Table of Contents
What Is Coastal Erosion?
Coastal erosion occurs when the land along the coast is gradually eroded away by ocean waves and currents. The velocity of water breaks the soil and rocks and washes away in the water. This can cause the beach to shrink and change over time.
Process Of Coastal Erosion
Coastal erosion is a natural phenomenon characterized by the gradual deterioration of land and coastlines, driven by the relentless forces of waves, currents and weathering. This complex process includes several distinct phases, each contributing to the reshaping of coastlines on a global scale.
1. Hydraulic action
This initial stage involves the strong impact of waves on the coast, forcing water and air into cracks and fissures within the rock. This constant pressure weakens geological formations over time.
2. Scraping
The waves carry a mixture of sand, gravel, and large rocks, effectively acting as natural abrasives. When these materials hit the coast, they create a sandpaper-like effect, gradually eroding coastal properties.
3. Attrition
Particles transported by waves undergo a constant process of collision, with each other and with the shoreline. This continuous impact causes the particles to become smoother and smaller over time, which contributes to the overall wear process.
4. Solution
In some cases, the corrosive effect of seawater is enhanced by its acidic nature. This acidity enables seawater to dissolve soluble rocks such as limestone, further accelerating the process of coastal erosion.
5. Longshore Drift
Waves rarely approach the coast directly. They often arrive at a corner. This angular approach causes waves to carry sediment along the shoreline in a phenomenon known as offshore drift. The lateral movement of sediments plays an important role in changing the shape of the shoreline over time.
6. Deposition
While erosion is the dominant force, there are areas where transported sediment accumulates rather than being carried away. This accumulation leads to the formation of features such as beaches and spits. These sediments can greatly affect the shape of the coast.
Effects Of Coastal Erosion
- Coastal erosion gradually removes land from coastlines, reducing available space for human activities, agriculture, and development.
- Erosion threatens homes, resorts, and businesses near coastlines, causing damage and financial losses.
- Communities living close to eroding coastlines might need to move, causing disruptions and economic challenges.
- Erosion undermines the stability and functionality of roads, bridges, and other coastal infrastructure.
- Local economies can suffer due to erosion, reducing tourism, disrupting fishing industries, and lowering property values.
- Eroded beaches and coastal landmarks can deter tourists, impacting revenue for areas dependent on tourism.
- Saltwater can infiltrate freshwater sources due to erosion, impacting drinking water and agriculture.
- Eroded coastal areas often hold vital habitats for various plants and animals, leading to biodiversity loss.
- Erosion disturbs delicate coastal ecosystems, affecting marine life, vegetation, and intertidal zones.
- Erosion weakens natural barriers, making inland areas more prone to flooding during storms and high tides.
- Erosion can lead to the loss of historical sites and culturally important areas located along coastlines.
- Fishery habitats can be harmed by erosion, affecting fish populations and the livelihoods of coastal communities.
- As erosion advances, coastal communities might have to move further inland, causing changes in settlement patterns.
- Eroding coastal vegetation plays a role in carbon sequestration, so their loss contributes to climate change.
- Eroded soil ending up in water bodies due to erosion leads to sedimentation, affecting water quality and aquatic ecosystems.
- Critical infrastructure, like power plants and airports, near coastlines can be endangered by erosion.
- Erosion can reduce the availability of recreational spaces like beaches, parks, and coastal trails.
- Efforts to combat erosion, such as building seawalls or nourishing beaches, can be expensive and require ongoing maintenance.
- Communities with cultural practices tied to coastal areas, such as fishing traditions, might see their way of life threatened.
- Displacement due to erosion could contribute to the issue of climate refugees as people are forced to leave their homes.
Various Methods To Prevent Coastal Erosion
1. Jetties
Jetties are structures that extend out into the ocean and are built using materials like stone, wood, steel, or concrete. Their purpose is to prevent sand from flowing into ship channels, which could make those channels shallow over time. Shallow waters can lead to ships running aground. Jetties also serve as barriers against storm waves and littoral drift, preventing them from entering protected channels. Additionally, they help prevent erosion by redistributing sand that builds up against them along the beach.
2. Seawalls
Seawalls are built along coastlines using materials such as concrete or rocks. They act as protective barriers, preventing waves from reaching the land on the opposite side. While effective at preventing erosion, they can only safeguard the area where they are constructed.
3. Groins
Groins are wall-like structures made from materials like rocks, timber, or steel. They extend from beaches into the ocean and serve as barriers to control the movement of sand particles carried by longshore currents. When waves meet groins, they slow down, causing some of the sand to settle on the up-current side, which builds up the adjacent beach. However, this can also lead to local erosion on the down-current side, often necessitating the installation of more groins nearby.
4. Vegetation (Beach Grass Planting)
Planting special coastal vegetation like beach grass can help prevent erosion. The roots of these plants anchor the sand and prevent it from washing away during storms. While effective, this method might impact the recreational use of the beach, especially for tourists.
5. Breakwaters
Breakwaters are offshore barriers built to protect parts of the shoreline. They dissipate wave energy and cause sand carried by longshore currents to be deposited behind them, gradually building up the beach. However, the area behind breakwaters may not receive the same level of protection, leading to potential changes in beach width.
6. Beach Nourishment
Beach nourishment involves adding sand to the beach to increase its width and strength. Although temporary, it’s a way to quickly bolster the beach’s defenses. However, this method is expensive and the added sand can eventually be carried away by waves.
7. Geotextile Installation
Geotextile walls are structures made of specialized fabrics that help prevent erosion and improve soil quality. They support the construction of roads, embankments, and pipelines, protecting the ground from erosion. Different types of geotextile materials can be used based on the specific application.
8. Sand Dunes
Sand dunes form along the coast when wind carries sand onto the beach and plants help hold it in place. These dunes act as natural barriers against waves and wind, protecting the beach from erosion and helping maintain its shape.
9. Oyster Reefs
Oyster reefs are formations created by oysters in underwater environments. These reefs serve as protective barriers against waves, as oysters absorb wave energy, preventing erosion. Oysters also contribute to water quality by filtering particles from the water and providing habitats for other marine species.
10. Beach Grass Planting
Planting beach grass helps stabilize sand dunes and prevent erosion. The deep roots of beach grass hold the sand together, providing a natural defense against waves and storm surges. This method offers both protection and an opportunity to support the beach ecosystem.