n 5 Zll 2.1/2 3h ,. ., 



D^ = ^ pg ' K A ' (A-5) 



in which A is the scale parameter in the equilibrium beach profile 



h (y) = Ay^/^ (A-6) 



(b) Energy Dissipation by Bottom Friction . The wave energy dissipation 

 per unit volume due to bottom friction, D„, is 



in which Cf is a bottom friction coefficient, u^ is the bottom water 

 particle velocity and the overbar indicates a time average. For linear 

 waves, equation {A-7) can be reduced to 



sinh kh 

 The activity coefficient C-^pp, outside the surf zone, is expressed as 



1 °2 -5 



Cqpp = -^^ X 10 ^ ft/s, h > h^ (A-9) 



^OFF = 5-r gV^Xm, {^drhf ' 10"' (^-1°^ 



in which r is a parameter relating the efficiency with which breaking wave 

 energy (which occurs primarily near the water surface) mobilizes the sediment 

 bottom (0 < r _< 1). Herein, r is taken to be one. 



Figure A-2 presents an example of the variation of the activity 

 coefficient versus relative depth for a particular wave period and deep water 

 wave height. It is seen that the activity coefficient reduces rapidly with 

 increasing depth. 



The value of Cqff ^^^ ^^^ physical modeling of Savage's (1959) data 

 was taken as 10"^ feet per second. Perl in (1978) presents some rationale 

 for choosing a value of CqfF' however, very little testing has been done 

 and none is based on actual field measurement. 



58 



