Table 7 presents the relationship between bed- load transport Q s and flow 

 speed V for many transport formulae. The variables in Table 7 are defined 

 as follows: 



Q s = volumetric bed -load transport 

 A, m, n = empirical coefficients 



t = shear stress at the bed (r = p U2) 



r c = critical shear stress at the bed (r c = p M*\) 



U* c = critical threshold shear speed 



S = energy grade line 



U* = average shear speed 



D = grain diameter 



f = friction factor 



u,,, = maximum horizontal orbital speed 

 90. There obviously is a wide range in the power to which speed is 

 raised in the sand transport relationships. The 3.5 to 4.6 range determined 

 in the laboratory is reasonable if compared to the transport formulae present- 

 ed in Table 7. Sawamoto and Yamashita (1986) related bed -load transport to 

 the cube of the speed for a sheet flow condition, which agrees well with the 

 powers of flow speed determined in the present experiment program. Kraus , 

 Gingerich, and Rosati (1988) compared results from the SUPERDUCK field data 

 collection project to the expression for sand transport given by Katori et al . 

 (1984) and found that the field data agree well with Katori et al.'s transport 

 formula expressed in terms of the flow speed cubed. Kraus, Gingerich, and 

 Rosati (1988) developed an equation relating the total immersed weight 

 longshore sand transport rate to a discharge parameter R = h£ V , where H b 

 is the breaking wave height if the surf zone bed is approximated as a plane 

 sloping surface. The breaking wave height, however, is directly proportional 

 to the maximum wave orbital velocity u,,,. Therefore, the equation given by 

 Kraus, Gingerich, and Rosati (1988) expresses the sand transport rate in the 

 surf zone as u£ V presented in Table 7. It is concluded that data from the 

 present study are consistent with laboratory and field experiments relating 

 sediment transport to flow speed raised to the 3rd or 4th power. 



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