Reprint or. re- publication of any of this material shall 

 give appropriate credit to the U. S. Army Coastal Engineering 

 Research Center. 



Limited free distribution of this publication within the 

 United States is made by the U. S. Army Coastal Engineering 

 Research Center, 5201 Little Falls Road, N. W. , Washington, 

 D. C. 20016 



The contents of this report are not to be used for ad- 

 vertising, publication, or promotional purposes. Citation 

 of trade names does not constitul^e an official endorsement 

 or approval of the use of such commercial products. 



The findings in this report are not to be construed 

 as an official Department of the Army position unless so 

 designated by other authorized documents. 



