All coastlines are impacted by storms and other natural events that cause coastal erosion.
These occurrences prompt erosion because local sea levels will rise, strong wave action will occur, and coastal flooding will wear down or wear away the rocks, land, and sand making up a coastline.
This negatively affects the environment as well as the economy in these coastal communities.
If you’re considering purchasing land on the coast in the United States, read about coastal erosion before you do!
1. What is coastal erosion?
Coastal erosion is the loss or displacement of land.
It occurs when sediment and rocks along the coastline move because of waves, currents, tides, wind-driven water, waterborne ice, and other impacts of storms.
As it retreats, the shoreline can be measured and described over a temporal scale of tides, seasons, and other short-term cyclic processes.
2. What causes coastal erosion?
Coastal erosion is caused by the following…
Hydraulic action
When waves strike a cliff face, they compress air in and exert pressure on the surrounding rock.
This can cause the rock to progressively splinter and even break off.
Over time, the cracks may even form a cave and fall into the sea bed when more waves crash into the rock.
Attrition
This cause of erosion occurs when waves prompt loose pieces of rock debris to collide with each other.
The pieces may grind and chip each other, causing them to progressively become smaller, smoother, and rounder.
The debris may also collide at the base of the cliff face and chip small pieces of rock from the cliff.
This is sometimes compared to sandpapering.
Solution
When acids are contained in seawater, they can dissolve some types of rocks like chalk or limestone.
Abrasion
Abrasion is sometimes known as corrasion.
It occurs when waves break off cliff faces and slowly erode them.
When water pounds cliff faces, it uses the splintered rock to batter and break off pieces of rock from higher up on the cliff.
Corrosion
This type of erosion is solution or chemical weathering.
It occurs when the sea’s pH (anything below pH 7.0) corrodes rocks on a cliff face.
Limestone cliff faces are often eroded in this way because they have a moderately high pH.
Wave action also increases the rate of reaction by removing the material that’s been impacted by corrosion.
3. What is coastal transportation?
Coastal transportation is a means of coastal erosion and describes the movement of material in the sea and along the coast by waves.
The movement of material along the coast is called longshore drift.
Longshore drift occurs when waves approach the beach at an angle.
Waves will carry material up, along the beach.
The backwash of the sea will then carry material back down at right angles because of gravity.
This process moves material slowly along the beach.
Overall, longshore drift links erosion and deposition.
The material will be eroded in one location and then transported and deposited elsewhere.
4. How does the sea transport material?
“Longshore drift” is the main process of transportation, but this can occur in four ways.
Traction: When large material is rolled along the sea floor
Saltation: When beach material is bounced along the sea floor
Suspension: When beach material is suspended and carried by waves
Solution: When beach material is dissolved and carried by water
5. What is shoreline hardening?
To prevent coastal erosion and provide flood protection, shoreline hardening has been used historically.
This is the installation of artificial structures such as concrete or steel walls as well as riprap borders consisting of large stones or boulders.
However, as we grow to understand natural shoreline functioning, there is now a growing acceptance that shoreline hardening may not be the preferred action.
In some cases, these structural projects interfere with natural water currents.
They also prevent sand from shifting along coastlines.
Shoreline hardening measures often require significant funds to install and maintain.
Depending on the state or municipality, there may be prohibitions against these methods, which means they wouldn’t even be possible.
Furthermore, shoreline hardening can cause erosion to adjacent beaches and dunes because of the unintended diversion of stormwater and waves onto other properties.
6. What factors influence erosion rates?
The primary factors that affect erosion rates include:
The hardness of sea-facing rocks
Power of the waves crossing the beach
The stability of the foreshore (or its resistance to lowering)
Configuration of the seafloor, which controls the wave energy arriving on the coast and can have an important influence on the rate of cliff erosion
Rising sea levels globally
The secondary factors that influence coastal erosion include:
Weathering and transport slope processes
Slope hydrology
Vegetation
Cliff foot erosion
Cliff foot sediment accumulation
Resistance of cliff foot sediment to attrition and transport
Human activities
The tertiary factors that impact coastal erosion rates include:
Resource extraction
Coastal management
7. What are the control methods used for coastal erosion?
The three most common forms of coastal erosion control are soft-erosion controls, hard-erosion controls, and relocation.
Here’s what you should know about each.
Soft-erosion control
This strategy aims to slow the effects of erosion.
You’ll often see soft-erosion control techniques in the form of sandbags and beach nourishment.
That said, soft-erosion control is never meant to be a long-term or permanent solution.
It’s a temporary measure that will help slow the effects of erosion.
Another common method is beach scraping or beach bulldozing.
This permits the creation of an artificial dune in front of a building.
It allows you to preserve a building foundation.
This isn’t a good solution from May 1st to November 15th.
During this period, there is a U.S. federal moratorium on beach bulldozing because of turtle nesting.
Beach nourishment projects also help to reestablish sand lost due to erosion.
However, this action is not suitable for all areas, and over the years, it’s become a very controversial shore protection measure because it can negatively impact several natural resources.
For instance, in areas with sand sinks or large frequent storms.
If you’re attempting to treat an area such as this, you should consider dynamic revetment which uses loose cobble to mimic the function of a natural storm beach.
This is a soft-erosion control alternative that’s suitable for high-energy environments like open coastlines.
One issue with beach nourishment projects is that they must follow a wide range of complex laws and regulations.
They’re also fairly expensive to complete.
Furthermore, just because sand is added to a beach doesn’t mean it’ll stay there.
It can seem fruitless to embark on beach nourishment projects when large volumes of added sand will be washed away with the next big storm.
Despite this, many communities still choose to use beach nourishment.
The U.S. Army Corps of Engineers has emphasized the need to consider a whole new range of solutions to coastal erosion that expand beyond structural solutions.
Hard-erosion control
Hard-erosion methods are intended to be more permanent than soft-erosion controls.
You’ll often see seawalls and groynes used as semi-permanent infrastructure.
These structures are not immune from typical wear, and they will also have to be refurbished or rebuilt.
The average life of a seawall is anywhere from 50 to 100 years.
A groyne has a shorter lifespan at 30 to 40 years.
Their relative permanence allows these structures to be used as a final solution to erosion.
However, they do come with their own challenges.
Seawalls can deprive the public of access to the beach.
Both of these measures can also drastically alter the natural state of the beach.
Groynes, in particular, can reduce the interval between beach nourishment projects.
Sea walls are pricey to implement, difficult to maintain, and can sometimes cause further damage to the beach if improperly built.
Similar to soft-erosion controls, hard erosion controls come under fire.
The more we learn about these “solutions,” the more we come to believe that structural solutions create more problems than they solve.
In the end, they interfere with the natural water currents and prevent sand from shifting along coasts.
If you’re searching for a natural form of hard-erosion control, consider planting or maintaining natural vegetation.
These include mangrove forests and coral reefs.
Any solution to coastal erosion that includes vegetation is called “living shorelines.”
These use plants and other natural elements.
Living shorelines have numerous benefits including:
- Being more resilient against storms
- Improving water quality
- Increasing diversity
- Providing fishery habitats
Good examples of vegetation that can be used for living shorelines include marshes and oyster reefs.
They act as natural barriers to waves and can absorb 50 percent of the energy coming from waves.
Relocation
Consider positioning both infrastructure and housing farther away from the coast.
In the past, there has been low public support for “retreating.”
However, if a community decides to relocate their buildings along the coast, it’s common for them to turn the land into public open space or transfer it into land trusts.
This allows them to adequately protect it.
Depending on the factors like the severity of the erosion (as well as the natural landscape), relocating infrastructure could simply mean moving inland by a short distance or completely removing improvements from an area.
This is a cost-efficient way to protect from storm surges and safeguard coastal homes and businesses.
It also lowers carbon and other pollutants.
Finally, it creates nursery habitats for important species and restores open space for wildlife.
8. What is the economic impact of coastal erosion?
Coastal erosion impacts tourism, shipping, fishing, agriculture, and other industries that are dependent on coastlines.
In the U.S. alone, the damage done by coastal erosion contributes to roughly $500 million in coastal property loss.
It’s estimated that the U.S. has lost wetlands larger than the state of Rhode Island due to erosion in just the decade from 1998 to 2009 alone.
Here are some of the specific economic impacts of this issue.
Lost land
This is arguably the most significant effect of coastal erosion.
Beach, wetlands, and other shorelines erode at rates that sometimes reach 50 feet per year in areas of the U.S.
This means tens of thousands of acres of land are being lost to erosion.
Lost or damaged property
When coastal areas are eroded, it can result in direct loss or damage to property (buildings, infrastructure, etc.).
Beachfront properties like homes or businesses are threatened when this occurs.
Impacts on shipping and trade
Coastal erosion can disrupt shipping ports because it makes it more difficult for ships to reach harbors, which slows down and alters the flow of goods.
This has the potential to sharply impact trade in areas most impacted by erosion.
Revenue impacts from related industries
Countless industries rely on coastal land and property.
The most visible industry is tourism, and evidence has shown that tourists are less likely to return to areas that are suffering from continued erosion of beaches.
Other industries that are impacted include fishing, agriculture, etc.
These trades will also see effects if erosion is severe.
9. How do you protect against the economic impacts of coastal erosion?
Risk reductions can be taken to help reduce the economic influences listed above.
Measures like beach nourishments and shoreline hardening are popular tactics, but they aren’t without their drawbacks.
Coastal communities should also consider living shorelines as well as the construction of infrastructure and buildings in a way that can avoid these impacts.
10. What are the human causes of coastal erosion?
Humans can also be a leading cause of coastal erosion.
They can destroy dune grasses and disturb coastal landforms, which promotes increased erosion and movement of beach materials.
If you’re worried about causing coastal erosion on your land, here’s what you should avoid.
Off-road vehicles
Foot traffic on sand
Both of these will compact sand and destroy plant roots as well as animal burrows.
Dune grasses are an incredibly important factor in keeping sand in place and preventing water from coming too far inland.
Do your best to avoid damaging dune grasses because otherwise they can get washed away.
Final Thoughts
Anyone who has been on a beach knows how easily sand moves.
You may end up taking a little bit home with you accidentally each time you visit.
However, this incidental “erosion” can seem and be harmless on the surface, but it’s an indication of a much larger issue.
When sand, rock, and cliff are that easily removed, our shorelines can begin to disappear before our eyes.
Coastline communities must recognize this and take adequate steps to protect themselves before it’s too late.
This will ensure the land remains intact and the economy continues to thrive.
Additional Resources
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Disclaimer: we are not lawyers, accountants, or financial advisors and the information in this article is for informational purposes only. This article is based on our research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.
Prior to starting Gokce Capital, Erika received a Bachelor of Architecture from the University of Southern California and a graduate degree in Urban Policy from Columbia University. She worked as both an architectural designer and engineer in New York before joining the New York City Department of Housing Preservation and Development.
Erika currently lives in the New York Metropolitan area with her spouse, daughter and cat. She is originally from Chicago and still considers herself a midwesterner at heart.
Erika also loves to read, write and travel (fun fact, she has visited all 50 states and more than 30 countries!). Her new book, Land Investing Mistakes: 11 True Stories You Need To Know Before Buying Land, is now available on Amazon.