Coastal Transport and Deposition

Once material has been eroded from cliffs or delivered to the coast by rivers, it must be transported and eventually deposited to create the distinctive landforms of deposition. Understanding sediment transport mechanisms is essential for explaining coastal landscapes and for evaluating the effectiveness of coastal management strategies.

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Sediment Transport Mechanisms

Sediment is transported in the coastal environment by waves, currents, tides and wind. The specific mechanism depends on particle size, available energy and the nature of the transporting medium.

Transport by Waves and Currents

Four mechanisms operate in the water:

Mechanism	Description	Particle Size	Energy Required
Traction	Large particles rolled along the sea bed by wave or current action	Cobbles, boulders (> 64 mm)	Very high
Saltation	Particles bounced along the sea bed in a series of hops	Pebbles, coarse sand (0.5-64 mm)	High
Suspension	Fine particles carried within the water column, held up by turbulence	Silt, fine sand (< 0.5 mm)	Moderate
Solution	Dissolved minerals carried invisibly in the water	Dissolved ions	Low