Long shore drift Notes

Long shore Drift

Waves can approach the beach at an angle because of the prevailing wind. The swash of the waves carries material up the beach at an angle and the backwash takes back down into the sea at 90°. This movement is called transportation. Continual swash and backwash transports material sideways along the coast. This movement of material is called long shore drift and occurs in a zigzag.

What is Long shore drift?

How does long shore drift erode the beach?

Long shore drift is moving sediments from one part of the beach and depositing it somewhere else. This means it is removing parts of the beach and thus is eroding it. This leaves the cliff vulnerable as the beach gets smaller and there is nothing to protect the beach. Because of this waves can continue attacking cliffs.

How can you stop the effects of Long shore drift?

A special type of hard engineering called Groynes are used to slow down erosion caused by long shore drift.  Look like wooden “fences” that are built down the beach, at built at right angles to the coastline. They are designed to stop material being moved along the beach by long shore drift. They work by building up the amount of sand on the beach. The side of the groyne facing the waves suffers erosion, but the side protected from the waves allows deposition to occur and sand builds up there. Groynes have a life span of approximately 20 to 30 years.

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