T.M. No. 94 - May 1957 



Preliminary Report: Laboratory Study of the Effect of an Uncon-^ 

 trolled inlet on tiie Adjacent Beaches by Thornd i ke Savi Me, Jr., 

 Joseph 1^. Caldwell and Henry B. Simmons 



Initial results of a series of laboratory tests made to deter- 

 mine 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 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 presented 

 in photographs and hydrographic sheets in color. 



T.M. No. 95 - May 1957 



Effect of Bottom Roughness on Wind Tide in Shallow Water 

 by E. G. Tickner 



This report presents the results of a laboratory study of the 

 effect of bottom roughness on both setup and wave generation, using 

 equally spaced strips of window screening to represent the roughness, 

 it is shown that roughness increased the setup over that for smooth 

 bottom conditions by as much as two times when the water depth was 

 slightly above the roughness top, although decreasing it to a neg- 

 ligible 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. 



T.M. No. 96 - June 1957 



Factors Affecting Durability of Concrete in Coastal Structures 

 by Bryant Mather 



Both internal and external factors which affect the durability 

 of concrete structures are presented. Mixing and construction 

 practices are discussed at length. Test data from several agencies, 

 service records of concrete structures at numerous locations, and 

 a list of references are appended. 



T.M. No. 97 - July 1957 



Turbulent Flow Near an Oscillating Wall by George Kalkanis 



Results of theoretical and experimental work to define a law 

 describing the flow near the bottom due to surface waves are pre- 

 sented. Flow conditions are described mathematically for the case 



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