Coastal Erosion

Coastal Erosion is the wearing away of the land near the coastline. It removes sediments from beaches, dunes, cliffs, and coastal wetlands, mainly due to wind, waves, high tides, and storms. Coastal erosion is a natural process that shapes the world’s coastline but is also a significant environmental issue.

This article will focus on the causes, types, impacts, case studies, management studies, and some interesting facts related to coastal erosion.

Let’s explore!

Coastal Erosion

Coastal Erosion- Overview

Aspect	Description
Definition	Coastal erosion is the gradual wearing away and removal of land and sediment along the coastline by the action of waves, currents, tides, and wind.
Causes	1. Wave Action: Wave energy directly impacts the coastline, eroding and transporting sediment. 2. Sea Level Rise: Rising sea levels increase coastal erosion rates by encroaching on land. 3. Storms and Extreme Weather: Storm surges and high winds can accelerate erosion. 4. Human Activities: Coastal development, sand mining, and infrastructure can exacerbate erosion.
Processes	1. Hydraulic Action: The force of breaking waves dislodges and removes sediment from the coastline. 2. Abrasion: Waves carrying sediment scrape and wear down coastal features. 3. Attrition: Sediment particles collide, break, and become smoother over time. 4. Solution: Dissolution of soluble rock materials (e.g., limestone) by seawater.
Impacts	1. Loss of Land: Coastal erosion leads to the loss of valuable land, property, and infrastructure. 2. Habitat Destruction: Erosion can degrade and destroy coastal habitats, affecting biodiversity. 3. Economic Costs: Damage to coastal properties, tourism sites, and infrastructure results in economic losses. 4. Storm Surge Vulnerability: Eroded coastlines are more susceptible to storm surges and flooding.
Management Strategies	1. Hard Engineering: Structures such as seawalls, groynes, and breakwaters to protect the coastline. 2. Soft Engineering: Beach nourishment, dune restoration, and vegetation planting to stabilize coastlines. 3. Managed Retreat: Relocation of vulnerable coastal communities away from eroding areas. 4. Regulatory Measures: Zoning laws, building codes, and setback requirements to regulate coastal development.

Meaning of Coastal Erosion

Coastal erosion is the wearing away of the land by the action of natural processes such as waves, tides, currents, and weathering. It leads to the loss of soil, sediments, and rocks from the shoreline which impacts the natural coastline. The study of erosion and sediment redistribution in coastal areas is referred to as coastal morphodynamics.

Causes of Coastal Erosion

NATURAL CAUSES	ARTIFICIAL CAUSES
Wave Action	Deforestation
Effect of Severe Cyclone	Excessive Sea Mining
Rise in Sea level	Construction of Ports and Harbours
Hide Tides	Daming of Rivers

Natural Factors

• Wave Action – High wave energy leads to the gradual removal of the land near the coastline through littoral drift. Coastal erosion caused due to wave action can never be rebuilt through natural processes. Wave action erodes the coastline over time.
• Currents – Currents erode the coastline by carrying away sand and other sediments.
• Tides – Tides are caused by the gravitational pull of the sun and moon. When the tidal energy is less, the level of coastal erosion is less whereas, when the tidal energy is more, the rate of coastal erosion is more.

Human Activities

• Deforestation – It is one of the major causes of soil erosion. Tress and other vegetation help to bind the soil together.
• Sand mining – It is the process through which the primary soil is extracted from beneath the sea. It not only lowers the groundwater level of the coast but also serves as a threat to the marine fisheries and aquatic ecosystem.
• Construction of ports and harbors – The construction of jetties, breakwaters, groins, and reclamation bunds, disturbs the natural flow of the sea which in turn blocks the coastal sedimentary transport. It alters the dune topography and coastal forest growth.

Climate Change

• Rising sea level – The rise in sea level, increases the rate of frequency of the storm, due to which the wave energy moves further inshore and erodes the coastal cliffs. Storms can further uproot and destroy the coastal vegetation which destabilizes the coastlines and increases the erosion
• Increased Rainfall – Climatic change leads to a change in the precipitation pattern. Heavy rainfall leads to increased runoff which causes coastal erosion.

Effects of Coastal Erosion

The effects of coastal erosion can be wide-ranging and significant, impacting both natural environments and human communities. Here are some of the key effects:

1. Loss of Land: Coastal erosion results in the gradual retreat of the shoreline, leading to the loss of valuable land. This can threaten coastal infrastructure, properties, and agricultural land, as well as cultural and historical sites located along the coast.
2. Habitat Degradation: Erosion can degrade and destroy coastal habitats such as beaches, dunes, wetlands, and mangroves. These habitats provide important ecosystems services, including biodiversity support, storm protection, and carbon sequestration. Loss of these habitats can lead to declines in biodiversity, loss of habitat for wildlife, and disruptions to coastal ecosystems.
3. Economic Impacts: Coastal erosion can have significant economic costs, including damage to coastal properties, infrastructure, and tourism facilities. It can also lead to loss of revenue from tourism and fisheries, as well as increased costs for coastal protection measures and shoreline stabilization efforts.
4. Storm Vulnerability: Erosion can weaken the natural protection provided by coastal features such as beaches, dunes, and barrier islands, making coastal communities more vulnerable to storm surges, flooding, and other extreme weather events. This can increase the risk of property damage, loss of life, and displacement of populations.
5. Saltwater Intrusion: As coastlines erode, saltwater from the ocean can intrude into coastal aquifers and groundwater systems, contaminating freshwater resources. This can have negative impacts on drinking water supplies, agricultural irrigation, and ecosystems dependent on freshwater habitats.
6. Cultural and Social Impacts: Coastal erosion can also have cultural and social impacts, including loss of cultural heritage sites, displacement of coastal communities, and disruption of traditional livelihoods such as fishing and agriculture. It can also lead to social conflicts over land use, property rights, and access to resources.

Coastal Erosion Examples

Here are some examples of coastal erosion from around the world:

1. Louisiana, USA: The coastline of Louisiana is experiencing rapid erosion due to a combination of factors, including subsidence, sea level rise, and human activities such as oil and gas extraction and the construction of levees. This erosion has led to the loss of thousands of acres of land, including valuable wetlands and barrier islands.
2. The Sundarbans, Bangladesh and India: The Sundarbans, the largest mangrove forest in the world, is facing significant erosion due to rising sea levels, sedimentation, and human activities such as deforestation and shrimp farming. Coastal communities in the Sundarbans are experiencing increased vulnerability to flooding and storm surges as a result of erosion.
3. Happisburgh, United Kingdom: The coastline of Happisburgh in Norfolk, England, is eroding at an alarming rate, with cliffs receding by several meters each year. This erosion has led to the loss of homes, roads, and historic landmarks, including the 12th-century church of St. Mary’s.
4. The Maldives: The low-lying islands of the Maldives are highly vulnerable to coastal erosion and sea level rise. Erosion is exacerbated by factors such as coral reef degradation, sand mining, and coastal development. The Maldives government has implemented measures such as beach nourishment and the construction of seawalls to mitigate erosion.
5. Great Ocean Road, Australia: The coastline along the Great Ocean Road in Victoria, Australia, is experiencing erosion due to wave action, storms, and sea level rise. This erosion has resulted in the loss of coastal cliffs and rock formations, including the famous Twelve Apostles.

Coastal Erosion Processes

Coastal erosion is a complex process influenced by various natural and human factors. The primary processes contributing to coastal erosion include:

1. Wave Action: Waves generated by wind and other factors exert significant force on coastal landforms, eroding and transporting sediment along the shoreline. The intensity and direction of wave action depend on factors such as wind speed, wave height, and the angle of wave approach.
2. Hydraulic Action: The force of breaking waves dislodges and removes sediment from the coastline, contributing to erosion. This process is particularly active during storms and high-energy wave events.
3. Abrasion: Also known as “corrasion,” abrasion occurs when waves carrying sediment scrape and wear down coastal features such as cliffs, headlands, and beaches. The abrasive action of sediment particles can lead to the gradual erosion of coastal landforms over time.
4. Attrition: In this process, sediment particles carried by waves collide with each other and with coastal landforms, resulting in the breaking down and smoothing of sediment grains. Attrition contributes to the process of sediment transport along the coastline.
5. Solution: Dissolution of soluble rock materials (e.g., limestone) by seawater contributes to coastal erosion in areas with limestone or other soluble rock formations. Over time, the gradual dissolution of these rocks can lead to the formation of coastal caves, arches, and other erosional features.
6. Longshore Drift: Waves breaking at an angle to the shoreline can generate a current known as longshore drift, which transports sediment along the coast. Longshore drift can lead to the gradual erosion of sediment from one area of the coastline and deposition in another, resulting in changes to coastal landforms and erosion patterns.
7. Sea Level Rise: Rising sea levels associated with climate change can exacerbate coastal erosion by increasing wave energy and inundating low-lying coastal areas. Sea level rise contributes to the erosion of beaches, dunes, and coastal marshes, leading to land loss and coastal retreat.

Types of Coastal Erosion

There are five different types of coastal erosion:-

Hydraulic Action	It takes place due to the forces of the waves hitting the coastline. The air gets trapped in the cracks of the cliff face. In due course of time, the cracks will become larger which will cause the cliff to splinter away.
Abrasion	It is a process through which the sand and small pebbles wash away from the shorelines. It is also known as the sandpaper effect. It mostly takes place during the stormy conditions.
Corrosion	It is a process where the waves wash, away the sediments, rocks, or any other material over the bottom of the sea and wear away at the surface. The process of corrosion directly leads to the process of abrasion.
Attrition	It is the process in which the already rocks from the coastline knock into each other and break apart. It causes the rocks to become smaller pebbles which eventually leads to the formation of sand.
Solution	It is the process in which the weak acidic chemicals in the seawater react with the chemicals in the rock, causing the rock to erode. Chalks and limestone cliffs are particularly vulnerable to such kind of erosion. because they contain calcium carbonate.

How to prevent Coastal Erosion?

Preventing coastal erosion requires a combination of natural and engineered solutions. Here are some strategies commonly used to mitigate coastal erosion:

1. Beach Nourishment: This involves adding sand or sediment to beaches to replenish eroded areas and restore natural coastal features. Beach nourishment can help absorb wave energy, reduce erosion, and maintain recreational and ecological values of beaches.
2. Vegetation Planting: Planting native vegetation such as grasses, shrubs, and trees along the coastline can help stabilize soil, reduce wave impact, and promote sediment deposition. Coastal vegetation also provides habitat for wildlife and enhances biodiversity.
3. Living Shorelines: Living shorelines are nature-based solutions that use natural materials such as plants, oyster reefs, and marsh vegetation to stabilize the shoreline and reduce erosion. Living shorelines can provide effective erosion control while enhancing habitat and water quality.
4. Breakwaters and Groynes: These structures are built offshore or along the coast to dissipate wave energy and protect the shoreline from erosion. Breakwaters are submerged or partially submerged barriers that reduce wave height and intensity, while groynes are structures that extend perpendicular to the shore to trap sediment and prevent longshore drift.
5. Seawalls and Revetments: Seawalls are hard structures built parallel to the shoreline to protect coastal properties from wave action and erosion. Revetments are sloping structures made of concrete, rock, or other materials that absorb wave energy and prevent erosion along the shoreline.

People Also View

• Coastal Landforms
• Top 10 Longest Coastlines in the World
• Soil Erosion

Coastal Erosion- FAQs

What are the 5 methods of coastal erosion?

The 5 methods of coastal erosion are:

• Abrasion. The process of abrasion uses sand and small pebbles to wear away and smooth out shorelines and headlands.
• Corrasion.
• Attrition.
• Solution.
• Sea Walls

What factors affect coastal erosion?

The fetch of the wave and the strength of the wind. Powerful winds and a long fetch create the most damaging (erosive) waves. The angle of the slope – steep slopes erode more violently and frequently.

What is coastal erosion in disaster management?

Coastal erosion is the process by which local sea-level rise, powerful wave action, and coastal flooding destroy or carry away rocks or sands along the shore.

What are 4 coastal erosion landforms?

Cliffs, wave cut platforms, headlands, bays, caves, arches and stacks are all coastal landforms formed by erosion.