Longshore drift

Definition

Longshore drift is the process by which sediment is transported along the coastline, driven by the angle of wave approach and the resulting movement of water and sand. This natural phenomenon plays a crucial role in shaping coastal landforms, affecting both erosional and depositional features while influencing coastal management practices.

5 Must Know Facts For Your Next Test

1. Longshore drift occurs as waves hit the shore at an angle, pushing sand and sediment along the beach in a zigzag pattern.
2. This process can lead to the formation of various coastal features such as spits, bars, and tombolos over time.
3. Factors like wind direction, wave energy, and sediment supply all influence the rate and direction of longshore drift.
4. Understanding longshore drift is essential for effective coastal management, as it can help predict erosion patterns and sediment deposition.
5. Human activities, such as the construction of groins and jetties, can disrupt natural longshore drift and lead to unintended consequences for coastal ecosystems.

Review Questions

• How does longshore drift contribute to the formation of specific coastal landforms?
  • Longshore drift plays a significant role in shaping coastal landforms by transporting sediment along the shoreline. As waves approach the coast at an angle, they carry sand in a zigzag pattern, leading to sediment accumulation in areas where wave energy decreases. This process contributes to the development of features like spits and bars, which are formed when sediment is deposited in shallow water or along the coast, altering the landscape over time.
• Evaluate how understanding longshore drift is important for coastal management strategies.
  • Understanding longshore drift is crucial for coastal management because it helps predict erosion and deposition patterns along shorelines. By knowing how sediment moves, planners can implement strategies like beach nourishment and the placement of barriers to mitigate erosion. Additionally, this knowledge allows for better management of human interventions such as groins and jetties, ensuring they do not disrupt natural sediment flow and lead to further coastal degradation.
• Assess the potential impacts of human intervention on longshore drift and associated coastal features.
  • Human intervention can significantly impact longshore drift by altering natural sediment transport processes. Structures like groins can trap sand on one side while starving adjacent beaches of necessary sediment, leading to increased erosion. Furthermore, changes in wave patterns due to coastal development can disrupt longshore drift dynamics, affecting the formation and stability of coastal features like spits and lagoons. It’s essential to balance human needs with ecological integrity when planning coastal developments.

Related terms

wave refraction:

The bending of waves as they approach the shoreline at an angle, which affects how energy is distributed along the coast.

beach nourishment:

A coastal management strategy that involves adding sand to eroded beaches to restore their width and protect against erosion.

spit: A narrow strip of land that extends from the mainland into the water, formed by the accumulation of sediment from longshore drift.