Longshore drift

Definition

Longshore drift is the process of sediment transport along a coast, driven by the angle at which waves hit the shore. This movement occurs in a zigzag pattern as waves break, pushing sand and pebbles up the beach at an angle and then pulling them back down perpendicular to the shoreline due to gravity. This continuous movement significantly shapes coastal landforms and influences beach morphology over time.

5 Must Know Facts For Your Next Test

1. Longshore drift is influenced by prevailing wind direction, which affects wave approach angles and ultimately alters sediment transport patterns.
2. The amount of sediment moved by longshore drift can vary based on factors such as wave energy, sediment type, and coastal topography.
3. This process plays a crucial role in forming features like sandbars, spits, and barrier islands along coastlines.
4. Human activities, such as the construction of groins and jetties, can disrupt natural longshore drift patterns, leading to unintended consequences like increased erosion in other areas.
5. Understanding longshore drift is essential for effective coastal management and protecting shorelines from erosion and other processes.

Review Questions

• How does longshore drift contribute to the shaping of coastal landforms?
  • Longshore drift contributes to coastal landform development by continuously moving sediment along the shore. As waves approach at an angle, they transport sand and pebbles in a zigzag pattern, depositing them in various formations such as sandbars and spits. Over time, this ongoing process can significantly alter the coastline's appearance and influence beach morphology.
• What are the environmental impacts of disrupting longshore drift through human interventions like groins and jetties?
  • Disrupting longshore drift with structures like groins and jetties can lead to unintended environmental impacts. While these structures may protect certain areas from erosion, they can also starve down-drift beaches of sediment, leading to increased erosion elsewhere. Additionally, this disruption can alter local ecosystems by changing water flow patterns and sediment availability for various coastal organisms.
• Evaluate the importance of understanding longshore drift for coastal management strategies aimed at mitigating erosion.
  • Understanding longshore drift is vital for developing effective coastal management strategies. By recognizing how sediment moves along shorelines, planners can make informed decisions about where to place protective structures or how to implement beach nourishment programs. Effective management requires a balance between human interests and natural processes, ensuring that interventions do not inadvertently exacerbate erosion or harm local ecosystems.

Related terms

beach erosion: The removal of beach sediments due to wave action, currents, or human activities, often leading to the loss of land.

tides: The regular rise and fall of sea levels caused by the gravitational forces exerted by the moon and sun, affecting wave patterns and sediment movement.

groin: A man-made structure built perpendicular to the shoreline to trap sediment and reduce beach erosion, impacting longshore drift.