The problem with sea walls is they reflect the energy of the waves back to the sea. This means that the waves remain powerful. Over time the wall and surrounding coastline may begin to erode causing increased erosion in adjacent areas of the beach 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.
According to The Nature Conservancy research Oyster reefs save communities $85,000 per year per hectare when used in place of artificial breakwaters.It’s no secret nature always has the perfect solution when it comes to protecting the land and us so why are we building sea walls and not investing more in natural solutions such as oyster reefs and sand dune restoration?
This year several projects have sprung up around eco engineering to protect coastal assets and they take time and money, but surely this investment long term will save the costly maintenance fees it takes to maintain expensive seawalls. Per linear metre sea walls cost upward of $15,000 not including the cost of labour and maintenance over it’s indefinite lifetime.
In Sydney 50% of the foreshore in Sydney has been artificially constructed resulting in significant loss of our coastal habitats. Over 90% of oyster reef habitat has been lost Australia wide since pre-European settlement making this particular habitat one of the most endangered we have. Oyster reefs offer a suite of eco – system service ranging from habitat for young fish to a coastal erosion solution as they naturally absorb wave energy from boats passing by and in turn protecting the coast from erosion.
We believe restoring oyster reefs is fantastic for coastal regions and the opportunity to scale up is huge. Using more holistic approaches such as oyster reef restoration, sand dune revival and mangrove protection stand to make a much more permanent and natural defence to our coastal assets than ill thought out concrete structures.
Check out the oyster reef restoration project below to learn more.