Posted 14/11/10

Latest Blue Wedges Newsletter: 

Report On Portsea Beach (or what's left of it)

We haven’t reported in for some time, so there’s plenty to tell. 

It seems that as the State election and summer approaches, and as Portsea beach just kept looking worse and worse for months and months, that government has been desperate to spin the line that the recent and sudden erosion damage at Portsea has got nothing to do with their dredging project.Whilst everyone accepts that beaches do change and that sand tends to come and go with the seasons and storms; dive operators and other users of the pier now regularly find it unsafe for boating, and locals are adamant that there has never been anything as sudden and dramatic as what has occurred at Portsea in the last 12 months. Until then it had been a safe and stable beach since time immemorial.

All this made Adam Morton's Age article of Saturday 16th October 'Between denial and the deep blue (rising) sea' [1] particularly relevant.

Morton starts with a discussion of the Bruun Rule – a concept Blue Wedges has been rattling on about for some years. Broadly, the Bruun Rule states that for every unit that water rises vertically it can spread (inundate) 50 to 100 times that distance on flat land.

Whilst the Bruun Rule is only a general rule, it is nevertheless an immutable law of nature that as water rises it spreads – to various degrees deepening on the slope of the land it meets. Despite this, the government appointed Office of Environmental Monitor (OEM) and the Port of Melbourne Corporation (PoMC) steadfastly say that there is no relationship between increased water levels and the erosion currently occurring at various places around the Bay[2], especially Portsea - despite the acknowledged increase in water levels post dredging in the OEM’s latest quarterly report[3].

Sir Isaac Newton worked it out 350 years ago that for every action there is an equal and opposite reaction, so how can the OEM and PoMC keep getting away with claims that there has been no reaction by Mother Nature to the deliberate action of enlarging the Entrance? So - what OEM should be asked to prove is how the increased water levels even they have admitted to have NOT added to the erosion damage and the dramatic increase in ocean swell which is so obvious at Portsea.

The story:

By December 2009, Council had already removed several mature trees that had suddenly slumped into the water.

Council tree removal works Portsea beach December 2009 

By Easter 2010, several metres of sand had been lost from the beach and the line of mature vegetation which had withstood decades of storms continued to fall into the sea.

Portsea beach March 2010 just before the worst set in. Damaged remaining tree line evident

© J. Warfe

If weather and/or sea conditions had not changed, it made no sense that these trees were just suddenly giving up and that so much sand could just disappear so dramatically. So, it's noteworthy that an analysis of weather patterns over the last ten years recently done by the Port Phillip BayKeeper http://www.bay-keeper.com  suggest that there has not been any extraordinary weather patterns which could explain these sudden and dramatic changes.

Around Easter 2010, severe damage to the underpinning of the Portsea pier also occurred. See image below:

Big hole. Watch your step! 

30 April 2010 Portsea Pier ©Karl Graddy

  2 May 2010 – but not for long- these remaining trees soon succumbed.

L. Salter

During informal discussions with the OEM in May, they suggested that storms have always contributed to erosion damage, citing one such storm reported in The Argus. However all such reports from that time that we could find indicate those storms were from the South West, consistent with the Argus reports of impact in North of the Bay. There was no mention of damage to southerly beaches such as Portsea. (Portsea is really only vulnerable in strong northerlies). See for example: Argus 1934.

Back in Portsea, by late June/July a large sandbag sausage and some rocks were dumped around the base of the pier and a sandbag wall was constructed towards the back of the beach. See image below:

Sandbag sausage to hold back the sea?

1 July 2010

 By August, as erosion damage continued these smaller sandbags were “removed” and tonnes of bluestone boulders were dumped on the beach. Workers told locals that the massive rock wall was temporary, required to protect workers and their machinery as they undertook further excavations on the beach.

The Leader August 31^st 2010

The sandbags and white geotextile lining fabric were flung over onto the rock wall were still there as an eyesore when we last checked last week. See image below.

6^th October 2010

On 4^th August, in response to community concerns, DSE and OEM met with various “interested” locals in Portsea. Blue Wedges was not invited, nor was the Dive Industry, the Port Phillip Baykeeper, nor various other entities that could be described as stakeholders. We were told that PoMC CEO Stephen Bradford attended - interesting given that the OEM and PoMC are certain that there is no relationship between PoMC’s dredging project and beach erosion[4]. 

5^th October 2010 A. Lewins

On 12^th October, a similar meeting was hosted, although again key stakeholders were not advised of the meeting. You’d have to wonder why the meetings, supposedly to update the community, were so poorly advertised. DSE led the meeting. This time, neither PoMC nor OEM was there.

DSE stated they were there to talk about their area of expertise, being “protection of coastal assets”. Anyone who queried a relationship between dredging and beach erosion were told that wasn’t something DSE could comment on and were referred to the OEM – who weren’t there.

DSE advised that the first round of sandbagging and dumping of rocks in July was not a “failure” (as someone in the audience had suggested), it was an experiment to work out how best to fix the problem. When asked if a study of wave diffraction and refraction had been undertaken to help ascertain why the damage might be occurring, DSE said they were not sure, and that question should be referred to the OEM. The questioner persisted to ask how DSE could plan how to fix the problem if they didn’t understand the cause, and that $2 million of public funds might be wasted on a bandaid solution. Pretty good question we reckon!

DSE went on to say that the project is ahead of schedule, it was the best possible solution – not a bandaid - and that they are very proud of their work.

17^th October 2010. Another two layers of sandbags yet to be installed.

DSE advised on 12^th October that it's likely that several layers of sandbags will always be visible at Portsea beach. We'll be interested to see how beach goers react to sitting on a wall of sandbags, (surely it will be mightily uncomfortable?) and how long they last. DSE claim the bags have a lifespan of 20 years - after which they will require replacing.

A recent update from DSE (29/10) advises that the works are almost finished, (just in time for the election hey!) and that a sand ramp will be constructed at each end of the massive sandbag wall for eventual access to the beach. The Mornington Peninsula Shire has also been asked to stump up $80,000 for revegetation, paths and access works. We understand the Shire recently agreed to contribute $40,000 towards the works. Poor old ratepayers! 

Unintended consequences?

Locals are also adamant that nearby Shelley Beach around Point Franklin to the East is now accreting. A recent visit there by the Port Phillip BayKeeper found masses of the white geotextile fabric, presumably from Portsea beach, has ended up on Shelley Beach. Presumably some of the material that has been discarded on the rock wall at Portsea pier has broken up and is now littering Shelley Beach.

A consequence of the project not to be so very proud of perhaps? See image below:

Just a small piece of the masses of geotextile fabric now littering Shelley Beach Portsea. 

17th October 2010

Role of the Office of Environmental Monitor

Given that the OEM has adopted the PoMC’s Environmental Management Plan as its own “Rule book” you’d have to ask how independent the Office is, or is it a fig leaf of propriety and an apologist for government.

OEM’s latest report[5] also refers to the Foreshore Erosion Board in what appears to be an attempt to imply that it’s all happened before. We understand this Board was set up in response to severe storms in the Bay and its 1936 Report recommended an extensive program of sea wall construction. Argus articles at the time refer to the Report and mention damage to and recommendations for various beaches around the Bay including Dromana, Tootgarook and Sorrento – but not Portsea. For example:  Argus March 5th 1937. Many miles of masonry sea walls have since been constructed around the Bay. Of course it’s now pretty well accepted that sea walls were a mistake as they protect the land, but cause loss of beach in front of them. None have been built now for many years.

Decisions made in ignorance of or indifference to the natural coastal processes or perhaps for expediency date back many years. Those decisions have reached forward through the years - often with disastrous consequences. It seems we might still be making those same mistakes – except this time we can’t use ignorance as our excuse - surely?

Cheers,

Blue Wedges Editor

[1] See: Morton’s article at: http://www.theage.com.au/environment/climate-change/between-denial-and-the-deep-blue-rising-sea-20101015-16nkq.html

[2] OEM quarterly Report Page 8: “All the evidence so far is consistent with the limited effects that were predicted and these limited effects were not considered sufficient to cause the beach erosion seen in the Bay”. 

[3] OEM quarterly Report Page 8: “It was predicted that after the Entrance was deepened, tides within the Bay would increase by around 10mm. Fifteen months of scientific data confirms that high tides have increased by 10mm and low tides have decreased by a similar amount”. 

[4] Various letters to local papers expressing concern about a link between erosion and dredging have usually elicited responses from PoMC CEO Mr. Bradford to state that PoMC’s rigorous science has discounted the possibility of a relationship between dredging and damage to Portsea beach.

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