16 



4 Analyses of Coastal 

 Processes and 

 Geomorphology 



This first part of this chapter consists of three sections describing: the 

 alongshore sediment transport calculations; updated cross-shore sediment trans- 

 port calculations (i.e., subsequent to those presented in Parson, Morang, and 

 Nairn (1996)); and the results of quasi-3-D sediment transport modeling. 



Sediment transport calculations were completed with COSMOS, which is a 

 deterministic numerical model for the simulation of coastal processes. Each of 

 the processes is evaluated at approximately 250 finite difference calculation 

 points across the profile. The various individual predictive phases of COS- 

 MOS, as well as the integrated model, have been extensively tested against 

 both laboratory and field data (see Southgate and Nairn (1993), and Nairn and 

 Southgate (1993)). The model is described in more detail in Parson, Morang, 

 and Nairn (1996). 



The remainder of the chapter describes an investigation of the geomorphol- 

 ogy of the study area through a review of nearshore profile evolution. 



Results of the Alongshore Sediment Transport 

 Calculations 



Single grain size across the profile 



This section describes the results of the average annual alongshore sediment 

 transport calculations that were made for each profile line using grain sizes of 

 0.2 mm, 0.4 mm, and 2 mm with the original version of C0SM0S-2D. Pro- 

 file line locations are shown in Figure 3. 



Input for the calculation of average annual alongshore transport consists of 

 a list of representative wave conditions (wave height, period, and direction) 

 and durations (i.e., number of hours per year for each condition). This list was 

 derived from the percent occurrence tables of height and period by direction 



Chapter 4 Analyses of Coastal Processes and Geomorphology 



