EMU – Erosion Mitigation Units

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  • 2023

  • Engineering

Designed By:

  • REEF DESIGN LAB
  • Alex Goad

Commissioned By:

City of Greater Geelong

Designed In:

Australia

EMU (erosion mitigation units) are a series of artificial reef modules that form a permeable barrier designed to reduce the height and energy of waves. This provides coastal erosion protection during storm surges, supporting sand accretion while also providing intertidal habitat for native oysters, seagrass, fish, and marine invertebrates.


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Image: Photo by Alex Goad
Image: Photo by Marcia Riederer
Image: Photo by Alex Goad
Image: Photo by Alex Goad
Image: Photo by Alex Goad
Image: Photo by Alex Goad
Image: Photo by Alex Goad
Image: Photo by Alex Goad
  • CHALLENGE
  • SOLUTION
  • IMPACT
  • MORE
  • The City of Greater Geelong required a series of cost effective reef modules that would attenuate wave energy while creating habitat for native species and a snorkelling attraction for local residents. Standard coastal protection approaches are often seen as unsightly and can alter ecological and physical processes. Therefore the solution needed to be sympathetic to the natural environment and designed to blend in harmoniously over time. The brief also required that the units be easy to install and made from low energy eco friendly materials that would withstand the harsh marine conditions.

  • EMU’s are a series of 2 metre wide modules that have an optimised geometry creating a more complex surface which led to greater wave dissipation. This allowed us to create an organic sculptural aesthetic that was ideal for including the complex habitat niches required for marine colonisation. When positioned together the modules create an undulating effect allowing snorkelers to safely glide between the system. Manufactured from a reusable moulding system and cast in a low energy concrete mixture with recycled shell and integrated lifters the modules are easily installed in the marine environment using standard low impact techniques.

  • As climate change drives extreme weather events there is a global movement away from hard coastal engineering towards softer nature based approaches. Through ecologically inclusive design our solution is redefining what these approaches can look like and how they can work to benefit the local community and the environment. The installation for Geelong has already become a safe and accessible location for school tours where students can learn about nature based solutions to coastal erosion and how habitat design can be included in marine structures.

  • We’ve taken great care in crafting a range of habitat and textures within each module, from the smallest sandblasted crevice that allows mussels and oyster to colonise to large caves that give Banjo Rays a place to rest. The modules also include rock pools that retain water at low tide providing functional intertidal habitat that birds love to feed on.