WHILE experts are investigating ways to prevent sand being eroded from Portsea beach, members of Nepean Ratepayers Association say only two of six options will work.
Association president Colin Watson says the Department of Environment, Land, Water & Planning is “fully aware of this position” but has been told by the Environment Minister Lisa Neville to have all options examined “in a robust manner before any final decisions are made”.
The company hired to investigate ways of protecting the beach, Advisian of Worley Parsons, handed in a report in January on wave processes impacting on the front beach at Portsea.
Environmentalists have blamed the loss of the beach and increased swells on deepening of Port Phillip shipping channels.
The six options to rectify the beach were the result of Advisian’s earlier report which – through physical and computer modelling – found that fluctuations in the levels of sediment on the Quarantine Bank and seabed were capable of changing the direction and power of waves.
The report – Portsea Front Beach Wave Modelling and Monitoring Investigation – found seabed levels could change by up to five metres within two years.
The consultants also found that wave energy “could be attributed also to changes in meteorological conditions. Nevertheless, as the rate and direction of littoral drift transport and, hence, beach alignment are related directly to nearshore wave height and direction, future changes in beach alignment at Portsea Front Beach can be expected,” the report stated.
The report said increased wave energy, particularly during storms, has led to eroded sand dunes.
Advisian recommended ongoing monitoring of the beach and Quarantine Bank and profiling of Weeroona Bay, where sand was dumped on its eastern end.
Advisian has until the end of September to report on the following six options for fixing the sand problems at Portsea:
- Dredging to shape the seabed.
- Building a breakwater on the seaward side of Portsea pier.
- Installing groynes or creating an “artificial headland” on the beach east of Portsea pier.
- Replacing the sandbag wall with a rock seawall.
- Adding sand to the beach in combination with the first four options.
- Removing the seawall to see if the beach recovers or gets worse.
“At this stage I believe [Nepean Ratepayers Association] will continue to work with the department and keep reinforcing to them that nothing less than stopping the wave swell will be accepted by the community, as only the first two options will actually divert the wave energy that has been now existent since early 2009,” Mr Watson said.
He was “very happy” with the action being taken but “my only concern was that we still have no guarantee that irrespective of cost’s the funds will be found by the government to fund the favoured option”.
First published in the Southern Peninsula News – 10 May 2016
