5. Complex intertidal and subtidal topography controls bed form type and orientation. 

 On tidal deltas, megaripples occur on low intertidal ebb shields. Flood-oriented sand waves 

 occur in places shielded from ebb flow and transition forms occur in partly shielded areas 

 high on ebb shields or in shallow channels. In subtidal areas megaripples are superimposed 

 on the sand wave form where average velocity exceeds 80 centimeters per second. 

 Deepwater sand waves may be flood- or ebb-oriented, depending on the nature of current 

 velocity asymmetry over the bed form (i.e., flood asymmetry yields flood-oriented sand 

 wave sUpfaces). 



6. The barge-rope system enables divers to successfully observe bottom conditions in 

 current velocities up to 150 centimeters per second and depths to 7 meters. The system 

 works best at depths less than 5 meters and at current velocities less than 100 centimeters 

 per second, and in waters with good visibility (e.g., New England Coast). 



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