mined for depths of 20, lj.0, 60 and 80 feet. No refraction 

 was considered, due to lack of observations. However, the 

 waves approach from the south, generally, and the contours 

 are approximately straight and parallel. No significant 

 error should result from failure to apply corrections for 

 refraction in this area for average monthly conditions. 



In deep water the individual particles of water 

 associated with progressive waves describe circles, the 

 diameter of their orbits being equal to the wave height 

 at the surface and decreasing exponentially with depth. 

 For intermediate and shallow water waves, these orbits are 

 flattened rather than being perfect circles. At any lo- 

 cation in intermediate and shallow water, these orbits 

 become more and more flattened with depth such that at 

 the bottom the motion has no vertical component and merely 

 oscillates back and forth. 



The horizontal velocity component of particle 

 motion, u, for intermediate water is given by the expression 

 (Arthur 19^1): 



•u = A(7~ cosh k(z+h) co3(kx -a^t) 

 sinh kh 



Where A is the amplitude ( Height,H ) 



( 2 ) 



k, the wave n\amber ( 2'Tf ) 



( Length, L) 



cT", the frequency ( 2 jf ) 



(Period, T) 



h, the depth of water 



and z, the depth of the particle, 

 (positive upwards) 



In shallow water: 



u = At? cos(kx -crt) 

 kh 



For the maximum horizontal particle velocity at the 

 bottom, these equations are; 



u = H 1^ for intermediate water and 



T sinh 2rrd 



u = JHL for shallow water. 

 2Td 



mM ^ »m 



