This is a Grey Conservation & Community Association project

with support and authorisation from DEC (CALM) and with Commonwealth funding (~$7,000 from the Enviro fund round 10).

• Why do we need to rehab the dune?
• What can we do?
• The theory behind the plan
• The Plan from the funding submission
• What’s next?

Why do we need to rehab the dune?

The dune will march right through the southern section of the settlement engulfing shacks in its path if it is not stopped. On top of this we will loose the southern back beach. The dune is rapidly harvesting sand from this beach, for those who haven’t been up to Grey over winter, the back beach has lost up to 1.5 metres of sand over and above its usual seasonal shifting. There are huge exposed rocks where once there was beautiful sandy beach.

What can we do?

We are lucky to have a scientist from Curtin University as a shack owner (Peter Sheppard) who has put together a well researched rehab program that was commenced over the October long weekend. Those efforts have already been rewarded with substantial slowing of the dune. Peter has devised an excellent plan that not only rehabs and stops the dune’s progress but allows for community access to the dune, in particular fun activities like sand boarding. We all know sand dunes are a wonderful source of entertainment for our younger (and some not so young) community members and as such a portion of the dune has been fenced for this purpose, there is even a plan for a dune top lookout, where I can hear many corks popping at sunset!

The theory behind the plan

There are many ways of stabilising a sand dune and the bottom line is to stop the sand from moving. If you can’t or don’t want to cover it in bitumen then the alternative is to slow down the wind close to the surface (a wind break). The material used to do this can be literally anything that will not blow away. It ranges from car bodies, brush, seaweed, stones to vegetation. If you care about the final appearance then something natural like vegetation is desirable but you have to protect it until it is established and can be its own wind break. If this fails then the sand moves, buries and kills the vegetation and the dune starts moving again. Human and stock (animal) activities on damaged and recovering dunes have a significant influence especially during summer.

A simplified sand dune is shown in figure 1.

The dune moves or migrates with the prevailing wind by picking up sand from the tail (A) and depositing it on the leading edge (B). If you cover the dune with a layer of material (green) then the wind is forced away from the surface and little or no sand migrates to B as in figure 2.

If the layer is thick enough then the wind at the surface is not strong enough to pickup and move sand as in figure 3.

Ideally you want to cover the whole dune and stop it in its tracks. This requires significant effort and is only possible for small dunes like the one at the southern end of Grey. Larger dunes require a different strategy. The key is to cover the tail (A) as in figure 4. Part of the dune will still migrate but in doing so will take sand from the top of the dune and it will eventually slow down and flatten out as in figure 5.

In Vietnam 80km long dunes created during the war have been eventually stopped by growing vegetation on the dunes tail (A). There are now orchards on some dunes.

The Plan from the funding submission

(a)    The purpose of the project is to stabilise and re-vegetate a denuded sand dune and prevent adjacent coastal dunes from further erosion.  We will cover the dune with collected brush and possibly seaweed to shield existing and new vegetation from the wind and sand abrasion. It will also reduce grazing on the smaller seedlings by kangaroos. The dune will be replanted directly with local species that have germinated during the winter. Sewing collected seed will supplement this as will planting out some 1,200 established seedlings that will be raised at Grey in plastic pots.  We will erect 0.5km of fencing to isolate the denuded dune from human and animal access and to direct beach access around the area. To create a beach access that is erosion resistant we will create a dedicated and marked path that will have a wind protected North-facing entry at the beach end. This will require some minor excavation.  A second 0.05km reinforced fence/wind break will be erected to the West of the beach access path to create a wind break and maintain the paths integrity. Strategically placed signs and pairs of posts will be located to the south of the dune to prevent off road vehicle and motorbike access into the area and protect partly eroded dunes to the south of the main dune. Existing tracks to the east of the area will be closed, covered in brush, barricaded and sign posted. Education using the associations web site, strategically placed information boards and the DEC ‘let it grow’ signs are also expected to take human pressure of the fragile dune zone.

(b)    Most successful dune stabilisation projects are based on isolation and re-vegetation. In this case we have the distinct advantage that in 2006 Tristan Nunn did a case study with DEC support and encouragement on this particular dune at Grey because it was recognised that it needed to be stabilised and revegitated.

(c)     This particular dune is steadily migrating northward, currently at about 5m per year. Unfortunately there is amply photographic evidence to show this. Even the latest aerial shots by DEC and available Google images are quickly outdated. Success will be measured by the level of future migration and the long-term viability of the replanted vegetation on the denuded dune and the natural ‘infill’ of vegetation on the partly eroded dunes to the south.

(d)    The Grey Conservation & Community Association (current members from registered shacks) has a track record of rationalizing tracks by covering areas with brush to exclude traffic and allow regeneration of the native flora. The Grey Conservation & Community Association has assigned two elected committee members to this project and we will maintain the fencing and signs as required. Another measure of success will be educational; via the web site and the erected information boards. This will be best measured by the community turnout on activity days and support for this and future conservation projects.

It is anticipated that this project will reinforce the already strong community spirit at Grey and result in an even lighter impact on the fragile coastal dunes around the settlement.

What’s next?

To consolidate and finish the plan your help would be fantastic. There are small ongoing jobs that will be the icing on the cake and complete the plan. Even if you can spare just an hour when the fish aren’t biting, would be greatly appreciated. The activities that need attending to are:

1. We need to eventually cover the whole dune with brush then plants so at anytime collecting and laying brush is a great help. When you clean up the fire hazards around your shack bring the brush and vegetation debris to the dune.
2. Build wind breaks. Almost anywhere along the North-south gully in the centre of the dune create walls of posts, rails, old pine pallets and preloved carpet. See diagram or create your own design.

3. For the younger people one really great help would be to cart materials onto the dune from where its dropped. (About half way along the Eastern side).

Peter Sheppard (Project Leader phone 0401103143) will be at Grey on the following dates 8-9 Dec 21-23 Dec 27 Dec-2 Jan
In shack 22 about 50m west of the dune (one with two wind generators) so just call in and see what is current.

Achievements to date:

• 8000L water stored on dune to support trickle irrigation.
• Planted out 150 plants and set up trickle (with a timer) for them.
• Set up all required wind breaks and fences.
• Created a sand boarding zone in the NE corner.
• Brushed about 50% of the dune(Target was 75%).
• Deliberately keeping the west face un-brushed for now in the hope that sea breezes will continue to push sand away from an endangered shack.