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Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle, shells) along a coast parallel to the shoreline, which is dependent on the angle of incoming wave direction. Oblique incoming wind squeezes water along the coast, generating a water current that ...
Longshore drift by swash occurs either due to beach cusp morphology or due to oblique incoming waves causing strong alongshore swash motion. Under the influence of longshore drift, when there is no slack-water phase during backwash flows, sediments can remain suspended to result in offshore sediment transport.
In this case, longshore drift as well as prevailing wind and waves bring sediment together from opposite directions. [2] If there is a large angle between the waves and the shoreline, the sediment converges, accumulates, and forms beach ridges. [2] [5] Over time, a cuspate foreland forms as a result of continued accretion and progradation. [4]
The endless cycle of swash and backwash and resulting beach drift can be observed on all beaches. This may differ between coasts. Rhossili in Wales is a low-energy shoreline. Probably the most important effect is longshore drift (LSD)(Also known as Littoral Drift), the process by which sediment is continuously moved along beaches by wave action ...
It is still debated what process or processes have resulted in this odd structure, though longshore drift is the most accepted hypothesis. Studies have been conducted since 1892 to determine the speed of boulder movement. Rates of the top-course gravel movement have been estimated at 7.5 metres a year. [21]
It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift by longshore currents. The drift occurs due to waves meeting the beach at an oblique angle, moving sediment down the beach in a zigzag pattern. This is complemented by longshore currents, which further transport sediment through the ...
Longshore drift of sediment is important for distributing sediment along the coast, and is considered one of the most important mechanisms. [5] The longshore drift of sediment can be considered both a source and a sink due to the fact that in some case it can add sediment to a coastline but in others transport sediment away from a coastline.
It reduces erosion on the other, i.e. downdrift, side by reducing the speed and power of the waves striking the shore. It is a physical barrier to stop sediment transport in the direction of longshore drift (also called longshore transport). If a groyne is correctly designed, then the amount of material it can hold will be limited, and excess ...