Coastal Transport
Weathering and erosion at the coast produces large amounts of material which is moved along the coast line and out to sea by the action of waves.
Up and down the beach: Material is moved up the beach in the swash and back down the beach in the backwash. Constructive waves move large amounts of material up the beach as they have a strong swash, whereas destructive waves move large amounts of material down the beach due to their strong backwash.
The movement of material by waves: The movement of material within the waves themselves depends on (i) the size of the material and (ii) the energy available for transporting the material. There are four possible types of transport within the water:
 | Solution - material carried dissolved in the water |
| Suspension - fine material carried suspended within the water itself |
| Saltation - material which is too heavy to be continuously held in suspension is bounced along the sea bed. |
| Traction - the heaviest material is simply rolled along the sea bed. |
Movement of material along the coastline: LONGSHORE DRIFT
The main movement of material at the coast is the movement of material along the coastline by the process of Longshore drift.
1.
Waves break on the beach at an angle controlled by the prevailing wind
direction. Material is moved up the beach in the swash.
2. Material then moves straight back down the beach in the backwash under the influence of gravity.
3. As the processes continues material moves along the coast in a zig-zag movement.
Amounts of Longshore Drift depend on:
| The strength of the waves |
| Size and amount of material available for the movement |
| Incline (slope) of the beach |
click to see annotated photograph of the longshore drift process
(make take time to download)