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Tales of the Coast
Coastal Dynamics

Wind and Sediment

The primary method of sediment transport by wind is through saltation, or the bouncing of sediment grains across a surface. Sand grains, once dislodged, are carried up into the moving air by turbulence; they acquire energy from the moving air, and they settle through the air column due to their weight and impact on the ground.

The saltating grains impact the ground surface at a flat angle and transmit a portion of their energy to the grains on the ground. Some of the grains on the surface are dislodged and are carried upward into the flow where they continue the process of saltation; others are moved forward on the surface by the horizontal movement of the impacting saltating grains. This latter forward movement of sand on the ground surface is termed surface creep.

 

Wind and Sediment

To move sand from the beach, wind speed must exceed a threshold velocity for the particular size of sand available. If the sand is damp or if the grains must move up a slope, the velocities required for sediment transport are greatly increased.