Groynes have been nominated to save the beaches at Apollo Bay .
The whole idea of sustainable development is based on the necessity for appropriate development and solutions that suit the circumstance's. This contrasts with the common contrary unsustainable and wasteful notion that a solution is in the name alone .
Not only are groynes not the solution for everywhere there, they have to be well located to work anywhere .
Sand supply is currently very inadequate (and patchy) to the beaches and dune systems around Apollo Bay township, The lack of bed load movement through the Barham River system in recent times has limited beach dune rejuvenation on the southern beach to Marengo .Groynes can't be expected to work on the southern beach because of the structures there .
The crisis site in the town requires much more rigorous investigation and design with nature ( see below) to support the retention of the beach dune system there.
CONTEXT
Groynes are useful in some areas ( especially where sand supply is good like to Point Bunbury and Wild Dog ). They are not " the answer" as some are suggesting for the area generally . I don't believe groynes would ever work on the southern beach, but that's not for now
Groynes which don't fill up with sand quickly and cause it to naturally stay there ( the ones proposed in the crisis area ) can be expected to modify the environment from a beach dune system to a situation where rock walls and other non beach type features have to be constructed.
Does anyone expect the government to keep topping up the supply to an artificially raised sand bed stall forever ?And what happens to the beach and dune amenity and the pile of loose sand when it dries out / ?
Before we commit to permanently changing /ruining the beach dune system in the crisis area, i am calling for a more thorough review of the degrading processes in that area so we might retain the full beach dune system for as long as possible .
Maybe we should move and change some of our stuff rather than expect the natural system to give way ?
Southern Beach Marengo area
Lack of sand supply to the dune beach systems south of the Barham River is a recurring reality . As there is no replenishment from the north , the best we can hope for is major river flows , floods and bed loads in the Barham river to place sand in the intertidal zone.
Town beach Crisis area 2/ 70 metre rock groynes proposed to be built in the township area before Easter
There are a number of reasons why the proposed groynes in the town cannot be expected to deal adequately with beach erosion and access problems in the Apollo Bay township area. The principal limitations in the area are the ongoing problems of sand supply , the ongoing impact of inappropriate development practice.( which can be reduced ) and the non resolution of changed access, amenity and beach and dune performance ( the best appropriate vegetation is not stated )
The desirability/natural pattern of sand flowing north in the intertidal zone to rejuvenate the northern beaches has been interrupted badly by construction of the harbor. While much of the sand that would have helped rejuvenate township beaches is lost to the ocean off the end of the Harbor wall , care is required to retain and make use of the sand accumulated beyond and behind it .
Before we abandon the idea of helping to support and build the damaged beach ridge system ( its complete loss is implied in the recent proposal document), we need to face the fact that the particular beach dune system we inherited, is the best one to maintain the natural asset so widely valued. Before any harsh measures to reduce long shore drift are imposed, we need to be convinced that all other techniques to reduce erosion of the system have been taken ( they haven't been ) .
A full big picture review of the existing erosion risks and the possibilities to reduce it needs to be undertaken .
Existing risks --many of which can be lowered
The increased curvature of the beach behind the harbor can put more pressure on the "Crisis " section for long shore drift . This is just one of the many , if small , ongoing risks that needs to be assessed if the dune system is to survive the mass of inappropriate interference
( eg big pipes ,walk tracks, trees and parking ) that has continued since then in that section .Urgent attention to reducing development impacts needs to be thoroughly examined .
Council should have by now have processed a full survey of manmade structures ( invert levels pipe bridge and storage sizes /levels with a view of preparing for the future and future uses and land use changes ( The job of the planning department) .
Existing possibilities
There is a considerable amount of sand now accumulated behind the harbor which could be carefully used to support the beach ridge system in the crisis area, The best way to do that is not a top down approach as has been tried in recent years,( by trying to create a dune by dumping loose sand ) but by using a bottom up approach ( maybe dredging sand into the intertidal zone).. Nature maybe slower, but it is usually more efficient .
Inevitably there will be times when the dune system fails as the existing landforms, the swale and the flood plains in both the Barham River and the Milford Creek area show.
The severe erosion of the dune system between Cawood Street and Marriners' Lookout Road ( hereinafter called the Crisis section ) is related to the failure of the managing authorities to properly manage the ongoing erosion and, in particular, the Council’s failure to properly manage storm water moving into the sea in that area and land use impacts ; there is also the Coastal authorities failure to manage and protect dune integrity ( inappropriate fencing , access , vegetation, parking , rocks ) .
Groynes are not going to solve the greater problem of sand supply unless the problem of sand supply is directly and well addressed by a design with nature approach . (It’s not clear from the latest report by GHD what efficient , natural and other measures, might be applied to address this.)
While groynes may assist in the problem of longshore drift the extent and impact of that drift is not demonstrated in the current reform, to be relevant in the critical control section. The impetus for the new solution for a new solution seems to come from the way the old Wild dog groyne has been engulfed. The apparent effectiveness of a groyne in a rich sand supply area, like that near Wild Dog Creek, is not a sufficient basis to adopt it in the township area. The circumstances for sand accumulation and effective and lasting dune rebuilding need to be properly understood. .
The major basis on which sand can be supplied and retained ( equally important ) in the crisis area needs to be established before any new works created or approaches tried.
The Big Picture Review ( not all elements maybe listed )
Before any more rocks are placed on the beach north of Apollo Bay, planning agencies need to more closely examine the ways in which they can continue to work with the beach-dune system. .They also need to review what all the works like rock sand tree, carpark and access and culvert placement have and haven’t done to increase the erosion .
Such a report would show:
- What have the shire have done to accurately survey manmade features and their impact on the natural features. Was Tony Miners group involved in this ?
- What does the survey suggests to the Planning Department about what should be the proper placement and size of roads houses , drainage , vegetation storm water storage , parking and access for the future
- What changes to stormwater and structural landscape elements, like the bridges culverts fences, rocks , groynes storage area, invert levels can do to reduce the erosion problems .
- What might be the best way to unnaturally move sand ; and from where to where (eg should dredging be used to bring sand into the intertidal zone ( from the ocean floor or from behind the harbor site , for example ) Dunes and beaches are best built from the bottom up
- How will sand movement by wind be used to build and restore dune beach systems
- Sustainable long term location of the Great Ocean Road ( in principle )
- Sustainable access (the boardwalk as shown in GHD report is not sustainable, ) cross dune and road and drainage planning must all better consider wind wave and sand movement patterns required to maintain the use.
- Long term land acquisitions and changes of land use in the crisis area ( eg whole swale area ) , as long recommended,
- Sound Parking (the current parking on the foreshore side of the beach side of the road is unsustainable)
- The proper vegetation for the area (some of the featured trees are just not sustainable for protecting the dune system.
- Measurements of sand movement at low and high tides, particularly in the crisis area.
- The long term structural and other works likely to be required (from in the sea to the far edge of the swale)
- Recognition of how and where the unnecessary erosion of the dunes can be addressed, eg by raising invert levels , changing drainage and creating stormwater retention ( eg within the swale and Milford creek?)
How wind and wave action work together and will work together in the crisis locality. Artist impression is not good enough .(Need proper profiles and surveyed points)
SUMMARY
Incomplete discussion of the above issues to date means that the current Easter proposal needs to be more closely examined by outside experts with a view to establishing the means for retaining the dune system for as long as possible.
There is no discussion in the report of how previous management authorities have increased the erosion by carelessly placing tracks, fences, bridges and inverts in the dune system. The types of vegetation, fencing, access, walking and parking for the future must be part of a proper plan for this area.
Such a review would establish why Colac Otway Shire Council has taken my advice to stop development behind the dune at Marengo, but not taken my advice to acquire land (under the provisions of the Subdivision Act) and buildings near Milford Creek and change the drainage and land use there.
Proper planning of some of the north and south beaches must always include the possibility of almost complete dune removal, from time to time, at least . A review of the ongoing risks to the dune systems should also make recommendations about the location of the Great Ocean Road and other assets likely to be impacted.
