APPENDIX A 



DISCUSSION OF CONSTANTS AND SOME OF THE VARIABLES 

 REQUIRED BY THE MODEL 



Establishing the grid-contour system requires several variables. IMAX 

 represents the number of cross-shore grid lines desired and JMAX the number 

 of contours simulated. DX represents the spacing between the IMAX grid lines 

 and DY the spacing between the contours. DX is a value which must be chosen 

 along with IMAX and JMAX such that sufficient detail is obtained where 

 necessary (e.g., in the shadow zone, if diffraction effects are believed to 

 be ^ery important, DX must be assigned a sufficiently small value so that at 

 least some points lie within the shadow zone for the larger wave angles). DY 

 is not a constant, but a dimensional array which is computed by the model 

 according to the contour location. Once the depths of contours to be modeled 

 are chosen, the initialization of DY and the y values are computed with the 

 following equation after Dean, 1977 



h = A y2/3 (A-1) 



where h is the depth, y is the offshore distance and A is the scaling parameter 

 Dean gives values for A for several diameter sediments; however, if long-term 

 beach profiles are available for the site being modeled, the modeler may want 

 to choose a slightly different A value to more closely match the site-specific 

 beach profile. Figure A-1 presents values of A versus diameter (after Moore, 

 1982). The model is programmed to input the h(I,J) values (depths as shown in 

 Figure 1, called DEEP (I, J) in the program) read in the value of A (called 

 ADEAN in program) and it then computes the y values. Also shown in Figure 1 

 is the height of the berm (BERM) and this value, along with the beach-face 

 slope (SFACE), is required as program input and can be obtained from beach 

 profile site data. Because the model does not include water level 

 fluctuations such as tides, all values are to be referenced to a chosen 

 datum. Other geometrical constants depending on the site include SJETTY (the 

 length of the jetty), MMAX (the number of structures to be input), and IJET 

 (M), M = 1,2, ...MMAX (the smaller I value adjacent to the M^h structure's 

 location). If no structure is required, as in a beach fill, the value of 

 SJETTY must be entered as 0.0, with MMAX and IJET (M) entered as 1 and 

 (IMAX/2), respectively. As set up presently, the groin locations must be 

 equally spaced. 



One constant used throughout the program is the breaking wave criteria 

 (CAPPA in the program) equal to 0.78. It is required in several different 

 computations and always governs the maximum wave height allowed according to 

 the depth. 



Another group of variables assigned values within the program is the 

 sediment and fluid properties. These include fluid mass density, sediment 

 mass density, porosity, and the angle of repose (e.g., RHO = 1.99, RHOS = 

 5.14, POROS = 0.40, and REPOSE = 32°, respectively). The values can easily be 

 changed to reflect site conditions. 



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