Longshore drift is the progressive movement of sediment along a beach due to the prevailing wind and waves. This happens only if the prevailing wind is not perpendicular to the beach. The waves, in the direction of the prevailing wind go into the beach, transporting sediment with them. This is the swash. However, the backwash, instead of being parallel to the swash is in fact perpendicular to the beach. Therefore, the sediment moves down the beach. If the headlands has a turn which is more substantial than 30 degrees, a spit is formed. An Example is Spurn Point, Holderness. It is an example of a depositional landform.
Longshore drift carries sediment. Groynes can prevent this sediment from being suspended in the waves, and thus reduce erosion. An example of the ulitisation of groynes can be found at Mappleton, Holdnerness. Granite groynes were installed here in 1993 at a cost of £2,000,000. These groynes were important from Norway and brought over on a Barge.
Evidence for longshore driftEdit
- Sediment changes down the beach