How effective are seawalls?
While seawalls can be effective at protecting the shore from wave erosion in the short-term, in the long-term they create more issues than they solve.
What are the disadvantages of a seawall?
Seawalls block the absorption of wave energy. This means that when a wave hits a seawall — instead of natural vegetation or sand/soil — the energy is deflected rather than absorbed. The energy does not just disappear, it is redirected elsewhere.
Wave energy deflected by a seawall is redirected in two possible ways. The first is downward. This creates an event known as “scouring.” When wave energy is deflected downward towards the lake or sea bottom, it scoops out the soil. Eventually, scouring causes habitat loss. It also renders the seawall completely ineffective because, when the water becomes deeper, waves are able to undercut the seawall. Long-term effects include more algae and cloudy water.
The second way wave energy is redirected after hitting a seawall is called “wave flanking.” Wave flanking is when the energy is directed sideways. The energy moves towards neighboring properties and homes where it causes accelerated erosion. This in turn creates a domino effect. When one homeowner decides to install a seawall, they are essentially forcing their neighbors to do the same until everyone in the area is forced to install an expensive and mostly ineffective unnatural barrier. The lake or sea suffers and the seawall eventually fails.
In order to ensure you are being responsible with your seawall installation, consult the U.S. Army Corps of Engineers as well as a professional team before starting your project. The U.S Army Corps of Engineers has plenty of resources and documentation that can help you decide which type of shoreline protection will be most beneficial to you and least harmful to neighbors and the environment.
How long does a seawall last?
Depending on the type of seawall, the area where it’s installed, and the materials used, seawalls can last between 20 and 50 years. If the seawall is not maintained, however, it will fail much sooner.
TrapBag® has a life of at least five years, and has been proven to withstand whatever mother nature brings to bear from mudslides and floods to coastal storms and intense wave action, our bags have seen it all and continued on unimpressed. Whether you’re looking for short-term flood protection or long-term erosion control TrapBag® is a strong option that will last.