63. HAYASHI, T,, HATTORI , M. , and SHIRAI, M., "Closely Spaced Pile 

 Breakwater as a Protection Structure Against Beach Erosion," Pro- 

 aeedings of the 12 th Conference on Coastal Engineeving , American 

 Society of Civil Engineers, Vol. 1, 1968, pp. 606-621. 



Keywords: Hydraulic model (two -dimensional ) , Local scour, Pile arrays, 

 Wave reflection. Wave transmission 



A tPieory for wave transmission and reflection at a closely spaced 

 pile breakwater was developed, using the shallow-water wave theory of 

 small amplitude. An experiment on the hydraulic characteristics of the 

 breakwater was conducted in a two-dimensional wave flume. The agreement 

 between the theory and the experiment is good with respect to the co- 

 efficients of transmission and reflection of waves, and also to the 

 shoreward velocity of the jet discharged from a space between two adja- 

 cent piles. 



An experiment was also conducted on the local scouring at the foot 

 of the closely spaced pile breakwater. The maximum scouring depth at 

 the foot of the breakwater relates closely to the velocity ratio of the 

 jet to the mean fall velocity of bed material. The relationship between 

 the maximum scouring depth and the power of the jet is discussed. 



64. HAYASHI, T., KANO, T., and SHIRAI, M., "Hydraulic Research on the 

 Closely Spaced Pile Breakwater," Proceedings of the 10th Conference 

 on Coastal Engineering, American Society of Civil Engineers, Vol. 

 2, 1966, pp. 873-884. 



Keywords: Hydraulic model (two-dimensional). Pile arrays, Wave attenua- 

 tion. Wave reflection. Wave transmission 



Hydraulic properties of a row of closely spaced circular piles as 

 a breakwater have been studied both theoretically and experimentally, 

 A theory is presented for the transmission of waves past the breakwater 

 and also for the thrust and bending moment exerted by the waves on each 

 pile in the breakwater. A laboratory experiment was conducted on a 

 model structure. Close agreement is shown in the comparison between 

 the theory and the experiment with respect to the transmission coeffi- 

 cient and the bending moment distribution. 



65. HAYES, M.O., HUBBARD, D.K., and FITZGERALD, D.M., "Investigation 



of Beach Erosion Problems at Revere, Winthrop and Nantasket Beaches, 

 Massachusetts," Contract No. 2229, Metropolitan District Commission, 

 Boston, Mass., Oct. 1973. 



Keywords: Accretion, Massachusetts (Winthrop Beach), Sediment gradations. 

 Segmented breakwater 



Over the past 15 years the beaches in Boston Harbor have undergone 

 intensive erosion, particularly the popular sandy beaches of Revere, 

 Nantasket, and Winthrop. This project was undertaken to gain a better 

 understanding of the natural processes that cause this erosion and to 

 consider ways to accommodate the natural processes in dealing with the 

 problem. The study is a combination of short-term studies designed to 



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