Model Tests 



After calibrating and verifying the shoreline change model, eight 

 conceptual design alternatives were modeled, and several simulation variations 

 were performed for each of the alternatives. The intent of the simulations 

 was to quantify the shoreline impacts of the proposed Bolsa Chica navigable 

 ocean entrance system. In the simulation of Alternatives 1 and 3, no sand 

 management activities were specified; in other words, there were no inputs of 

 beach nourishment material along the modeled reach. In the simulation of 

 Alternatives 2, 4, 5, 6, and 8, renourishment of the Surf side-Sunset feeder 

 beach was specified at 1 million cu yd every 5 years. In the simulation of 

 Alternatives 7 and 8, impact mitigation sand management techniques were 

 modeled. A summary of the eight design alternatives evaluated is given in 

 Table 4. 



Table 4 

 Summary of Modeled Design Alternatives (Comprehensive Study) 1 



Design Alternative No. Entrance Channel Surf side -Sunset Impact Mitigation 

 & Simulation Code Location and Width Feeder Beach Sand Management 



1 WP1A,WP1B,WP1C Without Project 



2 WP2A,WP2B,WP2C Without Project 



3 PR01A,PR01B,PR01C Proposed Site, 800 ft 



4 PR02A,PR02B,PR02C Proposed Site, 800 ft 



5 PUC2A,PUC2B,PUC2C Warner Avenue, 800 ft 



6 PDC2A,PDC2B,PDC2C South of Site, 800 ft 



7 SM1A,SM1B,SM1C Proposed Site, 800 ft 



8 SM2A,SM2B,SM2C Proposed Site, 800 ft 



1) Design Alternatives 1 through 8 were simulated three times to investigate 

 the effect of potential variabilities in the incident wave climate as follows: 



a. Alternating available southern swell wave conditions (years 1 and 2). 



b. Low-intensity southern swell wave conditions (year 1). 



c. High- intensity southern swell wave conditions (year 2). 



As in the preliminary study, the 1983 surveyed shoreline position was 

 used as the initial shoreline. All model tests were performed for 5- and 10- 

 year simulation (prediction) periods using the same randomly selected 10-year 

 time history of northern hemisphere sea and swell wave conditions. The 

 southern hemisphere swell component of the incident wave climate was varied 



77 



No 



No 



Yes 



No 



No 



No 



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No 



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Yes 



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No 



Yes 



Yes 



Yes 



