testing program include wave height measurements at several selected 

 locations throughout the harbor area, photos of wave patterns (as shown 

 in Figs. 4-8 and 4-9), float measurements to obtain current patterns due 

 to breaking waves, and visual observations of wave action in the model. 

 Wave heights are measured by electrical wave height gages and are re- 

 corded electrically with multichannel oscillographs. The waves are pro- 

 duced by the displacement of water incident to the periodic motion of a 

 wave generator in the form of a plunger, flap, or bulkhead. A wave gen- 

 erator with a trapezoidal plunger is shown in Figure 4-10; a vertical 

 bulkhead generator is shown in Figure 4-11. 



(2) Intermediate- and Long-Period Wave Models . Operation of 

 these models is similar to short-period wave models, except that the 

 phenomenon of harbor-basin resonance becomes a primary problem that must 

 be taken into consideration. Effects of the damping coefficient on the 

 response curve (where the amplification factor is plotted versus the wave 

 frequency or wave period) must be determined and care must be taken to 

 obtain, as nearly as possible, similarity of friction in the harbor 

 basins. Wave heights are measured as before and the modes of oscilla- 

 tion are determined for each wave period that is judged important to the 

 problem under consideration. Currents at navigation openings and other 

 restricted areas in the harbor also become important for the long-period 

 wave part of the spectrum, and these currents are usually measured in 

 model studies of this type. 



5. Examples of Model Studies Conducted . 



A large number of undistorted, short -period wave action model studies 

 have been conducted worldwide, including about 35 at WES. Model studies 

 of the intermediate- and long-period seiche-type have been smaller in 

 number; only five were conducted at WES. Only a few model studies on 

 tsunamis protection have been conducted; the only one in the United States 

 was conducted by the U.S. Army Engineer Division, Pacific Ocean, concern- 

 ing proposed breakwater plans of Hilo Harbor and the city of Hilo, Hawaii, 

 for protection from tsunami damage (Palmer, Mulvihill, and Funasaki, 1967), 



Selected examples of investigations concerning short-, intermediate-, 

 and long-period model studies are discussed below. 



a. Harbor Wave Action Studies, Short-Period Waves, and Undistorted- 

 Scale Models . 



(1) Marina del Rey, Venice, California . 



(a) Project . Improvement in wave conditions. 



(b) Reference . Brasfeild (1965). 



(c) Laboratory . WES. 



(d) Test Period. January to May 1963. 



238 



