spectrum analyses to be made at the Board were supplied to the Ventura 

 area. Study is continuing to determine the feasibility of adapting a 

 radioactive source type density measuring instrument to be used with a 

 velocity meter to measure quantity of material pumped in bypassing 

 operations. 



(d) Laboratory Study on Relation of the Littoral Drift Rate to 

 Incident Waves. 



A series of additional laboratory tests were made in the Shore 

 Processes Test Basin to obtain further data on the relation of littoral 

 movement to incident wave characteristics. A maximum movement rate of 

 about 16,000 pounds of sand per hour (dry weight) was obtained with 

 approximately 9-inch waves. A few tests have enabled comparison of lit- 

 toral drift rates for the same average wave conditions, utilizing (1) waves 

 of a constant period, and (2) waves varying plus or minus 10 to 15 percent 

 about an average period. The indications are that the transport rate is 

 greater for the waves with varying characteristics than for the waves of 

 constant height and period. Additional work on this facet is planned for 

 the following year. A report discussing the tests and results through 

 1959 was in preparation and essentially completed. A new feeding mechanism 

 for introducing sand at the updrift end of the test beach was developed 

 and tested; a description of this equipment is contained in this Bulletin. 

 Work has also continued in an attempt to relate measured net quantities of 

 littoral accumulation at several points on the North Atlantic coast to wave 

 energy derived from statistical hindcast wave data. A report summarizing 

 this work is in preparation. 



(e) Measurement of Suspended Material in Laboratory Wave Tanks. 



Additional suspended sediment samples were obtained utilizing a 

 pump-type sampler in a wave flume using lower specific gravity coal rather 

 than sand . It is hoped that these measurements may aid in defining scale 

 relations between model and prototype measurements. Comparison is to be 

 made with measurements of sand in suspension under the same wave conditions, 

 and with waves scaled up according to the settling velocity of the sediment. 



(f) Wave Theory 



Work has continued on basic wave theory with particular emphasis on 

 determination of design wave criteria. A report "A One Dimensional Gravity 

 Wave Spectrum" was presented at the NSF-ONR sponsored conference on wave 

 spectra and is being published in their Proceedings. This paper describes 

 the wave spectrum system, its meaning, and use. A further report "A Theory 

 for Waves of Finite Height" was published in the Proceedings of the Seventh 

 Conference on Coastal Engineering. The latter report presents an exact 

 theory, which may be extended to any order. It is represented by summation 

 in harmonic series, each term of which is in an expanded form. The terms 

 of the series when expanded result in an approximation of the exact theory, 



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