from the solitary wave theory, though the ratio di-j/Ht) varies in range 

 about 1,7 to about 1^2 rather than remaining constants 



The second cong^ilation presents the results of an extensive lab- 

 oratory investigation of breaker kinematics made at the University of 

 California, I>uring the tests made on various slope beaches, a correla- 

 tion "was noted betTreen beach slope and relative breaker height o That is 

 a wave with an initial steepness of (say) 0.01, on a 1;50 slope, will 

 have a relative breaking height (Hjj/'Hj, ) of loA but on a 1:10 slope 

 Hb/Ho will be 1.7. The results still follow the general results derived 

 from the solitary wave theory, i,eo that a steep wave will break before 

 a shallow wave on a given beach, but instead of one curve, a family of 

 curves is presented. It should be noted that the field verification of 

 the solitaiy wave theory of breakers was conducted on the Scripps 

 Institution of Oceanography beach which "...Tras of an average slope of 

 approximately ls30.,."(8j Munk's' curve for relative breaker heights vs. 

 initial steepness follows quite closely the University of California 

 curve for a 1:30 slope which would seem to further verify the laboratory 

 results. 



All in all, the Iftiiversity of California proposal that beach slope 

 affects relative breaker height seems to be presented mth enough data 

 taken under controlled laboratory conditions to justify the use of its 

 index curve =, 



To find either breaker heights or depths knowing a deep water 

 height (Ho) and length (Lq), refraction diagrams must be constructed, 

 and an equivalent deep water wave height Hq' detemined from 

 Ho' = Ho X K where K is the refraction coefficient found from the 

 diagrams., The breaker heights (E\^) and depths (d^) are then determined 

 from Figures 1 and 2 by use of the ratio (H^'/Lo)" 



Height of Seawall to be Fully Effective - If we assume then, that 

 a seawall is placed at the point at "which waves would ordinarily break 

 in the absence of the wall, and that the wall has no effect on the 

 magnitude of the breaker at that point (except as noted before, to di- 

 vert part of the horizontal wave momentum on -striking the wall) to be 

 totally effective the vraill must have a height equal to or greater than 

 the crest height of the highest breaKing "wave expected. This height 

 is conroosed of two parts: The water depth plus the wave's crest height 

 above still wave level. The breaker height index (Figures 1 and 2) 

 "Will give the maximum wave height to be expected at a certain beach 

 location, provided that the deep "water wave height and steepness are 

 known. A re-view of the data presented by Reynolds (9) indicates that 

 about 6B% of the wa"VB height on breaking is above still water level. 

 Therefore, we may say, calling h-^ the height of tide above some 

 datum (MLW for example) that the "wave's crest height on breaking "mill 

 be ht + 0.7 Hb above the chosen datum. This is equivalent to stating 

 that a wall at which the maximum tide height above (say) MLW ex- 

 pected is h-i and which is founded in such depth that the maximum 

 breaker height expected is Kb, "will be totally effective if its cres"b 



