the amount of loss remaining after all known losses have been subtracted. 

 As the rate of material supply into an area is increased to exceed the 

 transport capacity out of the area, or as the transport capacity along a 

 beach decreases, either sediments accumulate along the coast line or losses 

 occur to the offshore depthso As these deposits reduce the depth, the beach 

 slope assumes a profile governed by the littoral forces and the beach ma- 

 terial. Assuming material characteristics to remain constant in gradation^ 

 the profile of equilibrium would be reached when all of the beach material 

 has been sorted roughly. Each size gradation assutaes its characteristic 

 slope, depending on the wave competence^ between minimum and maximum depth 

 limits governed by the material size gradation » Continued excess supply 

 would advance the berm seaward without appreciable change in profile^ 

 causing deposit of sediments in greater depths, 



103 o Losses in Submarine Canyons . - The existence of a submarine 

 canyon near the littoral berm provides a repository for important losses 

 of material into the offshore depths, When combined with a jetty or 

 breakwater, the submarine canyon may constitute an essentially complete 

 littoral barrier by drawing off all material passing around the jetty or 

 breakV'jater, Comparative surveys have been in insufficient detail to 

 enable determination of the extent of the losses of littoral material 

 into a su.bmarine canyon, 



lOlj., Losses by Deflation , - As a beach widens and the expanse of 

 permanently dry sand increases, the losses by wind deflation increase^ 

 generally resulting in the development of a dune belt immediately behind 

 the beach. Losses by wind deflation are generally difficult to determine. 

 In some instances this can be done by measurement of the increased dune 

 size between successive surveys. This would generally be more costly 

 than the information would be worth unless the problem of dune control 

 had to be considered as well as the losses of material from the beach. 

 In general, losses by wind deflation are not an important factor in the 

 design of shore structures. However, because of the aspects of dune 

 controlp some attempts have been made to devise means of measuring the 

 amount of deflation and to relate the quantities of beach sand moved to 

 the wind velocities, 



105, Experiments at the mouth of the Golurabia River^ (O'Brien 1936) 

 give an indication of the order of sand losses by wind deflation. Accord- 

 ing to typical sieve analyses, these beach sands ha.d a median diameter of 

 0,19 millimeter. Three types of sand traps were tried, two of which were 

 in good agreement as to the measured rate of sand movement, Wind veloci- 

 ties were measured during each run at points ranging between 0,25 and 

 12 feet above ground. Sieve analyses of the sand caught in the traps and 

 of the material from the surface of the beach showed variations in median 

 diameter between 0,l65 millimeter and 0,216 milliraeter. The specific 

 gravity of the sand was 2,65 and the grains were well rounded. The rate 

 of sand movement was related to the wind velocity 5 feet above the beach. 

 The measurements showed that when the velocity at this elevation was less 

 than 13 o 5 feet per second (9 miles per hour) no movement of sand occurred, 



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