Nearshore Nourishment Trial outcome summary

Following a review of the data, Sunshine Coast Council has concluded that the Maroochydore Nearshore Nourishment Trail (that took place in late-2022) did produce an increase in sand on the beach.

It found the technique could potentially be used on a larger scale for future nourishment campaigns along Maroochydore Beach and in other coastal locations.

Here is a summary of the findings or for more information read the Maroochydore Beach Nearshore Nourishment outcomes report.

Beach surveys

Hydrographic surveys and cameras monitored sand movement since the trial finished. Monthly topographic (upper beach) survey results show there was a net increase of 34,170m3 of sand in the upper beach profile along Maroochydore Beach from December 2022 to April 2023.

Surf amenity

A study via UniSC has closely watched the impacts to surf amenity and the results were inconclusive – neither positive nor negative.

Reef impacts

More will be known about any possible impacts on marine plans and the reef when divers complete their next marine plant survey in November 2023 (as per the permit conditions 2201-27063 SDA).

Safety

Safety measures were appropriate for the scale of works (closing of the beach and water), no incidents or near misses occurred during the operational phase of the trial.

Location

Using Maroochydore Beach for this project provided an opportunity to test the technique in a more challenging environment. Maroochydore Beach was also chosen due to a lack of sand. Maroochydore Beach was a challenging beach to undertake the trial at as it is not a linear beach. It is an embankment with rocky headlands and rivers at its boundaries. Sand nourishment using nearshore nourishment is hard to model along this beach – which is why a trial was needed.

Straight stretches of beaches (Kawana – Moffat, Yaroomba – Maroochy Northshore) are a simpler setting to model and this technique will have a high likelihood of success if used at these types of locations.

Community sentiment

The small number of responses suggests that the majority of the community did not have major concerns with the project. Council confirmed that there were no customer requests created during the operational phase of the project, suggesting that beach closures were generally accepted.

Considerations for future campaigns

• Placement of sand to use the rainbow technique first and then place the sand via bottom placement behind the rainbowing to ensure sand is placed closer to the shoreline to allow it to migrate efficiently into the upper beach.
• The location of nourishment was appropriate and the buffer to the reef habitat should not be reduced to ensure no lasting impacts on reef habitats as a small portion of sand migrated south during the monitoring period.
• Extend the surf amenity survey for any future campaigns and include baseline data (pre-surf condition assessment).
• Cost efficiencies would improve if sand could be sourced closer to Sunshine Coast (directly offshore). Council should investigate a local offshore sand source and approvals required to access this. Refer to the sand sourcing study for more information.