the beach ridge would then be determined by the maximum slope of the 

 foreshore and the run-up from Figure 2 for this particular condition. 



Also shown in Figure 1 by dashed lines is the mechanism through 

 which a wide beach berm could be formed by the seaward movement of 

 the foreshore of the beach ridge. This, of course, would only happen 

 under conditions which allow an accreting foreshore. 



Shown in Figure 3 are the stages in the development of a beach 

 ridge actually observed in the laboratory wave tank tests at the 

 Beach Erosion Board. The development apparently follcws the postulated 

 development closely in that as the slope of the foreshore steepens, 

 the height of the beach ridge is increased until a maximum is reached 

 when the slope of the foreshore becomes stable. 



The foregoing theory of beach ridge development has many important 

 ramifications for the coastal engineer. Among the most important are: 

 (1) the height of beach berms would always be limited by the imposed 

 wave conditions and the maximum run-up for particular wave steepness 

 given in Figure 2. (2) In cases where the foreshore of the beach 

 ridge would not stand on the maximum slope given in Figure 2 for the 

 particular wave steepness creating the beach ridge, the maximum 

 height of the beach berm would be determined by the run-up given for 

 the maximum stable slope of the beach ridge foreshore. 



It is realized that the processes in nature which create beach 

 ridges are much more complicated than those in the simple laboratory 

 illustration. Wave conditions are apt to vary constsmtly and the 

 tides also impose their variation. Also, things happen much faster 

 in nature where the size of the sand is considerably smaller in 

 relation to the wave height and it may not be possible to see the 

 various stages of development of a beach ridge as given here. Too, 

 in nature, development of a beach ridge would start from conditions 

 left from a previous wave train and would therefore be very unlikely 

 to have the smooth initial conditions from which the laboratory tests 

 started. It is believed, however, that the theory presented herein 

 embodies basic principles involved in beach ridge formation and that 

 knowing the basic conditions involved will lead to a better under- 

 standing of the observed phenomenon, 



REFERENCES 



1. Savage, R, P., "Wave Run-up on Roughened and Permeable Slopes," 



Paper No. 1640, WW3, Journal of the Waterways and Harbors 

 Division, Proceedings of the American Society of Civil 

 Engineers, May 1958. 



2. Saville, Thorndike, Jr., "Wave Run-up on Composite Slopes," 



Proceedings of Sixth Conference on Coastal Engineering, 

 Council on Wave Research, Engineering Foundation, 1958. 



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