For the offshore breakwater, the predicted current pattern is consistent 

 with available laboratory observations and the known tendency of tombolo 

 formation. For the shore-connected breakwater, the computed flow pattern 

 exhibits cells in both down-wave and up-wave regions, 



112. LIU, P.L.F., and MEI, C.C., "Water Motion on a Beach in the Presence 

 of a Breakwater, 1. Waves, 2. Mean Currents," Journal of Geophysiaal 

 Researah^ Vol. 81, No. 18, June 1976, pp. 3079-3094. 



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

 Numerical model, Tombolo, Wave diffraction. Wave refraction 



For a long breakwater on a slowly varying bottom, an asymptotic 

 theory is given which accounts for the combined effects of refraction 

 and Fresnel diffraction of water waves. Numerical examples are given 

 for an offshore breakwater and an isolated jetty, 



A semiempirical theory of breaking-induced mean currents on a beach 

 is developed to study the combined effects of refraction and diffraction. 

 With the omission of convective inertia and lateral turbulent diffusion, 

 the resulting averaged equations are solved by finite differences. The 

 case of an offshore breakwater is studied in detail, and the predicted 

 current pattern is consistent with laboratory observations and the known 

 tendency of tombolo formation near sandy beaches. Numerical results for 

 an isolated breakwater extending from the shore are also presented. 



113. LO GATTO, D., "Construction of Ports on Sandy Shores," Report to 

 SII-Q3, Xlth Intemati-onal Navigation Congress ^ Saint Petersburg, 

 U.S.S.R., 1908. 



Keywords: Accretion, Detached breakwater, Downdrift beaches, Italy 



(Chiavari and Salerno), Littoral transport. Segmented break- 

 water, Tombolo 



The construction of ports on sandy coasts presents serious prob- 

 lems to the designer. Provision must be made for dealing with the 

 littoral materials moving down the coast. Port structures can be either 

 perpendicular to shore as jetties or parallel to shore as detached break- 

 waters. Detached breakwaters at Salerno and Chiavari have been used to 

 protect eroding shorelines where the use of groins had previously failed. 

 The placement of harbor structures must be planned to eliminate or reduce 

 required maintenance dredging. To achieve this end, the idea of a "neu- 

 tral axis" is presented. Seaward of the neutral axis no material can be 

 moved to the shore. 



114. LOGACHEV, L.A., LYZLOV, L.A., and MIROSHNICHENKO, V.G., Untitled 

 report to SII-S2 (Means of Controlling Littoral Drift to Protect 

 Beaches, Dunes, Estuaries, and Harbor Entrances. Establishment of 

 Artificial Beaches) , XXIIId International Navigation Congress ^ 

 Ottawa, 1973, pp. 259-275. 



