mine the longshore sand transport rate and resultant shoreline evolution. 

 These were set to K x -> 0.5 and K 2 = 0.1 after initial testing (See, for 

 example, Kraus (1983), or Hanson (1987, 1989) for further discussion of these 

 parameters . ) 



In the present case, a wave transmission coefficient was assigned to each 

 of the six breakwaters as part of the calibration procedure. Initial trial 

 estimates of K T were made on the basis of information provided by Nakashima 

 et al . (1987). In order from east to west, the initial assigned values were: 

 0.9, 0.3, 0.5, 0.3, 0.7, 0.1. During the calibration, these were modified to 

 be: 0.4, 0.8, 0.2, 0.1, 0.0, 0.0. Modification of the original values was 

 expected since they were inferred from visual observation of wave and dye 

 movement, whereas the transmission coefficients in the model pertain to wave 

 heights and directions (wave energy fluxes) associated with combined wave 

 diffraction and transmission. 



The result of the preliminary calibration is shown in Fig. 9. The 

 measured shoreline of 1/23/86 was used as the initial shoreline in the model. 

 (It is interesting to note that this survey was made shortly after project 

 construction and that salients had already begun to form.) Overall, the 

 calculated shoreline position agrees well with the measured position of 

 7/29/87, demonstrating the importance of incorporating wave transmission at 

 breakwaters in shoreline simulations. The locations of the tips of salients 

 and their widths are well reproduced, whereas the calculated indentations in 

 the shoreline between the salients are somewhat less pronounced than were 

 produced in nature . 



Epilogue on field monitoring and model predictions . The quarterly profile 

 survey data of 12/88 indicate that the greatest beach development is in the 

 form of an intertidal tombolo at the breakwater having the least wave trans- 

 mission (western unit) . The salient at the breakwater next to this one has 

 undergone persistent accumulation, with the apex of the salient terminating 10 

 m from the breakwater. However, all but 20 m of this salient is subaqueous. 

 The salient at the third breakwater from the west differs from the others in 

 that sediment has been restricted to a beach without formation of a small- 

 scale subaqueous tombolo. The quantity of sediments deposited to the lee of 



55 



