The completed part of the beach has functioned effectively for several 

 years, including the period when exposed to Hurricane David in 1979. 



IV. SAND DUNES 



Foredunes are the dunes immediately behind the backshore (see Ch. 4, Sec. 

 VI and Ch. 5, Sec. IV). They function as a reservoir of sand nourishing 

 beaches during high water and are a levee preventing high water and waves from 

 damaging the backshore areas. They are valuable, nonrigid shore protection 

 structures created naturally by the combined action of sand, wind, and 

 vegetation, often forming a continuous protective system (see Fig. 6-25). 



(1976) 



Figure 6-25. Foredune system. Padre Island, Texas. 



1 . Sand Movement . 



Winds with sufficient velocity to move sand particles deplete the exposed 

 beach by transporting sand in the following three ways. 



6-37 



