T.M. No. 125 (Continued) 



the relative size of the crest length and wave length, but this 

 is believed to be mathematical rather than physical, depending on 

 the assumed form of solution. A comparison is afforded between 

 properties of short-crested and long-crested waves. 



T.M. No. 126 - July 1961 



Equilibrium Characteristics of Sand Beaches in the Offshore Zone 

 by P. S. Eagleson, B. Glenneand J. A. Dracup 



The report describes a theoretical and experimental investigation 

 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 modification. Sorting experiments 

 bear out qualitative theoretical predictions of increase in size 

 sorting in the onshore direction and tendency toward formation of 

 bi-modal size-f requ'ency distribution. 



T.M. 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 determine 

 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 protective beach over a 3-year period 

 equal to or greater than minimum dimensions required. Average annual 

 losses have been about 13,000 cubic yards per year, and the feeder 

 beach has performed satisfactorily. Size and sorting characteris- 

 tics of the fill material are shown to have been suitable , using 

 Krumbein's method of computed composite curves. Borrow sources, 

 although only 1,000 feet offshore, were suitable for wave condi- 

 tions 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 linear foot of shore protected. The groins are effective 

 and have probably reduced fill losses to a degree justifying their 

 construction . 



38 



