UNCLASSIFIED 



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REPORT DOCUMENTATION PAGE 



READ INSTRUCTIONS 

 BEFORE COMPLETING FORM 



1. REPORT NUMBER 



CETA 81-10 



2. GOVT ACCESSION NO. 



3. RECIPIENT'S CATALOG NUMBER 



4. TITLE (and Subtitle) 



CRITICAL WAVE CONDITIONS FOR SAND MOTION 

 INITIATION 



5. TYPE OF REPORT a PERIOD COVERED 



Coastal Engineering 

 Technical Aid 



S. PERFORMING ORG. REPORT NUMBER 



7. AUTHORfs) 



Robert J. Hallermeier 



8. CONTRACT OR GRANT NUMBERfs) 



9. PERFORMING ORGANIZATION NAME AND ADDRESS 



Department of the Army 



Coastal Engineering Research Center (CERRE-CS) 



Kingman Building, Fort Belvoir, Virginia 22060 



D31193 



It. CONTROLLING OFFICE NAME AND ADDRESS 



Department of the Army 



Coastal Engineering Research Center 



Kingman Building, Fort Belvoir, Virginia 22060 



12. REPORT DATE 



July 1981 



13. NUMBER OF PAGES 

 16 



14. MONITORING AGENCY NAME ft ADDRESSf// d/«eron( from Controlllne Ottice) 



IS. SECURITY CLASS, (ol thla report) 



UNCLASSIFIED 



16. DISTRIBUTION STATEMENT (ol thle Report) 



Approved for public release; distribution unlimited. 



17. DISTRIBUTION STATEMENT (ol the abstract entered In Block 20, It ditlerent Irom Report) 



18. SUPPLEMENTARY NOTES 



19. KEY WORDS (Continue on rev 



Coas tal ecgjineerlng 



Coas tal processes 

 "C r iticaT~v e Toci. t y 



f necessary and identity by block number) 



Deposition 



Erosion 



Sand motion initiation 



Seaward limit 

 Wave-sand interaction 



0. ABSTRACT (Continue an reverie aide II neceaaary and Identify by block number) 



Sand and fluid characteristics together with the period of oscillatory flow 

 determine the peak fluid velocity needed for sand motion initiation. With 

 linear wave theory, this threshold peak near-bottom velocity can be used to 

 calculate critical wave conditions for sand motion — either the minimum wave 

 height in a given water depth, or the maximum water depth with a given wave 

 height, for a given wave period. The procedure presented here permits pre- 

 diction of the seaward extent of bed activity due to wave action in field and 

 laboratory situations. Example calculations are provided. 



DD 



1473 



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