NO. 126 - July 1961 



'Equilibrium Characteristics of Sand Beaches in the Offshore 

 Zone " by P. S. Eagle son, B. Glenn and J. A. Dracup. 



The report describes a theoretical and experimental in- 

 vestigation of equilibrium profiles and sediment sorting 

 in the offshore zone, designed to test the applicability 

 of existing idealized theories to the prediction of 

 equilibrium characteristics of laboratory sand beaches. 

 Two different sediment motion equilibrium criteria are 

 considered; one in which the moments on a stationary 

 particle are in equilibrium and one in which the particle 

 is oscillating with no net motion. Results indicate 

 existing theories provide good quantitative predictions 

 of seaward limit of profile modification and whether a 

 given beach will build or erode under action of a given 

 incident wave. Quantitative prediction of profile shape 

 is good only near the offshore extreme of profile modi- 

 fication. Sorting experiments bear out qualitative 

 theoretical predictions of increase in size sorting in 

 the onshore direction and tendency toward formation of 

 bi-modal size-frequency distributions. 



NO. 127 - August 1961 



" Behavior of Beach Fill and Borrow Area at Prospect Beach , 

 West Haven, Connecticut " by William H. Vesper. 



Comparative survey and sample data are analyzed to deter- 

 mine the behavior of beach fill obtained from an offshore 

 borrow source. A groin system and feeder beach were also 

 included in the project. The project has provided a pro- 

 tective beach over a 3-year period equal to or greater than 

 minimum dimensions required. Average annual losses have been 

 about 13,000 cu. yds. per year, and the feeder beach has 

 performed satisfactorily. Size and sorting characteristics 

 of the fill material are shown to have been suitable using 

 K rumbe in* s method of computed composite curves. Borrow 

 sources, although only 1,000 feet offshore, were suitable for 

 wave conditions which have existed in the area, and shoaling 

 thereof has been limited to silty material. Annual costs 

 have been in the order of $3.00 per lineal foot of shore pro- 

 tected. The groins are effective and have probably reduced 

 fill losses to a degree justifying their construction. 



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