T.M. No. 155 (Continued) 



solitary wave. The third approximation to Stokes' waves in water 

 of finite depth is verified by use of classical sma I I -perturbat ion 

 expansion method. For finite amplitude waves the series expansion 

 is found to be in terms of a parameter most suitable for wave 

 lengths shorter than 8 times the depth. Rather severe restrictions 

 inherent in well-known analogy between nonlinear shallow-water flow 

 and two-dimensional perfect gas flow are pointed out. 



T.M. No. 154 - June 1963 



Beach Profile as Affected by Vertical Walls by Abdel-Latif Kadib 



Results of a laboratory investigation of some aspects of the 

 flow characteristics and wave attack at sand beaches protected by 

 a vertical seawall are reported. The effects of the top elevation 

 of the vertical wall, bed material characteristics, and different 

 wave scale ratios were also investigated. Some conclusions are 

 drawn regarding relative wall heights and beach profile stability 

 in front of and behind the wa I I . 



T.M. No. 135 - August 1965 



The Relationship Between Watershed Geology and Beach Rad ioacf i v ity 

 by John R. Byerly 



Correlation between watershed geology of the Ben Lomond Mountain 

 area, north of Santa Cruz, California, and radioactivity of beaches 

 receiving sediment from the watershed, is attempted. Radioactivity 

 of stream and littoral sediments are presented in terms of thorium 

 concentration determined by gamma-ray spectroscopy. Results are in- 

 conclusive regarding watershed geology-beach radioactivity relation- 

 ship. Radiometric determinations for littoral samples are remarkably 

 constant with low activity indicated, but considerable variation in 

 thorium content of stream sediment is found which is not consistent 

 with any known geological variation. It is concluded that studies 

 of geological maps and petrographic descriptions are not sufficient 

 to determine applicability of the radioactive tracer technique. 



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