Coastal erosion

Coastal erosion is the slow loss of land along the coast. It happens when waves, currents, tides, and storms wear away rocks and soil. This process can shape the coastline in many interesting ways, creating natural features like tunnels, bridges, columns, and pillars.

Erosion is especially strong where the land has soft rocks and loose sand. Strong winds can blow sand that slowly wears down rocks.

Because of climate change, sea levels are rising. This makes coastal erosion happen more quickly and in more places around the world. As the oceans get higher, many coastlines will change over time.

Mechanisms

When waves hit the land near the ocean, they can wear it away in several ways.

First, hydraulic action happens when waves push air into cracks in cliffs. This pressure can break small pieces of rock, which fall into the water.

Next, attrition occurs when small rocks bump into each other as waves move them. This makes the pieces smaller and smoother over time.

Solution is when certain types of rocks, like chalk or limestone, slowly dissolve in the water.

Abrasion happens when waves crash against cliffs and use small rocks to scrape away at the rock on the cliff.

Finally, corrosion is when the sea water wears away rocks, especially limestone.

Factors that influence erosion rates

The power of waves to wear away cliffs depends on many things. The type of rock facing the sea matters a lot. Rocks that are hard or have few cracks stay standing better, while softer rocks or those with many cracks wear away more quickly.

Beaches help protect the land by using their sand to slow down wave energy. When beaches are stable and wide, they do a better job of keeping strong waves away from the cliffs. The shape of the seafloor also plays a role. Areas where the water is shallower can cause waves to break sooner, which reduces their power when they reach the shore.

Rising sea levels around the world have increased coastal erosion in many places.

Control methods

There are three main ways to help stop coastal erosion: soft-erosion controls, hard-erosion controls, and relocation.

Hard-erosion controls, like seawalls and groynes, are meant to last longer but still need regular care. They can be costly and sometimes cause other problems. Natural options for hard-erosion control include growing mangrove forests and protecting coral reefs.

Soft-erosion controls are temporary fixes, such as using sandbags or adding extra sand to beaches, called beach nourishment. These methods help for a short time but aren’t permanent solutions. Another soft method is dynamic revetment, where loose rocks mimic a natural storm beach to protect the coast.

Living shorelines use plants and natural materials to fight erosion. They are strong during storms, help keep water clean, and support wildlife. Examples include marshes and oyster reefs.

Relocation means moving buildings and infrastructure farther from the coast to safer places. This helps protect homes and nature and creates open spaces for wildlife. It’s a cost-effective way to prepare for rising seas and erosion.

Tracking

Strong storms can make erosion happen faster. We can see changes in the coast by looking at pictures and measurements taken before and after storms. Tools like laser height-measurers and GPS devices help us track these changes. We also use satellite images to study large areas over many years. These methods help scientists learn how coastlines change and plan how to protect them.

Impacts

Coastal erosion changes the environment and affects communities. It is a problem in many places around the world, from North America to Europe, Asia, and island nations. This is especially hard for low-lying areas and places where rivers meet the sea. People are working to protect shorelines and reduce erosion.

Environmental impacts

Coastal erosion can wear away important places like dunes, wetlands, beaches, and barrier islands. These places help protect us from strong storms and big waves. When erosion takes them away, it can hurt plants and animals that live near the coast and make the area weaker against natural changes.

Economic and infrastructure impacts

When the coast erodes, it can damage buildings and roads near the water. This means people need to spend more money to fix and protect these places. It can also cause loss of land and property.

Coastal erosion can affect jobs and activities near the coast, like tourism and fishing. When beaches get smaller and the environment changes, it can be harder for these activities to continue.

Social impacts

Coastal communities affected by erosion may need to move because their land is disappearing. They also have less access to resources near the coast and face more danger from natural events like storms. In some places, people have had to change where they live or how they use the land to stay safe in the future.

Climate change and storm-related impacts

Climate change has made coastal erosion worse in many places. Rising sea levels, more frequent storms, and changes in wave patterns all play a part. Big storms, like hurricanes, can speed up erosion a lot. They bring strong waves and high water that move sand and rock away quickly. This weakens beaches and dunes, which normally protect the land. Rising sea levels also make erosion happen faster in some areas. As the water gets higher, waves can reach further onto land, making the shore move back more quickly. This puts buildings and natural areas near the coast at greater risk.

Examples

Coastal erosion happens when waves and water wear away land near the coast. One example is Wamberal in New South Wales, where houses on cliffs began to fall into the sea because the land underneath was worn away by waves.

Dunwich in England disappeared over many years because waves moved sand and dirt away. Human actions can make erosion worse. Hallsands in Devon, England, was washed away in 1917 after people removed sand from the bay in front of it.

In California, soft cliffs often erode, causing damage to homes. Places like Devil’s Slide and Malibu see this problem often. The Holderness coastline in England erodes quickly because of soft clay cliffs and strong waves. Efforts to stop it have sometimes made the problem worse elsewhere.

North Cove in Washington loses land each year, earning it the name “Washaway Beach.” Many parts of the town have fallen into the ocean. Work was done to slow the erosion.

Old buildings and towns around the world face similar challenges. In Malta, a historic fortress is threatened as the land under it erodes. In Spain, an old Roman fish farm has been damaged by erosion.

Hampton-on-Sea in England was once a popular place for fishing but had to be abandoned because erosion destroyed too much land. Today, only a few structures remain.

Coastal areas in dry regions, like the Mediterranean, are at risk. In South America, some Chilean beaches erode more during strong storms.