thumb|Channel in 2015

The Gold Coast Seaway or Southport Seaway is the main navigation entrance from the Pacific Ocean into the Gold Coast Broadwater and southern Moreton Bay and is one of Australia's most significant coastal engineering projects. It is located at the northern end of the Southport Spit where the Nerang River enters the Pacific Ocean via the Broadwater. The channel was constructed between 1984 and 1986, primarily to facilitate the safe passage of sea-faring vessels. The passage was previously known as the Southport Bar. The mouth of the Nerang River was once located further south in Broadbeach. The main driving force for this movement is the northward drift of sand along the coast.

Before the bypass system was implemented the mouth of the Nerang River moved northwards at a rate of 60 metres per year. This northward drift was responsible for the unstable and shifting conditions of the bar, which made crossing it hazardous for small boats.

Design

Two rock walls to stabilise the position of the entrance were constructed. One million tonnes of imported rock was used. The mean depth is 11 m During outgoing tides, excess treated wastewater from four sewage treatment plants is released into the channel.

Gold Coast Sand Bypass System

Research conducted by the government indicated the quantity of sand movement necessitated a solution that operated perpetually. The Gold Coast Shoreline Management Plan is reviewing this practice and examining the concept of Island welding to determine if 85% of the sand (80,000 cubic metres per year) can be sustainably recycled to Surfers Paradise.

The bypass system uses ten pumps located along the jetty. It is managed by the Gold Coast Waterways Authority.

See also

  • Southport Spit

References

  • Seaway Surf Cameras
  • Moreton Bay Marine Park