Last updated on November 19th, 2019
Do you know the importance of having sea walls? This is a comprehensive sea wall guide and it will outline some of the sea wall advantages and disadvantages.
Sea Wall Guide: What Are the Advantages and Disadvantages?
Climate change is a serious topic in the 21st century. With its adverse effects on the environment all around the globe, it is something that demands utmost seriousness. One significant consequence of climate change is the rise in sea levels.
A rise in sea level causes an increase in waves and tides, and this necessitates the creation of sea walls to shield various shorelines. In this guide, we will explore the sea wall advantages and disadvantages, both to the sea and land.
Coastal regions are sources of attraction for various activities such as tourism, fishing, trade, and transport. For this reason, numerous coastal management strategies have been put in place to preserve these coastlines. Since sea walls are a part of the various measures taken to protect our coastline, understanding their operation, as well as their creation, is essential.
Seawalls have been in use for hundreds of years, with the earliest spanning back to as early as 195AD. These early seawalls in Constantinople (Istanbul) were used to protect their city from damaging effects of the sea.
This shows that the structures are beneficial, and that’s why they are still in use up to date. Before we explore sea wall pros and cons, let’s first define it.
What is a Sea Wall?
A sea wall is a system of coastal defense that is constructed parallel to the coastline. The sea wall aim is to protect the shore from erosion. Also, it is used to shield areas of human habitations and leisure activities from the negative effect of waves, tides, and tsunamis action.
Since the sea walls are stationary features, they conflict with dynamic coastal nature and hinder any sediment exchange between sea and land.
Sea Wall Construction
The physical design of sea walls is highly variable; they can either be sloping or vertical and made from a wide range of materials. Sea walls come in handy in regions where further erosion on the shoreline could cause extreme damage. They range in size, type, and in the materials used for construction.
Various types of sea walls may include monolithic concrete barriers, brick or block walls, rubble mound structures, or steel sheet pile walls. They are naturally, heavily engineered, permanent structures which are most costly to design. Also, the sea walls demand a proper design, as well as construction supervision.
Since sea walls can protect the shoreline from erosion caused by waves, the structure must be very sturdy to handle the strong waves.
The design and the texture of the walls also have a significant impact on the wall’s performance. For example, while the smooth surface reflects the wave energy, irregular surfaces, on the other hand, disperse the direction of the wave.
Typically, the seawalls must have a deep foundation to enhance its stability. Also, earth anchors are mostly buried deep into the land, connected by rods to the wall to help it overcome pressure from the landward side.
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Financial Needs for Sea Wall Construction
Sea walls can be costly to construct based on the different costs involved. For example, in research done by the City of Ft. Lauderdale, they took a survey on several sea wall contractors and requested quotes.
In the study, most contractors quoted a price of $650-$2,000 per linear foot, an amount which was dependent on the location where the sea wall was to be and the waterway depth.
Additionally, there is a separate quote for other costs like permitting and engineering services which cost $2,000- $5,000 per job. The prices of construction will also vary depending on the type of material used, and the type of sea wall.
Other factors that will affect the cost of the construction include:
- Design height
The height of the sea wall directly affects the total cost of the project. Higher altitudes demand for more time of construction and materials, and hence increasing the cost per unit length.
- Anticipated wave loadings
If the expected wave loadings are high, the more flexible the structure should be. Exposed coasts and deep waters mean higher wave loadings and thus, stronger and robust walls are ideal. This, in turn, translates to higher costs.
- The number of construction stages
Costs are higher for multi-stage construction as compared to a single stage.
- The design, as well as the standard of the guard, desired
Some models will require more features than others, and therefore, they will be more costly.
- Construction materials
Based on the material used in the construction, different sea wall will have a different cost of construction. For example, various equipment such as rubble blocks, metal, pre-cast concrete elements, and soil, among others, will have different prices.
- The availability as well as the proximity of raw materials to the construction site.
- The Cost of the available human capital.
Interesting Facts about Sea Walls
Sea walls are essential mostly in areas where other beach erosion protection methods have failed, or are inadequate. In most cases, this method of protection come as the last resort. Here are facts about the sea walls you should know:
- Sea walls use is to shield the shoreline against erosion caused by sea waves. They also protect the areas near the coastline from flooding.
- Although sea walls can offer defense from flooding and erosion, they can also bring numerous problems.
- The probable change of the flow of sea waves by the presence of the wall can as well cause an increase in beach sand erosion.
- Construction of sea walls is possible both in individual and community scale. There are numerous instances where there is ad-hoc sea walls construction to protect communities and individual properties.
- Sea walls construction is costly and therefore, cost acts as a significant barrier to their construction.
- The seawalls construction can in some instances as part of a larger coastal region management plan, in conjunction with other technologies like managed realignment and beach nourishment.
Nonetheless, the topic on sea wall advantages and disadvantages is one that has been seriously researched to determine how the pros and cons weigh against each other.
Are the sea walls beneficial? Do they add more harm than good?
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Sea Wall Advantages and Disadvantages
Let’s get into our pros and cons analysis of using a sea wall along the ocean.
Advantages of Sea Walls
The numerous sea wall pros make it an ideal solution to the erosion and flooding problems experienced on coastlines.
Since it is a long-term solution, it comes with the following advantages:
- The first and foremost advantage of sea walls is that they provide excellent protection against coastal erosion and flooding from the waves. These waves can then be used as a source of renewable energy instead of being a destructive force.
- The sea wall forms a static barrier that offers a particular frontier between the sea and land.
- Unlike other coastal defenses like dikes, sea walls do not need much space for the construction. They are mostly built vertically while others are horizontal, making it space friendly.
- Sea walls are long term solutions to shoreline erosion, as compared to the soft beach nourishment.
- Sea walls are flexible in terms of adjustments and modifications. As the sea keeps posing different levels of threats that may require more defense, the sea walls update can help meet these needs. Also, with an increase in discovery on climate change, there can be an upgrade of sea walls to adapt to the new problems.
- Land in most coastal regions is a highly sought-after commodity. Therefore, since the construction of a sea wall will require area, the less the space required, the less the cost of construction.
- The sea wall construction increases security, which in turn helps to maintain hinterland values, as well as promote investment in the area.
- If there is appropriate designing of sea walls, they possess high amenity value. In various countries, they incorporate promenades which are used as attractions to promote recreation and tourism.
- The sea walls can be extremely durable as long as there is proper maintenance. For example, a sea wall constructed in Galveston, Texas in 1903, continues to offer coastal protection against erosion and flooding in the city.
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Disadvantages of Sea Walls
Despite having numerous advantages, there are also several sea walls cons that exist:
High Cost of construction and maintenance
Some people think that these structures are too expensive to build, as well as maintain.
Some designs of these sea walls might be unattractive.
If the sea walls are curved, they reflect the waves’ energy to the ocean. By doing this, the waves remain strong, which makes the walls to start eroding over time. Since most coastal lines and beaches act as an attraction to tourism, if the sea wall is unattractive, it may reduce the popularity of an area.
The construction of a sea wall also affects the availability of sediment.
This problem comes about when hard and non-erodible ones replace the soft, erodible shorelines. Whereas this will protect the valuable hinterland, its effects also cause sediment starvation problems. As a result, there will be fast rate erosion in front of the wall, but there will not be replacement of sediment through hinterland erosion.
Another probable problem of a sea wall is overtopping. Overtopping arises when the sea water levels surpass the seawall’s height making water to overflow into areas beyond the sea wall. Where the sea wall is too low, extreme overtopping might erode substantial soil and sand amounts, thus weakening the wall.
Decreased Beach Amenity Value
The continued erosion causes beach lowering, which in turn decreases beach amenity value. If there is no sea wall, natural shoreline erosion supplies the adjacent coastline stretches with sediment, through longshore drift.
Other Cons of Sea walls
- Another disadvantage is that in spite of the sea wall protecting the shoreline from erosion, the coast is still subject to natural conditions at the end of the wall. The corrosion at the end of the wall will cause the area to move inland, which makes to form a stepped appearance.
- Since the sea walls are permanent structures, they tend to interfere with some natural processes like habitat migration. The change influences the movements in sea level and therefore, sea walls act as a hindrance. They impede coastal systems’ natural inland migration in response to SLR Consulting.
- Sea walls also cause variations to the area besieged by the tides in estuaries and hence reducing the size of the area to be occupied by water during high tide.
- In some instances, the sea walls reduce the accessibility of the beach by emergency services and disabled people. In areas where the beach is for recreation activities, the inaccessibility can pose problems.
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Barriers to Sea Wall Implementation
Although the sea walls are essential for some areas, there are still some barriers and hindrances that may cause difficulties in their implementation. The biggest challenge to seal wall construction is the cost.
To get an effective sea wall design, you will require quality, long-term environmental research about things like wave heights as well as extreme sea levels.
The data required is often unavailable, especially in developing countries, and collecting it can be significantly expensive.
Additionally, since the sea walls endure a great deal of pressure from high wave loadings, their designs must be robust, which may require a large amount of raw material and sophisticated construction methods. All these increase the cost.
Results of a case study by the Pacific Island of Fiji shows that, even when there is the use of local materials, sea walls are still costly to construct.
It consumes a lot of time, money, and labor. Another significant barrier is the lack of expertise. In most cases, the locals lack skills on such projects and therefore, the need to import skilled labor arises.
Also, the lack of specialized machinery, raw materials, and labor can pose a significant challenge to sea wall construction. Having to acquire all the requirements from other cities or countries will increase the total cost.
Conclusion on Sea Wall Advantages and Disadvantages
Sea walls have their good measure of both pros and cons. In this document, we have tackled comprehensively on the sea wall advantages and disadvantages, and I believe that you now have a clear picture of the whole topic.
If you are thinking of a sea wall construction project, whether individual or community, this piece will help guide you through that.
Is this article helpful to you? Do you think sea walls are a good way of preserving our environment? Let us know in the comments below.
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