So, you’re in need of coastal protection…
Historically in Australia there are three main types of acceptable material and methods that have been used for the purpose of preventing or repairing damage caused by coastal erosion. This erosion can be caused by wind or water. Generally, the coastal erosion we experience in Australia is caused by an increase in wave action or an increase in water (sea) height.
All three types of material and methods have been used successfully in the past, however all require special consideration when investigating their implementation.
A process in which sand that has been lost off a beach commonly through long shore drift or wave erosion is replaced from other sources or other beaches. Often the sand recovered is from a spit or natural groyne that has collected the sand which often has come from the affected beach.
Trucking or dredging sand back onto a beach is typically a repetitive process since this method does not remove or provide long term protection from the physical forces causing the erosion.
When coastal infrastructure such as roads and buildings are threatened, often the first idea is to erect a hard structure to form a sea wall, commonly known as a revetment. These are designed to stop the natural movement of sand and contain the sand while creating a buffer to further erosion and preventing the landward migration of an eroding beach.
Rocks can also be utilized when considering a groyne, and there are many examples of these throughout Australia.
The rock used for any coastal application is required to be sourced from a creditable quarry, as there are certain specifications when considering rock supply. Size and density of the rock are two of the critical specifications that need to be adhered to.
Several planning factors come into play when considering a rock structure. These include, and not limited to, public amenity, voids encouraging vermin, reflective nature of the wave action off a hard surface, placing and installation techniques.
The use of geotextile sand containers as coastal protection systems has grown since the first applications in the 1970s. The science behind the implementation of GSCs along with the geosynthetic material used has also matured over this time. GSCs are now seen as an alternative to hard structures providing a medium to long term proposition. Projects throughout Australia that have successfully utilized GSCs include revetments, groynes and artificial reefs.
Generally seen as a soft engineered structure, GSCs provide a useable public amenity along with a structure that has the benefit of absorbing wave action. Sand used to fill the containers can also be collected from a local source.
The success of a coastal erosion solution is wholly dependent upon three factors:
Talk to our team for more advice.