Noosa Main Beach Seawall Design

A seawall is a structure that separates land and water, designed to prevent coastal erosion and other damage from wave action and storm tide inundation.

The existing Noosa Main Beach seawall is over 50 years old and technical reviews show the wall is degrading at a rate of three percent per year due to wear and tear and less-than-ideal rock choice. The movement of the rocks over time has also significantly reduced the resilience of the Noosa Main Beach foreshore.

Historical image of the Main Beach seawall courtesy of Heritage Noosa.

Rock naturally degrades over time depending on the type of rock and the environment. The rocks in the Noosa Main Beach seawall started at 2.75 tonnes each but now weigh an average of 600kg - less than a quarter of their original weight. The use of basalt as the predominate rock has been a factor in the wall’s breakdown. 

Other key issues include:

• wave pounding – every wave creates tiny chips and cracks that eventually break the rock apart.
• salt water attack – salt water crystals form and widen existing cracks
• rock-on-rock grinding
• chemical breakdown from salt water reacting with iron-rich minerals in basalt.

Seawalls are designed to absorb and deflect wave energy to protect the coastline. Smaller, smoother rocks cannot absorb wave energy as well as larger, angular ones.

The deterioration of the existing seawall is a substantial risk during future severe weather events so early intervention is vital. 

Sand is important to the resilience of the beach, and the Sand Recycling System has a key role in maintaining the beach and maintaining the structural integrity of the sea wall.

Council is looking at options to enhance, not replace, the current system, with the aim to maximise how we use what is already in place.

The scope of this project is limited to redesigning the seawall to improve resilience.

Issues outside the scope include car parking and traffic management. Other areas of the beach, such as the groynes, are also not part of this project. 

It is anticipated the final design will be completed in early 2026.

Council wants to prevent the catastrophic impacts to the community that a major disaster event can cause.

Council has learned from other coastal locations that proactive action to coast seawalls before failure occurs will minimise these impacts, plus allow for the planning of the best long-term option.

Replacing the seawall ahead of a major disaster event will also have cost savings, with emergency repairs being 5 to 10 times more expensive than planned maintenance. 

Noosa’s Main Beach is a drawcard for locals and tourists alike. Construction would ideally be timed to avoid the peak summer period.

Timing for construction will depend on Council securing funds from the Australian and Queensland governments after design is complete.

Behind the scenes there is work already underway to make a submission in early 2026 with a view to construct in 2027.

The existing seawall alignment runs along the Main Beach Boardwalk, with the seawall largely invisible beneath the sand. The design will consider this area along with the adjoining section of beach.