Program (Brater et al. 1974, 1975, 1977; 

 Marks and Clinton 1974). This study is 

 limited primarily to physical effective- 

 ness of low cost groins and revetments. 

 In another study, historical records 

 were compared with the existing condi- 

 tions to discover changes in littoral 

 drift and the beach erosion after a jetty 

 was constructed (Dantin et al. 1974). 

 One series of biological studies was con- 

 ducted both prior to and after installa- 

 tion of various parts of a marina in 

 southern California (e.g., Reish 1961, 

 1962, 1963). 



Another research method involves 

 systematic studies conducted after the 

 installation of structures. These studies 

 primarily described the physical condi- 

 tions in the presence of a structure. 

 For instance, Diskin et al. (1970) de- 

 scribed piling up of water behind low 

 and submerged breakwaters, and Nagai 

 (1961) discussed the absorption of wave 

 energy by concrete facing components. 

 An exception to this generalization has 

 been a number of biological studies 

 which have compared the existing bulk- 

 headed areas to adjacent natural shore- 

 lines. Examples of this method of study 

 are found in Corliss and Trent (1971), 

 Ellifrit et al. (1972), Heiser and Finn 

 (1970), Millikan et al. (1974), Mock 

 (1966), Moore and Trent (1971), Trent 

 et al. (1976), and White (1975). 



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