The thought of owning a seawall is so satisfying that owning one is like a slice of heaven to the owner. Seawalls serve as a protection for your home or business and can be termed as a coastal defense while increasing the value of your property. Adding a seawall to your shoreline is a great way to protect and enhance your waterfront property.
So, let’s get to it, what is a seawall?
A seawall is a marine construction structure that protects against coastal flooding, erosion, and waves. Seawalls simply put are essentially a structural boundary between the sea and land. Seawalls can also be seen as structures made of concrete, masonry or sheet piles, built parallel to the shore at the transition between the beach and the mainland to protect the inland area against wave action and prevent coastal erosion.
The height of a seawall will at least cover the difference between the beach level and the mainland, though commonly seawalls are built higher to protect the land against wave overtopping. Seawalls are also used to stabilize eroding cliffs and protect coastal roads not forgetting settlements. The crest of the wall often extends into a stone covered part that may 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 the case of narrow or steep beaches, where a typical breakwater is either too large or not economical.
Some benefits of a seawall are seen in the following:
- Protects Property: flooding is mostly caused by the increase in rain resulting in increased water levels. Flooding can come on very fast and create a tremendous amount of property damage. Installing a seawall to your property means a significantly higher amount of protection.
- Protects Land from Erosion: over time, waves that are in large bodies of water push up against the land. This result in the break-up of land which goes back into the ocean, thus less land and more sea. If you own waterfront property, you are aware of just how problematic this may be. By installing a seawall, you’d have fewer worries and more land to enjoy as the line between your area and the shore stays in place reflecting the waves to the sea.
- Protects the Environment: having a seawall built is like the stitch in time that saves nine. You can be assured that your surrounding and whatever is in it are safe from the effects of flooding as well as wave action and land erosion.
- Provides Recreation: seawalls do more than protect, they can serve as space for biking, exercising, and walking. Sightseeing is safer for visitors since the seawall provides protection when the water levels and waves are high.
- Cost Effective: seawalls are a cost-effective means of protecting your waterfront property and environment since they do not consume much space and are more affordable compared to other forms of sea/land defenses. The immediate cost of setting up a seawall is worth it.
- Lasts a Long Time: do you know that seawalls can last decades? Many gulf coast seawalls according to records are over a hundred years from the time of construction and still serve well. With proper maintenance, seawalls can protect your waterfront property for a very long time.
Top factors when constructing a seawall include:
- Location and accessibility
- Weather concerns
- Size of seawall
- Cost (and budget)
- Marine conditions in your region
Building a seawall should be the top priority if you have your waterfront property in mind. It is a smart investment. Seawalls are impressive structures that serve well for recreation and more importantly protection. Having a seawall installed is the way to go as a waterfront property owner.
TYPES OF SEAWALLS
Seawall as a hard engineering solution to dangerous sea waves are of different types which are built according to the varying physical & natural forces they are designed to combat & repel. The type of seawall constructed usually depends on specific aspects such as wave patterns, climate or weather conditions, erosion processes and location. Choosing the most suitable type of seawall is therefore based on the purpose it is built to serve and the conditions attributed to a specific location.
The different types of seawall work by either dissipating or diverting incoming waves back to the sea there by obstructing the effect it’s energy and resulting impact would have had in causing erosion and damage to infrastructure and properties.
Although the functions of these man made protective sea barriers are associated with negative effects on the environment such as disruption of normal sediment movement, destruction of ecological biodiversity & obstruction of transport routes, softer engineering alternatives such as the replenishment of beaches & construction of coral reels have been proposed and sometimes adopted, which lessens the cost of maintenance and level of beach depletion.
The different types of seawalls include:
- Curved Seawall: Curved Seawalls are designed to withstand, divert and dissipate high sea waves approaching inland thus reducing its overall effect and resulting impact such wave would have had by repelling the incoming waves back to the sea. These type of sea walls are built in a curve like manner to mimick the shape of an incoming sea wave with sheet piles as a supporting base for the structures foundation. This strategic curved structure serves a dual function of preventing the sea wave from going above the wall and also prevents the loss of supporting materials placed beneath the walls base due to scouring waves, overtopping water levels and storm drainage.
- Stepped Face Seawall: Stepped Face Seawalls are built to oppose & deflect moderate sea waves action effects. This type of seawall is constructed using reinforced concrete sheet piles with tongue & groove joint features. Spaces in between the sheet piles are made & filled with Grout (for a sand proof cut off structure) or an installed geotextile fiber placed behind the sheet piles to form a close fitted sand barrier.
- Vertical Seawall: Vertical Seawalls are constructed in areas where the coastline are exposed to the elements on a wide scale. These vertical structures reflect the waves energy, deflecting it away from the coast line & back into the sea. Vertical Seawalls can experience short term damages due to erosion at the walls base as a result of non breaking standing wave patterns that form during intense sea storms, resulting in a stationary clapotic wave which moves up & down instead of traveling in a horizontal direction.
- Rubble Mound Seawall: Rubble Mound Seawalls are designed and put in place to resist lesser strong wave actions. This type of seawalls involve the use of revetments or Ripraps which are cost effective alternatives in areas with lower energy erosional processes or levels as it might be cheaper and easier to construct. The rubble mound seawalls slope and loose material content ensures maximum dissemination of incoming wave energy making it the most suitable seawall as its slopy nature and mechanism of action leads to the retention of beaches.
- Steel Sheet Pile Seawall: The steel sheet pile seawall is constructed from steel sheets that are interlocked and secured deep into the coastal line beds with a pile of earth behind the wall. The pile of earth provides additional reinforcements due to it’s heavy weight and doubles up in draining excess water through openings within the wall. This steel sheet pile seawalls are mostly used in areas that are not severely hit with intense or high level sea waves.
Other type of seawalls include:
– Gravity Seawall.
– Concrete Block Seawall.
HOW TO PROPERLY CARE FOR YOUR SEAWALL
Proper maintenance and frequent replacement of seawalls is a necessity to ensure their effective function. Cracks, breaks or depletion of a seawalls underground support such as boulders & gravels can put the entire structure at risk if not properly managed, taken care of or corrected. Below are some of the ways to properly take care of your seawalls
- Frequent checks for serious cracks, wide holes and breaks in strategic points on your sea wall such as in the middle and at the edges to prevent flowing water from eroding the soil and sand from within and beneath the wall.
- The periodic replacement of the walls underground support such as with gravels, boulders and dense soil should be done to prevent complete depletion by water waves.
- Regular inspection especially after heavy storms to ensure the materials used in constructing your seawalls such as composite, aluminium or steel have no visible faults that could make the seawalls vulnerable to collapse.
- Employ the services of divers to inspect the sediments around your seawall and determine if it’s current thickness is sufficient enough to buffer its base.
- If you have a rip-rap seawall in place it is important to check for any stones that may be out of place and need adjustment or immediate replacement.
- Weeds and certain form of plant growth could subject your seawall to vulnerability as their roots may gradually widen cracks in a concrete seawall and allow water to seep in and build up pressure overtime within the structure. Therefore, it is important to remove weed or plant growths that are not part of the structures strategic or aesthetic design.
- Waterproofing the materials used in constructing seawalls with double coatings, multi layer of plastering or paint is also another method of taking care of your seawall and preventing excessive weathering or damage due to various elements it is exposed to.
Overview on Seawalls and conclusion
Seawall’s are artificial man made structures made out of concrete, composite, vinyl, steel etc constructed in a vertical or parallel manner near the shoreline to act as a coastal shield and the first point of impact against dangerous sea processes such as hurricanes, tsunamis, increase in sea tides etc. Seawalls serve two basic important functions which include: -providing protection to residential & commercial building’s, private properties and public infrastructure located close to the coast from erosion, storms & flooding. -taming any intense sea activity close to the inland such as rising tides & high to medium scale sea waves.
These shoreline shields are constantly interacting with the sea and therefore exposed to a wide range of denudation forces and elements subjecting them to wear & tear. The regular maintenance and proper care of your seawall is required to mitigate against destruction, ensure the structure remains intact and assure longevity since they are an important & essential part of waterfront structures due to the remarkable role they play.
Frequently Asked Questions about seawalls, revetments and bulkheads.
What is a seawall or retaining wall?
A seawall (or sea wall) is a form of coastal defense constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a sea wall is to protect areas of human habitation, conservation and leisure activities from the action of tides, waves, or tsunamis.
How often do seawalls need replacing?
Properly designed and well-constructed seawalls have a life expectancy of 30 – 50 years, if properly maintained. For effective, well-built seawalls, in almost cases, it is more cost effective to repair a current seawall, rather than replace it.
What is a revetment wall?
Revetment walls are permanent structures designed to prevent subsidence that commonly occurs adjacent to all waterways and the ocean. By definition, a revetment structure is a protective covering on an embankment of earth designed to maintain the slope or to protect it from erosion.
What is the difference between Seawall vs. bulkhead?
Many people will refer to all vertical shoreline structures as “seawalls,” but there is a difference between a seawall and a bulkhead. A Seawall provides shoreline protection from waves but also retains soil. A bulkhead is a vertical shoreline stabilization structure that primarily retains soil, and provides protection from waves. The “rule of thumb” in bulkhead design is to account for wave impacts.