downwelling currents resulting 

 from onshore/offshore movement of surface water and return 

 bottom flows (Morton 1981, Snedden 1985, Wright et al. 1991). 



(3) Wave-induced rip currents (Bowen and Inman 1969; Cook and 

 Gorsline 1972; Reimnitz et al. 1976; Seymour 1983; Field and 

 Roy 1984; Wright and Short 1984; Cowell 1986; and Wright et 

 al. 1986). 



(4) Sediment diffusion arising from gradients in wave energy 

 dissipation associated with incoming incident waves (Wright et 

 al. 1991). 



(5) Sediment advection caused by wave orbital asymmetries 

 associated with incoming incident waves (Wright et al. 1991). 



(6) Long-period oscillations, which may be a more important process 

 for cross-shore sediment transport in higher energy wave 

 environments (Wright et al. 1991). 



(7) Interactions between groupy incident waves (alternating high and 

 low waves and forced long waves) (Shi and Larsen 1984, Dean 

 and Perlin 1986, Wright et al. 1991). 



(8) Groupy long waves (a forced long wave of infragravity 

 frequency resulting in alternating high and low waves) (Shi and 

 Larsen 1984, Dean and Perlin 1986, Wright 1987). 



b. Wind- and tide-driven currents including: 



(1) Semidiurnal and diurnal tidal currents (May 1979, Wright 1981). 



(2) Strong, unidirectional currents from wind forcing (Morton 1981). 



20 



Chapter 3 Evidence of Cross-Shore Sediment Transport 



