How can Gabions help protect our coastal areas?

Gabion Seal Wall at Plettenberg Bay by Tuiniqua Engineers.

Brighton beach, Adelaide during the storm

Recent strong winds brought a king tide to low-lying coastal areas causing flooding, damage to jetties and dangerous conditions to Adelaide beaches. Homes and shacks along South Australian beaches have experienced the effects of the one in twenty year storm and we have had enquiries about Gabions and how they can help with coastal protection.

Reports show that climate change, which is increasing sea levels, will adversely impact our coasts. Coastal systems & low-lying areas will be increasingly subject to submergence, coastal flooding & erosion. Beaches, sand dunes and cliffs will continue to erode under increasing sea level(1). Over half the Australian coastline is vulnerable to erosion from rising sea levels, putting not only homes and businesses at risk but also effecting much of Australia’s critical infrastructure such as transport, commercial, defence and tourism industries.

It is not only human infrastructure that is at risk - coastal wetlands, saltmarshes, mudflats, mangroves seagrass beds, rocky shores and sandy beaches are also vulnerable. These provide important habitats for many species, including commercially and recreationally important fish and shellfish(2).

There are many types of sea walls including concrete, brick or block walls, mounded boulders and Gabions. Gabions sea walls have been used in many coastal locations around the world and have several advantages:

  1. As they are flexible and porous they can absorb substantial wave and wind energy, reducing the scour problems that are associated with impermeable walls such as concrete seawalls.

  2. The PVC coated Maccaferri wire mesh baskets we use are one of the few construction materials that can withstand highly corrosive marine environments. They offer up to three times more protection against corrosion than zinc coated wire.

  3. Our Gabions are strong - the double twisted wire and fastening procedure we use ensures that the units act as one extremely strong monolithic structure.

  4. Gabions are aesthetically pleasing and blend in with the coastal environment, which is enhanced when vegetation growth is encouraged.

  5. Gabions provide an excellent habitat for all marine and fresh water species. Spaces between the rocks quickly become filled with silt, which encourages vegetation growth. These spaces can also provide protective habitats for small aquatic creatures to live and lay their eggs etc.

Prospect Contractors have successfully installed Gabions sea walls in marine environments such as at Encounter Lakes, Victor Harbor, the Patawalonga River, Glenelg and at Bar Beach, NSW. We have also installed Gabions in many river locations. Visit our website for more information.

(1) IPCC 5th Assessment Report : Coastal systems and low- lying areas. November 2014

(2) ‘Counting the Costs: Climate change and Coastal Flooding’ Climate Council of Australia 2014

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