mean flow is treated as a special case of the general 

 theory, and the ratio between bottom stress and 

 surface stress is found to be dependent upon the ratio 

 of depth to bottom roughness, and is generally less 

 than 0.1. 



NO. 94 - May 1957 



I-C "Preliminary Report: Laboratory Study of The Effect of an 

 Uncontrolled Inlet on the Adjacent Beaches" by Thorndike 

 Saville, Jr., Joseph M. Caldwell, and Henry B. Simmons 



Initial results of a series of laboratory tests made to 

 determine the manner in which beach processes in the 

 vicinity of a tidal inlet differ from those outside the 

 influence of the inlet, and the adjustments which can 

 be expected to occur in a previously unbroken beach 

 following introduction of an inlet, are presented. 

 The laboratory tests were run in two parts, one without 

 the inlet in place and one with the inlet cut through. 

 No attempt was made to model any particular inlet in 

 nature or any hypothetical prototype. Results are pre- 

 sented in photographs and hydrographic sheets in color. 



NO. 95 - May 1957 



I-A "Effect of Bottom Roughness on Wind Tide in Shallow Water" 



C by E. G. Tickner 



F 



This report presents the results of a laboratory study 

 of the effect of bottom roughness on both set-up and 

 wave generation, utilizing equally spaced strips of 

 window screening to represent the roughness. It is 

 shown that roughness increased the set-up over that for 

 smooth bottcHTi conditions by as much as two times when 

 the water depth was slightly above the roughness top, 

 though decreasing it to a negligible amount when the 

 water depth was about half-way up on the roughness 

 strips. Wave heights were not appreciably affected for 

 large depths over the roughness tops, but were reduced 

 for small depths; generally wave heights could be 

 predicted adequately by using an "effective" depth 

 equal to the depth over the roughness. 



109 



