Keywords: Accretion, Currents, Downdrift beaches. Environmental concerns. 

 Hydraulic model (three-dimensional), Littoral transport. Numer- 

 ical model. Offshore island, Tombolo, Wave attenuation. Wave 

 diffraction. Wave refraction 



The location of large surface industrial zones along seashores 

 often competes with other coastal activities, such as recreational pur- 

 suits, fishing, nature reserves, etc. The construction of an artificial 

 island, near the shore, poses many problems particularly with its impact 

 on the environment. The results of a study examining this aspect include 

 (a) the influence of the island on local wave climate or swell, consequent 

 shoreline changes, tidal currents, and the resulting evolution of the 

 sandy seabed; and [b) the dispersion of industrial effluents. 



The effect of the island on swell and on shore stability and the 

 calculation of pollutant dispersion are approached by the use of mathe- 

 matical models; the effect of the island on tidal currents is analyzed 

 on a reduced-scale physical model. 



110. LEYPOLDT, H., "Shoreline Formation by Currents," Shove and Beadh^ 

 Vol. 9, No. 1, Jan. 1941, pp. 14-17, 29-31. Discussions by 



M.P. O'Brien, Apr. 1941, p. 46; O.F. Evans, Apr. 1941, pp. 46-47; 

 Closure, Apr. 1942, p. 21. 



Keywords: Accretion, California (Santa Monica), Crenulate-shaped bay, 

 Currents, Downdrift beaches. Littoral transport, Shipwrecks, 

 Tombolo 



Littoral oceanic currents induce eddy currents in the lee of 

 promontories, either natural or artificial, and thereby shape the shore- 

 line to some form of the logarithmic spiral, r = e*^^ . Construction of 

 jetties or breakwaters extending into the currents causes the spiral 

 shoreline to form, resulting in beach erosion and prograding. The severe 

 erosion of southern California beaches is discussed. Beach changes are 

 independent of size of sand, beach slopes, depths in the foreshore, pre- 

 vailing winds, or other causes, except for currents--littoral , eddy, or 

 estuarial . 



111. LIU, P.L.F., and MEI, C.C., "Effects of a Breakwater on Nearshore 

 Currents Due to Breaking Waves," Report No. 192, Ralph M, Parsons 

 Laboratory, Massachusetts Institute of Technology, Cambridge, Mass., 

 Sept. 1974. 



Keywords: Accretion, Currents, Detached breakwater. Littoral transport. 

 Numerical model, Tombolo, Wave diffraction, Wave refraction 



This study provides a semiempirical theory of nearshore currents 

 due to breaking waves in the presence of (a) a shore-connected breakwater 

 or (b) an offshore breakwater. The effects of diffraction and refraction 

 by shoaling waters are studied. Sample results for stream functions and 

 mean sea levels are plotted for various beach profiles or incidence angles. 



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