Coastal deposition is the laying down of material on the coast by the sea. It occurs when waves lose energy or when large inputs of sediment are made into the coastal system - perhaps due to the arrival of fluvial sediment at a river estuary. Wave refraction in bays also encourages deposition due to the dispersal of wave energy. Lower-frequency constructive waves often contribute to deposition due to their strong swash, moving beach material inland.
In addition to beaches, a range of unique depositional landforms exist, including the bar, spit, tombolo and cuspate foreland. The formation of these landforms additionally depends upon the process of longshore drift. This occurs when waves approach a coast-line at an angle, due to the dominant wind. There is thus a sideways component to the swash which helps move beach material diagonally up the beach (it travels laterally as well as inshore). Backwash under gravity returns water and beach material directly to the sea (perpendicularly to the beach profile). The net result is a zig-zag or saw-tooth motion that can carry material past the end of a headland.
Depositional landforms can be highly vulnerable to erosion during extreme storm events unless vegetation colonisation has taken place. Plant roots can help anchor sediments, making them more resistant to the action of destructive waves.
Coastal deposition is the laying down of material on the coast by the sea. It occurs when waves lose energy or when large inputs of sediment are made into the coastal system - perhaps due to the arrival of fluvial sediment at a river estuary. Wave refraction in bays also encourages deposition due to the dispersal of wave energy. Lower-frequency constructive waves often contribute to deposition due to their strong swash, moving beach material inland.In addition to beaches, a range of unique depositional landforms exist, including the bar, spit, tombolo and cuspate foreland. The formation of these landforms additionally depends upon the process of longshore drift. This occurs when waves approach a coast-line at an angle, due to the dominant wind. There is thus a sideways component to the swash which helps move beach material diagonally up the beach (it travels laterally as well as inshore). Backwash under gravity returns water and beach material directly to the sea (perpendicularly to the beach profile). The net result is a zig-zag or saw-tooth motion that can carry material past the end of a headland.Depositional landforms can be highly vulnerable to erosion during extreme storm events unless vegetation colonisation has taken place. Plant roots can help anchor sediments, making them more resistant to the action of destructive waves.
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