Longshore Drift Made SIMPLE

So you want to know about longshore drift? Well, you have come to the right place! Longshore drift might sound complicated, but believe me its actually not. And in this article I will explain in SIMPLE terms what longshore drift is, how is works and why it is important. Ready to learn more? Read on…

Contents

What is longshore drift?

Longshore drift is the process by which sediment (such as sand and small rocks) is transported along a beach or coastline by the movement of water.

As waves approach the shore at an angle, they carry sediment along the beach in a zigzag pattern.

When the waves retreat, the sediment is deposited, creating a buildup of sand or rocks.

This process repeats over time, gradually moving sediment along the shoreline.

Longshore drift is an important natural process that helps shape the coastal landscape.

How does longshore drift work?

Longshore drift works like this:

Waves approach the shore at an angle, usually influenced by the prevailing winds and ocean currents.
As the waves hit the beach, they lose some of their energy and deposit sediment (such as sand and rocks) on the shore.
The waves then retreat back into the ocean, but at an angle that is slightly different from the angle at which they approached.
As the waves retreat, they pick up sediment from the beach and carry it back into the ocean.
This process of sediment transport repeats over time, gradually moving sediment along the shoreline.
The direction and speed of longshore drift is influenced by many factors, including the shape of the coastline, the strength and direction of the waves, and the type of sediment present on the beach.

Longshore drift is an important natural process that helps to shape the coastal landscape over time. It can also have significant impacts on coastal erosion and sedimentation patterns.

Does longshore drift move sand?

Longshore drift is a process by which sediment, including sand, is transported along a beach or coastline by the movement of water, so yes- it moves sand!

As waves approach the shore at an angle, they carry sediment along the beach in a zigzag pattern. When the waves retreat, the sediment is deposited, creating a buildup of sand or rocks. This process repeats over time, gradually moving sediment along the shoreline.

The diagram above demonstrates how this process occurs.

How does longshore drift affect the coastline?

Longshore drift can have significant effects on the coastline. Here are some of the main impacts:

Erosion

Longshore drift can erode the coastline by transporting sediment away from one area and depositing it in another. This can result in the loss of beaches, cliffs, and other coastal features.

Deposition

Longshore drift can also deposit sediment in certain areas, creating new beaches, sandbars, and other features. This can change the shape and composition of the coastline.

Sandbars and Spits

Longshore drift can also create sandbars and spits, which are long, narrow features that extend out into the ocean. These features can create sheltered areas for boats and other watercraft.

Coastal Flooding

Longshore drift can also contribute to coastal flooding by changing the shape and composition of the coastline. This can result in changes to the way that waves and currents interact with the shoreline.

Does longshore drift stabilise beaches?

Longshore drift can both destabilise and stabilise beaches, depending on various factors. Here are some ways that longshore drift can stabilise beaches:

Natural Protection

Longshore drift can provide natural protection to a beach by creating sandbars and spits that help absorb wave energy and protect the shoreline from erosion.

Sand Transport

Longshore drift can transport sand from one area to another, which can help to replenish a beach that has experienced erosion or loss of sand.

Sedimentation

Longshore drift can also deposit sediment along the beach, creating a buildup of sand or other materials that can stabilise the shoreline.

However, longshore drift can also contribute to the destabilisation of beaches, particularly when there is a lack of sediment or other factors that interfere with the natural processes of the coastline.

For example, when coastal development or other human activities disrupt the natural flow of sediment, this can lead to erosion and destabilisation of the beach.

Additionally, longshore drift can contribute to coastal flooding and other hazards if it causes changes to the shape or composition of the coastline.

How do you stop longshore drift?

Stopping longshore drift entirely is not possible or desirable as it is a natural process that helps shape the coastline.

However, there are measures that can be taken to manage the effects of longshore drift and protect the shoreline from erosion. Here are some ways to manage longshore drift:

Groynes

These are structures that are built perpendicular to the shoreline to trap sediment and prevent it from being transported away by longshore drift. Groynes can help to stabilise beaches and protect the shoreline from erosion.

Beach Nourishment

This involves adding sediment to a beach that has experienced erosion, to replenish the sand and stabilize the shoreline.

Breakwaters

These are offshore structures that can be used to reduce wave energy and prevent sediment from being transported away from the shoreline.

Coastal Management Plans

These are comprehensive plans that take into account the natural processes of the coastline, including longshore drift, and aim to manage these processes in a sustainable way.

It is important to note that any measures to manage longshore drift must take into account the potential environmental impacts and be based on a thorough understanding of the natural processes at work along the coastline.

Benefits and limitations of longshore drift

Longshore drift is a natural process that can have both benefits and limitations, depending on various factors. I have outlined these bellow for you:

Benefits of longshore drift	Limitations of longshore drift
Formation of new beaches and coastal landforms	Coastal erosion and property damage
Creation of habitats for marine organisms	Environmental impacts from coastal engineering structures
Opportunities for recreational activities	High costs associated with coastal management
Coastal protection from wave energy
Sediment transport helps maintain coastal processes

Lets take a look at these impacts in a bit more detail…

Benefits:

Beach formation: Longshore drift can transport sediment along the coastline, which can create new beaches and other coastal landforms.

Coastal protection: Longshore drift can help to protect the coastline from erosion by creating sandbars and spits that absorb wave energy and reduce the impact of waves on the shoreline.

Habitat creation: The deposition of sediment along the shoreline can create habitats for various marine organisms, including fish, crabs, and mollusks.

Recreational activities: Beaches created by longshore drift provide opportunities for various recreational activities, including swimming, sunbathing, and surfing.

Limitations:

Coastal erosion: Longshore drift can contribute to coastal erosion, particularly in areas where there is a lack of sediment or other factors that interfere with the natural processes of the coastline.

Property damage: Coastal properties located in areas affected by longshore drift can be at risk of damage or destruction from erosion and flooding.

Environmental impacts: Coastal engineering structures such as groynes and breakwaters can have negative environmental impacts, including altered sediment transport and changes to marine habitats.

Cost: Managing the effects of longshore drift can be expensive, particularly in areas with high levels of erosion or coastal flooding.

Longshore drift- key takeaways

Here are some key takeaways about longshore drift:

Longshore drift is a natural process that moves sediment along the coastline due to the action of waves and currents.
The direction of longshore drift is influenced by the prevailing wind and the angle of the coastline.
Longshore drift can result in the formation of new beaches and other coastal landforms, as well as providing habitats for marine organisms.
However, longshore drift can also contribute to coastal erosion and property damage, particularly in areas where there is a lack of sediment or other factors that interfere with the natural processes of the coastline.
Coastal management strategies, such as the construction of groynes and breakwaters, can be used to manage the effects of longshore drift, but these measures can also have negative environmental impacts.
Sustainable coastal management practices should take into account both the benefits and limitations of longshore drift to ensure the long-term health and sustainability of the coastline.

FAQs about longshore drift

Now that we know a bit more about longshore drift, lets answer some of the most common questions on this topic.

What is longshore drift?

Longshore drift is a natural process where sediment is moved along the coastline by the action of waves and currents.

How is the direction of longshore drift determined?

The direction of longshore drift is influenced by the direction of the prevailing wind and the angle of the coastline.

What type of sediment is typically moved by longshore drift?

Longshore drift typically moves sand and smaller sediment particles along the coastline.

Can longshore drift result in the formation of new beaches?

Yes, longshore drift can result in the formation of new beaches and other coastal landforms.

Does longshore drift contribute to coastal erosion?

Yes, longshore drift can contribute to coastal erosion, particularly in areas where there is a lack of sediment or where other factors interfere with the natural processes of the coastline.

Can coastal management strategies be used to control the effects of longshore drift?

Yes, coastal management strategies, such as the construction of groynes and breakwaters, can be used to manage the effects of longshore drift.

What are some of the negative environmental impacts of coastal management strategies designed to control longshore drift?

Coastal management strategies can result in negative environmental impacts, such as the disruption of natural sediment transport and changes to the habitats of marine organisms.

Can longshore drift impact recreational activities?

Yes, longshore drift can impact recreational activities such as swimming and beach-going, particularly in areas with strong currents.

Can longshore drift have economic impacts?

Yes, longshore drift can have economic impacts such as damage to coastal infrastructure and loss of tourism revenue.

How can longshore drift be managed sustainably?

Sustainable coastal management practices should take into account both the benefits and limitations of longshore drift to ensure the long-term health and sustainability of the coastline. This can include measures such as beach nourishment, dune restoration, and careful design and placement of coastal engineering structures.

Longshore drift: To conclude

You should now be confident to explain what longshore drift is and how it works. If you have enjoyed this article, I am sure you will like these too: