Coastal erosion is the loss or movement of land along the coastline. It happens when waves, currents, tides, wind-driven water, ice, or storm impacts remove sediment and rocks over time. The shoreline can move landward, and this movement can be measured over time scales like tides, seasons, and other short-term cycles. Coastal erosion is caused by forces such as water pressure, scraping by wind and water, impacts from waves, and chemical changes to rocks. These forces can be natural or human-caused.

On coasts with non-rocky materials, erosion creates rock formations where the coastline has layers of rock or fractures with different resistance to erosion. Softer areas erode faster than harder ones, forming landforms like tunnels, bridges, columns, and pillars. Over time, the coastline becomes smoother as softer areas fill with sediment from harder parts. Erosion often occurs in places with strong winds, loose sand, and soft rocks. Wind blowing sharp sand grains acts like sandpaper, wearing down and smoothing rocks. Erosion is defined as the wearing away of rock surfaces through the mechanical action of sand or rock particles.

According to the IPCC, rising sea levels due to climate change will increase coastal erosion worldwide. This will change coastlines and low-lying coastal areas significantly.

Mechanisms

Hydraulic action happens when waves hit a cliff face, pushing air into cracks in the rock. This air pressure can cause the rock to break apart over time. As the cracks grow, they may form a cave. The broken pieces of rock fall to the ocean floor, where waves continue to move them.

Attrition occurs when loose rock pieces (called scree) are moved by waves and collide with each other. These collisions grind and chip the rocks, making them smaller, smoother, and rounder. Scree also hits the base of cliffs, breaking off small pieces of rock or wearing them down, like sandpaper.

Solution is a process where acids in seawater dissolve certain types of rock, such as chalk or limestone.

Abrasion, also called corrasion, happens when waves crash against cliff faces, gradually wearing them away. Waves also use scree from other areas to hit and break off larger pieces of rock from higher parts of the cliff.

Corrosion, or chemical weathering, occurs when seawater with a pH lower than 7 (which is acidic) breaks down rocks on a cliff face. Limestone cliffs, which have a slightly higher pH, are especially affected. Wave action speeds up this process by removing the broken-down material.

Factors that influence erosion rates

The ability of waves to wear away the side of a cliff depends on many things.

The strength of rocks that face the sea affects how easily they can be worn away. This strength depends on how solid the rocks are and whether they have cracks, breaks, or layers of loose materials like silt and fine sand.

How quickly loose rock and soil from the cliff are carried away by waves depends on the power of the waves as they move across the beach. These waves must be strong enough to move material from the pile of loose debris. These piles can stay in place for many years before they are completely gone.

Beaches help reduce the force of waves before they reach the land. This helps protect the area behind the beach.

The stability of the beach, or how well it holds up against erosion, is important. Once the beach becomes stable, it should grow wider and become better at reducing wave energy. This means fewer and weaker waves will reach beyond the beach. When material from the area up the coast is carried onto the beach below the cliff, it helps keep the beach stable.

The shape of the seafloor near the coast affects how much energy waves have when they reach the shore. Features like underwater hills or ridges can reduce wave energy by making waves break and lose their strength before they hit the shore. Since the seafloor is always changing, these features can move, causing erosion to happen in different places along the coast.

Coastal erosion has increased because of rising sea levels around the world. Areas like the Eastern seaboard of the United States and parts of coastal Guyana have seen more erosion. In places such as Florida, erosion has grown worse. In response, Florida and its counties have spent more money to replace sand that has been lost, which helps attract visitors and support the tourism industry.

• Coastal erosion
• After major storms in 1997, houses on the California coast were destroyed. These storms were linked to the strongest El Niño event on record.
• Erosion of the beach at Cabrillo National Monument, California.
• Large erosion along the coast at Torrey Pines State Natural Reserve, California.
• Erosion at Torrey Pines State Natural Reserve, California, caused a scenic overlook to be moved.
• Erosion during a king tide at Dania Beach, Florida.
• Erosion of cliffs near Cromer on the Norfolk coast. The North Sea coast of East Anglia is especially vulnerable to erosion, leading to many homes being moved or destroyed over time.

• Weathering and movement of materials on slopes
• Water movement on slopes
• Plants and vegetation
• Erosion at the base of cliffs
• Accumulation of material at the base of cliffs
• How well material at the base of cliffs resists being worn away or moved
• Human activities

• Taking natural resources
• Managing the coast

Control methods

There are three common ways to control coastal erosion. These are soft-erosion controls, hard-erosion controls, and relocation.

Hard-erosion control methods are more permanent than soft-erosion controls. Examples include seawalls and groynes, which are long-lasting structures. These structures can still be damaged over time and may need repairs or rebuilding. Seawalls usually last between 50 to 100 years, and groynes typically last between 30 to 40 years. Because they are long-lasting, they are often seen as final solutions to erosion. However, seawalls can block public access to beaches and change the natural shape of the beach. Groynes also change the natural shape of the beach. Some people say groynes might reduce the time between beach nourishment projects, but they are not a complete solution. Other problems with seawalls include high costs, difficulty in maintenance, and the risk of causing more damage to the beach if built incorrectly. Hard-erosion controls can also interfere with natural water movement, stop sand from moving along coasts, and redirect stormwater to other areas.

Natural hard-erosion controls include planting or preserving native vegetation, such as mangrove forests and coral reefs.

Soft-erosion strategies are temporary solutions to slow erosion. Examples include sandbags and beach nourishment, which are not meant to last a long time. Another method is beach scraping or beach bulldozing, which creates artificial dunes to protect buildings. However, in the United States, beach bulldozing is not allowed during turtle nesting season, which runs from May 1 to November 15. Beach nourishment is a common soft-erosion method that involves moving sand from other areas to beaches to replace sand lost to erosion. This method is not always suitable, especially in areas with sand sinks or frequent large storms. Dynamic revetment, which uses loose stones to mimic natural storm beaches, may be used in high-energy areas like open coastlines.

Beach nourishment has become a controversial method for protecting shorelines. It can harm natural resources and must follow many rules and regulations. It is also expensive, and added sand may be washed away during storms. Despite these issues, many communities still use beach nourishment. Recently, the U.S. Army Corps of Engineers has suggested exploring new solutions to coastal erosion, such as protecting wetlands, planting native vegetation, and relocating buildings or debris.

Solutions that use plants to control erosion are called "living shorelines." These use natural elements like plants to protect coasts. Living shorelines are strong against storms, improve water quality, support wildlife, and provide habitats for fish. Marshes and oyster reefs are examples of natural barriers that can reduce wave energy. For example, 15 feet of marsh can absorb 50% of the energy from incoming waves.

Relocating buildings and homes farther inland is another option. This approach considers rising sea levels and erosion when rebuilding. Depending on the situation, relocation might mean moving a short distance inland or completely removing structures from an area. A method called "managed retreat" combines relocation with environmental protection efforts. While public support for relocation is often low, communities that choose this option may turn the land into public spaces or protect it through land trusts. These practices are cost-effective, help protect homes and businesses from storms, reduce pollution, create habitats for fish, restore natural areas, and preserve coastal culture.

Tracking

Storms can cause erosion to happen hundreds of times faster than regular weather. Before and after changes can be compared using data collected through manual surveys, laser measuring tools, or GPS devices attached to all-terrain vehicles. Satellite images, like those from Landsat, can be used to study coastal erosion over large areas and over many years. Special math tools can be used to measure how erosion happens and how coastlines change over time and space. These results help decide how far apart measurements should be taken in time and space to track erosion changes effectively for ecomic tracking.

Impacts

Coastal erosion causes many problems for the environment, economy, and people, especially where there are more storms and rising sea levels. It is a worldwide problem that affects coastlines in North America, Europe, Asia, and island countries. Low-lying areas and delta regions are hit the hardest. Because of these issues, scientists are studying coastal erosion more, and people are using strategies to slow it down and protect shorelines at risk.

Environmental impacts

Coastal erosion can wear away and destroy coastal landforms, such as dunes, wetlands, beaches, and barrier islands. These landforms act as natural barriers that protect against storm surges and the force of waves. When erosion causes habitat loss, it reduces the variety of plants and animals and disrupts the natural processes that support life along the coastline. Losing these features weakens the ability of coasts to withstand damage and interferes with the ways sand and soil move along the shore, as well as the habitats that support wildlife.

Economic and infrastructure impacts

Coastline erosion can damage buildings and roads, raise costs for fixing and protecting structures, and lead to the loss of homes and land. It also harms jobs and businesses near the coast, such as tourism and fishing, by narrowing beaches and changing the look and feel of the coast.

Social impacts

Coastal communities that are directly affected by erosion may be forced to move, have less access to resources like beaches or fishing areas, and are more likely to be harmed by events such as storms or flooding. In some areas, erosion has led to people moving to safer places or changing how land is used to lower risks over time.

Climate change and storm-related impacts

Climate change has caused coastal erosion in some areas because of higher sea levels, more frequent storms, and changes in how waves hit the shore. Storms, such as hurricanes and strong coastal storms, increase erosion by creating stronger waves, surges of water from storms, and movement of sand and soil. These events can quickly remove large amounts of sand and soil, weakening natural barriers like beaches and dunes and making areas more likely to erode in the future. Studies by the U.S. Geological Survey show that erosion from storms raises the risk of damage to buildings and roads and reduces the natural protection provided by beaches and dunes. Recent research also shows that rising sea levels have made erosion worse in some coastal areas, increasing the long-term risk from coastal dangers. Higher sea levels allow waves to reach farther inland, speeding up the loss of shoreline and making coastal buildings and ecosystems more at risk. Studies of the U.S. Gulf Coast have found unusually high erosion rates linked to faster sea-level rise and loss of sand and soil.

Examples

A place where erosion of a cliffed coast has occurred is at Wamberal in the Central Coast region of New South Wales. Houses built on top of the cliffs there began to collapse into the sea because waves eroded the soil and rock layers that supported the buildings.

Dunwich, the capital of the English medieval wool trade, disappeared over a few centuries due to waves redistributing sediment. Human activities can also worsen coastal erosion. For example, Hallsands in Devon, England, was a coastal village that was washed away in 1917. This happened because earlier dredging of shingle in the bay in front of the village removed material that protected the land.

The California coast, which has soft cliffs made of sedimentary rock and is heavily populated, often experiences house damage as cliffs erode. Areas like Devil's Slide in Santa Barbara, the coast near Ensenada, and Malibu are regularly affected by this process.

The Holderness coastline on England’s east coast, near the Humber Estuary, is one of Europe’s fastest-eroding coastlines. This is because the area has soft clay cliffs and strong waves. Artificial structures like groynes, which are built to control erosion, have made the problem worse farther down the coast. This is due to longshore drift, which removes sand from beaches, leaving them more vulnerable. The white cliffs of Dover have also been impacted by erosion.

North Cove, Washington, has been eroding at a rate of over 100 feet per year. This has earned the area the nickname "Washaway Beach." Much of the original town has collapsed into the ocean. North Cove is considered the fastest-eroding shore on the U.S. West Coast. Measures to slow erosion were taken, and by 2018, the process had significantly slowed.

Fort Ricasoli, a 17th-century fortress in Malta, is being threatened by coastal erosion. It was built on a fault in a headland that is naturally prone to erosion. A part of one of the fortress’s walls has already collapsed because the land beneath it eroded. Cracks have also appeared in other walls.

In El Campello, Spain, the erosion of a Roman fish farm, which was carved into rock during the first century B.C., was made worse by the construction of a nearby sports harbor.

Hampton-on-Sea, located in Kent, England, has suffered from coastal erosion since before the 1800s. The area was once popular for oyster fishing and relied heavily on the sea. Coastal erosion worsened with global warming and climate change, which caused rising sea levels, stronger and more frequent storms, and increased ocean temperatures and rainfall. Storms also damaged the Hampton Pier, Hernecliffe Gardens, several villas, roads, and other structures. In 1899, a sea wall was built to protect the remaining land and buildings. However, the wall did not stop erosion, and a later storm broke it, flooding the land behind it. These events led to the abandonment of Hampton-on-Sea. By 1916, the town was completely deserted. By the 1920s, only a few buildings remained. Today, only three landmarks remain: The Hampton Inn, The Hampton Pier, and a few roads. The Hampton Pier is smaller than the original but is still used for fishing.

A study published in Earth's Future, a journal by the American Geophysical Union in 2025, shows that coastal areas in arid regions, such as those in the Mediterranean, are severely affected by erosion. For example, in 2025, more than 7,000 buildings in Alexandria, a harbor city, are at risk of collapsing due to erosion and changes in groundwater.

In South America, the Chilean coast has experienced erosion on certain beaches due to an increase in severe storms during warm phases of the El Niño-Southern Oscillation phenomenon.