Maroochydore nearshore beach nourishment trial

We’re being proactive and exploring other ways to manage our beaches from the risk of coastal erosion in the future. As well as local sand renourishment pumping, nearshore sand nourishment is another method we could use to do this. The results of this trial will help us understand how effective the technique is at Maroochydore.

Project scope

Studies show that there is a limited supply of sand on the Sunshine Coast. Maroochydore beach has been subject to significant erosion events and the addition of new sand from an external source will help to restore sand to the beach and protect the area from erosion.

Nearshore sand nourishment is one method available to help do this. It works by taking sand from another source in the coastal system, such as the spitfire channel, and placing it in the nearshore area off Maroochydore beach.

The nearshore nourishment trial will provide critical evidence to support our understanding of the operational aspects of delivering additional sand to the Sunshine Coast using this sand nourishment method. It will also help us to optimise the ‘value for money’ considerations if we are to use this type of coastal management practice along our coastline in the future.

A technical advisory group was established to highlight any technical issues or concerns that may arise during the trial. Councillors, Queensland Government, Sunshine Coast Council, Surf Lifesaving Queensland, Queensland Police Service and expert engineering consultants were part of the group.

Watch this YouTube video to find out more about council's nearshore beach nourishment trial.

Project update

The nearshore nourishment campaign went ahead in November 2022. The dredge worked 7 days a week, 24 hours per day. Sand placement took place approximately every seven hours about 300m offshore between BA151 – BA155. Please see the placement map (PDF, 410KB) for details.

Project details

The trial was carried out with a trailing suction hopper dredge, which is a certified ocean-going vessel. It can dredge in depth of 25m and can carry (has a hopper capacity of) 2,900m3, which is the equivalent of hundreds of trucks of sand being released with each load.

The dredge came from the Port of Brisbane. The Port of Brisbane Pty Ltd’s Marine Services teams is responsible for safe navigation of the 90km shipping channel. Dredging forms part of these operations and the Port of Brisbane owns a flagship vessel, the TSHD Brisbane, which was used for the nearshore sand nourishment work at Maroochydore.

The dredge took sand from the shipping channel and placed it in its hopper or hull. The sand was released at Maroochydore via “bottom placement” and rainbowing.

Bottom placement operation involved opening the doors at the bottom of the dredge hull above the position required and allowing the sand in the dredge hopper to fall onto the seabed below. Rainbowing involved spraying a sand and water slurry from the deck of the dredge into the nearshore zone.

The sand was placed in a formation to encourage sand migration towards the exposed beach, respectful of the site surf amenity.

The dredge worked for 24-hours a day. It took around seven hours to complete a full cycle which involved taking sand from the navigation channel in Moreton Bay, steaming to Maroochydore, placing the sand offshore from the beach, and then steaming back to the navigational channel.

Approximately 40,000 cubic metres of sand was used for the trial.

Where to from here

We are monitoring:

• the impacts on marine plants and the reef with diver
• the sand movement over time with hydrographic surveys
• the impacts to surf amenity through the University of the Sunshine Coast
• community sentiment on the technique

We will share the outcomes of the trail when results become available.

Overview

The Sunshine Coast local government area has approximately 60 kilometres of coastline, stretching from Caloundra to Peregian Beach.

Our sandy beaches are constantly changing due to natural coastal processes and associated weather patterns.

As a result, our beaches are vulnerable to repeated erosion during storms, increased swells, and other weather events, which can also impact important community assets such as roads, parks, car parks, pathways, playgrounds and amenity blocks.

We need to be proactive and explore other ways to manage our beaches from the risk of coastal erosion in the future.

For example, without enough sand on beaches, such as Maroochydore beach, roads and pathways, parks and buildings behind the beach could be undermined during storms.

Nearshore sand placement is one method available to increase the resilience of beaches from severe erosion caused by storms, swells and weather events.

For more information please view the full list of frequently asked questions (PDF, 202KB).

Contacts

For more information, please contact council.