How Do Seawalls Work

Sea Walls have been around for Centuries and were popular in ancient times. Sea Walls today protect cities and towns on coastlines and keep oceans from damaging businesses from flooding along with saving lives. They are massive structures that are constructed to resist the energy built up from the Ocean. How Do Seawalls Work?

A Seawall effectively acts as a form of coastal defense by redirecting the energy of a wave made by a storm surge back to the ocean water, protecting the coastline from flooding and reducing erosion of the beachfront.

A seawall is a passive structure, which protects the coast against erosion and flooding. Seawalls are often used at locations off exposed city fronts, where good protection is needed and where space is scarce. In the coming years, Seawalls will be used on coastlines worldwide in defense against rising sea levels from Global Warming.


Have you ever wondered how Seawalls guard our coastlines against the relentless assault of the sea? What are these colossal structures made of, and what makes them resilient? We will be looking beneath the surface, and invite you to join us on a fascinating look, as we explore the intricate details of Seawall construction. This article will provide you with an insightful and detailed look into the engineering marvel that Seawalls represent, acting as steadfast protectors of our coastal communities.

How Do Seawalls Work

The primary purpose of a seawall is to protect residential shoreline coastal areas from upland erosion and coastal defense from surge flooding. A seawall acts as an important coastal defense against these types of events. When a wave crashes onto the shore, the seawall redirects a lot of that wave energy back to the water, protecting the coastline and work to reduce erosion of the beachfront. It also protects residential areas from flooding. There are many advantages to using retaining walls along coastal beaches and inland shorelines.

Atlantic City NJ-Seawall

The environment can be protected by keeping the soil and sand from being eroded and destroyed. Many businesses thrive along the coastline that couldn’t exist without the help of a Seawall and the protection it provides.

Seawalls work to prevent sand removal, coastal protection, and dune erosion along their lengths to ensure the natural beauty of the coastline and prevent the alternative coastal erosion that is prevalent like coastal storm surges and when Hurricanes and Tsunamis rear their ugly heads below and above sea level.

Other advantages of Seawalls are:

  • They reassure the public
  • Relatively Cheap They use cheap materials like Rocks
  • They have a fairly long lifespan.

Studies suggest that flooding from rising sea levels will prove more costly than building barriers to protect coastlines is a coastal defense against beaches and development and coastal flooding brought on by Climate Change.

The storms on the East Coast alone in the last few decades have created a need for seawall structures and other protective construction projects near the shoreline that prevent disasters and huge Insurance rates that businesses and homeowners just can’t afford to pay. Insurance Companies predict that Seawalls work to protect the inland area against wave action and prevent coastal erosion will be built all around the world.

In previous years, lots of low-lying communities have been allowed to build on properties that were well under sea level. Add the fact that ocean levels have been rising for decades because of Global Warming and the risk is obvious.

The high insurance rates are already unbearable in places where people like me are from. A bad storm can create flooding in the coastal areas of New Jersey or New York.  Then after the cleanup, the higher rates are tacked on to premiums before your house is even livable.  That’s just New Jersey.  This is a growing global problem with projections saying that 5% of the world’s population lives in coastal regions that are below sea levels.

Understanding How Seawalls Work in Preventing Coastal Protection

A well-constructed Sea Wall does the job and has great positive impacts with some negative factors attached to it too. Mainly, because the wave action’s energy tends to spread out from the area that it’s built around to the neighboring areas with no protective structures. Quickly eroding public property, construction, and reducing the sand supply to their beaches.

Vertical Seawalls can cause increased damage to the development of adjacent areas of beaches that do not have seawalls. This so-called “flanking erosion” takes place at the ends of seawalls. Wave energy can be reflected from a seawall sideways along the shore, causing coastal bluffs without protection to erode faster. Some other disadvantages of a Seawall are:

  • They can make it harder to enter the beach
  • Interferes with sediment flow along the coast
  • Environmentally ugly
  • Recurved sea walls cause more significant erosion at the base of the wall

Another negative factor in building a Seawall is the maintenance cost. Even well-constructed Seawalls have a maintenance cost. Some maintenance costs will include:

  • If no weep holes are installed in the seawall, groundwater, and rain percolating through the soil will build up pressure behind it, pushing over the wall.
  • Scouring at the toe of the wall may tip the wall if there is not any toe protection.
  • Wave energy deflects down the wall, eventually destroying the ends of the wall.
  • Storms and high tides carrying debris can severely damage the seawall.

Seawalls, according to scientists have affected ecosystems along the coastline creating losses to habitats and changes in biodiversity. When natural beaches were compared to beaches with man-made structures there were large differences in the Ecology of both systems.

Harden shorelines (that are developed areas) are beaches that have Bulkheads or Seawalls built to protect against Erosion and losses in sand or land, Some areas cause damage somewhere else along with the beachfront areas.

Vertical Seawalls

Seawall Construction Methods

Although there are several different ways of constructing a seawall, there are three main methods used.

  • the first is thin, interlocking sheet piles that were driven deep into the ground.
  • The second method of seawall construction is individual piles used to support an above-ground structure.
  • The third method is a massive gravity construction resting on the shore’s bottom or embedded slightly in it. This construction is supported by its weight rather than by piling

A Large Seawall is built from concrete masonry or sheet piles and runs parallel to the shore at the transition between the beach and the mainland or dune to protect the inland area from wave action. They usually are massive structures that can resist storm surges for long periods.

Atlantic City, N.J., the U.S. Army Corps of Engineers is building a $34-million seawall-like project

The height of a vertical seawall will at least cover the difference between the beach level and the mainland, though commonly seawalls are built higher and can be straight or curved walls to protect the land against wave overtopping. Seawalls are also used to stabilize eroding cliffs and protect coastal road development and settlements.

The crest of the wall often extends into a stone area part that could be used for a road, promenade, or parking area. A seawall creates a distinct separation between the beach and the mainland. Seawalls are often found in cases of narrow or steep beaches, where a typical breakwater is too large.

A jetty platform on wooden or concrete piles is built into the sea to protect a navigation channel and it allows for the berthing of ships. It usually does not have a shore protective function which breakwaters do. Parallel jetties are frequently built to delimit a navigation channel.

Jetties will affect the longshore transport of sediment and ecological processes. Jetties can be constructed with concrete, stone, timber, or steel. Jetties are not usually adaptation measures but may be connected with seawalls or other hard coastal defense structures.

What role do these structures play in coastal defense, and how do they help in protecting inland areas from wave action? We will look into the complex marine engineering task that goes behind the construction of seawalls.

These structures have a primary function to prevent further erosion of the shoreline. They serve as a firm border for the sea and land, in some cases, they are the last defense that prevents coastal flooding. But these aren’t the only things seawalls do, they also interrupt the natural sediment transport, making them an essential part of any coastal area’s security scheme.

A seawall works as a barrier between the sea and the coast, designed to minimize the eroding impact of heavy waves. These barriers are primarily erected to protect the land and structures behind them from the aggressive action of nature’s waves and to control beach erosion. But, doesn’t any wall near the beach do the job? Well, the fact is that seawall structures are much more than mere walls. The process of seawall construction is a sophisticated engineering feat that involves applying a deep understanding of wave energy and coastal processes.

You’ll mostly see vertical seawall structures during your trips to the beach, but there are also different types of seawalls for different purposes. The make of a seawall is determined by the conditions of the sea level in that area. Some are meant for high-tide areas, others for places prone to high wave energy. These are what we call erosion seawalls. They not only offer coastal protection but also provide public access to the beach area, making these structures as recreational as they are preventive.

But how does seawall construction guarantee protection for these coastal areas? Engineering is the answer.

A seawall is designed and built taking into consideration the:

  • geographical conditions
  • marine processes
  • average sea level of the area
  • a correctly designed seawall works effectively to absorb and reduce the force of the waves, making it an important creation of coastal defense engineering. If in case a seawall isn’t designed properly, it could fail to do its job, leading to property and even loss of life.

Types of Seawalls

Seawall structures are built to protect coastlines from erosion, flooding, and wave action. There are several types of seawalls, each designed to suit specific conditions and purposes. Here are the main types of seawall structures:

  • Vertical Seawalls: These are constructed with a vertical face directly facing the sea. They are often used in areas with strong wave action and are typically made from concrete, steel, or masonry. Vertical seawalls effectively reflect wave energy into the sea but can be subject to high levels of wave impact and erosion at the base.
  • Curved or Stepped Seawalls: These seawalls are designed with a curved or stepped profile to dissipate wave energy more efficiently. The shape helps to reduce the force of incoming waves, minimizing the impact on the wall and the coastline behind it. This type of seawall is particularly effective in areas with moderate to high wave activity.
  • Mound Seawalls (Revetments): Mound seawalls are constructed using natural materials like rocks, boulders, or concrete blocks. These materials are piled up to form a sloping barrier that absorbs and dissipates wave energy. Revetments are often used in areas with lower wave energy and are valued for their ability to blend in with the natural landscape.
  • Composite Seawalls: These structures combine elements of vertical and mound seawalls to offer enhanced protection. Composite seawalls often have a vertical or curved front face with a rubble mound at the base to absorb and dissipate wave energy. This design provides robust protection against both direct wave impact and base erosion.
  • Floating Seawalls: Unlike traditional fixed seawalls, floating seawalls are designed to rise and fall with the tide. They are typically used in marinas or areas with varying water levels. Floating seawalls are anchored to the seabed but allow for vertical movement, providing effective protection against waves and minimizing the impact on marine life and sediment transport.

Each type of seawall has its advantages and is chosen based on factors such as wave conditions, coastal topography, environmental impact, and budget considerations. Effective seawall design and construction are essential for protecting coastal areas from erosion and storm damage.

Parts of a Seawall Structure

A Seawall, also known as a sea wall or a revetment, is a coastal defense structure designed to protect coastal areas from the erosive forces of the sea. Seawalls can vary in design and construction depending on the specific needs and environmental conditions of the area they are built.

They typically consist of several key components:

1. Foundation: The foundation is the base on which the seawall structure rests. It is usually made of concrete or other strong materials and is designed to provide stability and support for the wall.

2. Wall Structure: The seawall itself is the vertical or sloping structure that faces the sea. It is typically made of concrete, steel, or other durable materials. The design of the wall can vary, with some seawalls being vertical and others having a sloping or curved profile to dissipate wave energy more effectively.

3. Toe Protection: The toe of the seawall is the part that faces the water and is most exposed to wave action and erosion. To protect the toe from scour and erosion, various measures such as riprap (large rocks), concrete armor units, or other erosion-resistant materials may be used.

4. Crest or Cap: The top of the seawall may have a cap or crest that provides additional protection and helps to shed water and waves away from the wall. This can be a flat surface or have a sloping design to direct water off the wall.

5. Drainage System: Seawalls typically include drainage systems to prevent water from accumulating behind the wall. This helps reduce the risk of erosion and structural damage caused by hydrostatic pressure.

6. Revetment or Armor Layer: In addition to the main wall structure, some seawalls may have a revetment or armor layer made of stones, concrete blocks, or other materials that absorb and dissipate wave energy. This layer acts as an additional buffer to protect the seawall.

7. Backfill Material: Behind the seawall, there is often backfill material, which can be a mixture of soil and aggregate. This helps support the seawall and provides a transition zone between the wall and the natural coastal environment.

8. Anchoring System: To ensure stability, some seawalls are anchored to the shore or seabed using anchors, piles, or other anchoring systems.

9. Seabed Protection: Seabed protection measures may be employed to prevent erosion and scour at the base of the seawall. This can include the use of mats, geotextiles, or other materials to stabilize the seabed.

The specific design and components of a seawall can vary based on factors such as the local wave climate, soil conditions, budget, and the intended purpose of the seawall (e.g., protecting property, roads, or other infrastructure). The goal is to create a robust and resilient structure that can withstand the forces of the sea and provide long-term coastal protection.

Seawalls: Marine Impacts and CTCN Encyclopedia

As we explore the subject of seawalls, we need to understand that their job is far more than simply being barriers. Seawalls work with a primary function to prevent further erosion of the shoreline, protecting our beach habitat from destruction. How does a seawall do this exactly?

According to the CTCN Encyclopedia Publication & Data, It’s simple – by interrupting natural sediment transport and minimizing the eroding impact of heavy waves on beaches.

Seawalls are designed specifically to protect the inland area against wave action and prevent coastal erosion. Their construction is a mix of art and engineering science, designed to make them sturdy and prolong their lifespan.

sea wall Archives -
Sea Wall Archives

Research proves that correctly built seawalls do prevent sand removal and dune erosion along their lengths. Seawall structures are carefully engineered to not only safeguard coastal areas but to also ensure they don’t negatively disrupt the surrounding environment. However, it’s a delicate balance.

Climate change and its consequences, such as rising sea levels and increased wave energy, are presenting even greater challenges to our coastal defense. This includes the erosion seawalls are designed to protect against. These challenges make the work of seawalls even more crucial. As even one strong wave carries the energy to cause significant beach erosion, seawalls take on the brunt of this energy to lessen its impact on the shoreline.

Seawalls are far more than static, vertical structures that weather the sea’s assault. They are an active part of our coastal protection efforts, requiring ongoing maintenance and adaptation to ensure they continue to perform their function well. The way a seawall works is something of an ongoing dance with the elements, with each new storm or climate shift calling for adjustments and revisions.

Seawall construction techniques have also had to adapt to our changing understanding of climate science. As sea levels rise due to climate change, new methods, and materials are being explored to ensure that our seawalls can continue to defend our precious coastlines effectively. Some of these adaptations include the innovative use of water-absorbent materials, to further reduce the wave energy shattering the wall.

Coastal flooding continues to be a persistent threat, more so in this era of climate unpredictability. To tackle this, seawalls do have to up their game. The future of coastal defense lies in holistic, sustainable solutions that not only protect against erosion but also restore and preserve the natural balance of our coastlines.

These hefty tasks are what seawalls do. And the amazing part: their work is often invisible to us. While we sunbathe on our favorite beach, little do we realize the intricate science behind the towering seawall structures around us. Thus, it is only fair that they receive the recognition they deserve. Not just as coastal barriers, but as necessary agents in climate adaptation and coastal protection.

So the next time you’re at a beach, take a moment to appreciate the seawall. Understand that it’s there doing its job to make sure you can enjoy yours. After all, there’s more to a seawall than meets the eye. There’s a world of research, engineering, and adaptation at work, helping us enjoy and maintain our beautiful coastal areas.

Seawall Construction Methods and Their Costs

The life expectancy of these types of Seawalls is between 35 years without major repairs. The average price of Seawall construction in the United States is 2.6 million dollars per/meter To combat rising waters and storm surge in Atlantic City, N.J., the U.S. Army Corps of Engineers is building a $34-million seawall-like project the Absecon Inlet Coastal Storm Damage Reduction Structure

A Seawall costs $150 to $600 per linear foot or $15,000 to $60,000 for the average residential project. Building a seawall in a commercial or high-erosion zone costs $700 to $2,000 per linear foot. A lake seawall or bulkhead for shores without heavy waves is cheaper than walls on ocean coasts.
Large vertical Seawalls like this one close to where I lived in Atlantic City NJ are very expensive to build. A very good friend of mine was contracted out by the Army Corp of Engineers to work on surveying this enormous structure. Federal monies were granted to the city for the project which was done in as little as 2 years.

The northern area of the city was destroyed during Superstorm Sandy and this project was used to revitalize that area and will finally open back up since it was closed down in 2012. Massive stones were shipped in from a Pennsylvania stone quarry to be used on the ocean side of the Seawall.

Seawall construction is not simply about piling stones; it’s a unique blend of civil engineering and marine architecture, which has the primary function of preventing further erosion of the shoreline. The seawall designs are meticulously created to protect the inland area against wave action and prevent coastal erosion. The methodologies used in the construction of seawalls are strategic, and designed to minimize the eroding impact of heavy waves. However, they must also interrupt natural sediment transport, a process critical for healthy beaches.

Erosion seawalls serve as a pivotal coastal defense structure against the aggressive attack of the sea. In many coastal areas, in the face of climate change and the rise of the sea level, these seawall structures have emerged as the first line of defense against coastal flooding. Many universities and institutions focus their research on the development of more effective and efficient seawall structures, constantly innovating with newer materials and processes for better coastal protection.

File:Seawalls.jpg - Wikipedia
Vertical & Curved Sea Wall

Among the various types of seawalls, the vertical seawall marks the hustling wave energy. Primarily made of concrete, its sheer vertical face bounces back the incoming waves, serving as an excellent coastal defense in high-energy wave environments. Though effective, the construction costs and the potential to accelerate beach erosion are concerning. For this reason, vertical seawall construction is typically limited to areas where beach preservation isn’t the primary concern.

Each type of seawall functions a bit differently, but the principle remains the same. When a wave hits a seawall, the objective is for the wall to absorb the wave energy or deflect it back into the water to prevent it from reaching the shoreline. This is how seawalls work to protect coastal areas from the devastating effects of coastal erosion.

The cost of seawall construction can vary significantly based on the materials used, the type of seawall being built, and the terrain it is being built upon. The funding for these types of projects usually comes from a mix of local, state, and federal sources. However, as the threat of climate change becomes more urgent, many municipalities are seeking new funding avenues to construct these vital defenses.

Seawall structures are a crucial part of coastal development, helping to mitigate the impacts of destructive wave action and rising sea levels. There’s a great deal more to how a seawall works than the simple barrier that many might envision; it’s not just about ‘holding back the sea’.

Rather, the engineering behind the seawall is a fascinating blend of practicality, environmental consciousness, and, at times, truly innovative design.

So, Seawalls do a lot more than we could envision. The exploration of how a seawall works brings to light the intricacies of coastal protection and the challenges faced by engineers and scientists to ensure our coasts are safeguarded against the increasing threats brought about by climate change. Their construction costs are hefty, but considering the role these structures play in defending our coasts and the communities that live there, they are indeed a worthwhile investment.

The Longevity of Seawalls: Influence and Impacts

When you take a minute to think about it, it’s pretty clear that seawalls do an impressive job. These coastal defense structures are designed to protect inland areas against wave action and prevent coastal erosion. That’s a primary function to prevent further erosion of the shoreline, but they also prevent sand removal and dune erosion along their lengths.

But, how does a seawall work to accomplish all this? And what happens when the forces of climate change, rising sea levels, and the strength of the ocean’s wave energy are set against these beach protectors? Exploring these questions gives us an insight into the science and engineering that make seawalls so critical in our adaptation to climate risks.

Climate change exerts a significant impact, particularly on coastal areas. With an increase in sea level, the likelihood of coastal flooding also grows. As a barrier designed to minimize the eroding impact of heavy waves, the seawall structures are a key component in our coastal protection strategy.

Rare mineral is the key to long-lasting ancient concrete | Nature
How Do Seawalls Work

However, even as these erosion seawalls work tirelessly, they also interrupt natural sediment transport. The vertical seawall isn’t designed to move with the beach. Instead, they stand firm to absorb and dissipate the water’s energy, their construction techniques put to the test with each crashing wave.

The construction and function of seawalls do, unfortunately, come with some drawbacks. Their presence can lead to beach erosion, a visible impact that detracts from the natural beauty and habitat of the world’s coastal zones.

However, this recognition leads to ongoing research and development to ensure that seawalls work in the most efficient and ecologically friendly way possible. Engineering teams look for ways to enhance the function of the seawall and ensure that the seawall works for as long as possible under the most challenging conditions.

Understanding these factors provides a deep perception of how a seawall works and the important role they play in our environment. Recognition of the challenges is the first step toward creating even more effective coastal defenses.

As we continue to learn and adapt, we find improved ways to manage the balance between protection and natural beauty. Knowledge of what they are, what they do, and their integral role in coastal protection brings an appreciation for these structures and the role science and engineering play in our adaptation to changing climatic conditions.

As we continue to research and better understand the nuanced relationship between seawalls and their impact on natural habitats, ongoing observation and adaptation are critical. Seawalls are increasingly important in our world where climate change and sea-level rise are evident.

They remain one of our best resources in reducing wave influence and protection from coastal flooding. Yet, we’re reminded that they interrupt the natural flow and can, over time, contribute to beach erosion. It’s a clear reminder that while seawalls do work and do their job well, maintaining them, and their environmental influence requires constant vigilance and a commitment to the balance of engineering and preservation.

The longevity of seawalls is directly influenced by these many factors. Through understanding, construction advancements, and ongoing adaptation, we ensure that the positive impact of seawalls is more significant than the disruptive. Their importance in our changing world underlines our need for continued research, learning, and adaptation to keep our coastal areas protected and thriving.


Seawalls have been around for Centuries and were popular in ancient times. Seawalls today protect cities and towns on coastlines and keep oceans from damaging businesses from flooding along with saving lives. They are massive structures that are constructed to resist the energy built up from the Ocean.

A Seawall effectively acts as a form of coastal defense by redirecting the energy of a wave made by a storm surge back to the ocean water, protecting the coastline from flooding and reducing erosion of the beachfront. Nowadays lots of structures are being built along the coast because of rising sea levels that are being brought on by Global Warming. More and more people live by the sea or have businesses there making Seawalls a very important protection for coastal communities.

JimGalloway Author/Editor



Q: Are seawall structures more than just walls?
A: Yes, seawall structures are not just mere walls. They are engineering marvels which are designed to handle wave energy and coastal processes. They take into consideration the geographical conditions, marine processes, and the average sea level of the area to effectively absorb and reduce the force of waves.
Q: Why are different types of seawalls constructed?
A: Different types of seawalls are constructed based on the conditions of the sea level in a particular area. Some are designed for high-tide areas, others for locations prone to high wave energy. They offer coastal protection and in some cases, also provide public access to the beach area.
Q: What are some of the consequences if a seawall is not designed correctly?
A: If a seawall is not properly designed, it may fail to serve its intended purpose – protecting land and structures from wave action. This could lead to property damage and potentially even loss of life.

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