placed beach fill material. The model was then applied to a five-year 

 simulation. Results were good, showing correct trends of shoreline recession 

 on the west side, advancement on the east side, salient type, and a pivot point 

 in the shoreline where the position did not vary over time. 



Summary. Table 7 summarizes the GENESIS modeling parameters for 

 the detached breakwater projects discussed above and presented in 

 Appendix A. The best modeling parameters to use for shoreline change 

 modeling studies are those that recreate known shoreline change through the 

 calibration and verification process. However, calibration and verification 

 data sets are not always available, and parameters must be estimated based on 

 previous studies. Selected input data are briefly reviewed below. 



Table 7 



GENESIS Modeling Parameters for Detached Breakwater Studies 



Project Name 



Number of 

 Breakwater 

 Segments 



Transmission 

 Coefficients 



Transport 

 Parameter 

 «1 



Transport 

 Parameter 

 K 2 



Time- 

 Step 

 (hour) 



Longshore 

 Grid 

 Spacing 

 (m) 



Median 

 Grain 

 Size 

 (mm) 



Holly Beach, 



Louisiana 



(Hanson, 



Kraus, and 



Nakashima 



(1989) 



6 



0.0, 0.0, 

 0.1, 0.2, 

 0.8, 0.4 

 (west to 

 east) 



0.50 



0.10 



0.25 



4.6 



0.20 



Lakeview 

 Park, Lorain, 

 Ohio (Hanson 

 and Kraus 

 1989b, 1991J 



3 



0.50, 0.22, 

 0.30 (west 

 to east) 



0.42 



0.12 



0.30 



7.6 



0.40 



Presque Isle, 



Pennsylvania 



(USAED, 



Buffalo, 



unpublished) 



3 (Bch 10) 

 3 (Bch 1 ) 



0.25 (all) 

 0.50 (all) 



0.40 



0.10 



0.12 

 0.12 



3 

 3 



7.6 

 7.6 



1.0 

 1.0 



Bay Ridge, 

 Maryland 

 (Appendix B) 



11 



0.10 



0.50 



0.25 



1 



3.8 



0.5 



62 



(1) Structure transmission. In Version 2.0 of GENESIS, a constant wave 

 transmission value is assigned to each breakwater segment. In nature, 

 transmission for a given structure varies as a function of the incident wave 

 characteristics and water levels. For GENESIS simulations of Lakeview Park 

 and Holly Beach, the breakwater transmission coefficients were determined 

 through the calibration process to reproduce known shoreline change. For 

 Presque Isle, breakwater transmission coefficients were ultimately chosen 

 based on physical model testing results. The availability of transmission data 

 from the physical model tests in the Presque Isle study provided an 

 opportunity to compare an average K T with a transmission coefficient 

 calculation using a standard calculation procedure. This comparison indicated 



Chapter 3 Tools for Prediction of Morphologic Response 



