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The degradation was so bad, with so much of the vegetation holding the dunes together removed, that the dunes were being blown literally into the urban streets. In 1970 rehabilitations works commenced, as reported in this April 1974 edition of the Soil Conservation Service of New South Wales, which lists what native species were planted, available to download in full online at: Soil Conservation Service of New South Wales. (1945). Journal of the Soil Conservation Service of New South Wales Retrieved from http://nla.gov.au/nla.obj-750393209

STABILIZATION OF AVALON SAND DUNES
BY D. D. H. GODFREY
Soil Conservationist

AVALON is one of the many popular resort beaches within the Sydney metropolitan area and is approximately 35km north of the city. It is located on a peninsular approximately 1.5 km wide bounded by the Pacific Ocean on the east and Pittwater on the west. The average annual rainfall is approximately 1 200 mm with greatest incidence from November to June. The permanent population of Avalon in 1966 was 5,247 and in 1972 it was estimated by the Warringah Shire Council to be 6,970.

The influx of holiday-makers, especially during summer holidays, results in these figures being doubled for approximately 3 months of each year. Day visitors to the beach during summer also impose a very heavy pressure on the beach and dune areas.

The Avalon sand dunes rise steeply from the beach to a height, in places, of 20 metres above sea level. The high rear dune gives an amphitheatre effect which protects the beach from off-shore winds and protects the residential area and business area from onshore winds (figure 2).

THE PROBLEM

Prior to stabilization work the high sand dunes behind Avalon Beach were unstable and drifting sand was encroaching onto the recreation area on the landward side of the beach. Sand blowing from the top of the high dunes was an almost constant source of irritation to the business and residential sections of Avalon and the problem was increasing each year. Sand blowing off the beach was contributing to a long-term recession of the beach line and general beach deterioration.

This situation commenced to develop in the early 1920’s. The dunal area was relatively stable prior to this as can be seen in figure 3. At that time the crest and the western slope of the dunes were stable because of the dense cover of native vegetation. The original vegetation on the area was dominantly tea-tree ( Leptospermum laevigatum) with some banksia ( Banksia integrifolia) and wattles ( Acacia spp ) chiefly on the fringes. Ground cover under the trees was sparse but undoubtedly in the more open areas sand spinifex grass (Spinifex hirsutus) and couch grass (Cynodon dactylori) were present in quantity. Some evidence of this association still exists on a small section of the dunes to the north where students and teachers forgather to study natural sciences.

Continued sand-drift and sand removal if unchecked would result in lowering of the dune height which would allow incursion of salt laden winds and break down the normally stable beach-bay-dune complex.

Figure 1.-Survey plan of the unstable dune area at Avalon Beach showing contour configuration prior to stabilization, approximate contours after stabilization and position of fencing, access and plantings. G 45725—2 

Figure 2. — The seaward face of the dune after fencing and some planting.

THE CAUSE

The removal of the protecting vegetation by the various activities of man including grazing and fire resulted in the problem beginning.

The basic cause of the extension and continuance of the instability of the Avalon dunal system and beach was heavy pressure on the area brought about by unrestricted use by the steadily increasing population.

The beach has a delightful setting and is considered comparatively safe for swimmers. The sandhills provide excellent recreation for young people and the steep landward slopes facilitate removal of sand for building and other purposes. The general increase in population, both permanent and itinerant and day visitors increased all of these uses. ’

CONTROL PROGRAMME

The significance of the problem was recognized in 1969 by the Avalon Preservation Trust who expressed concern to the Warringah Shire Council authorities. The assistance of the Soil Conservation Service was sought. The Service prepared a plan and recommended to the council a method of stabilizating the dunal area. The council adopted the recommendations, provided finance and carried out the work.

Work began on the stabilization programme in 1970. An important aspect of the remedial work is to recognize the cause of the problem and to remove as much of the cause as possible. The first important step was therefore to bring the problem and the proposed remedial actions to protect the local environment to the notice of the general public. Articles appeared in the local press, meetings were held, talks were given at local schools and publications describing methods of sand dune stabilization, prepared by the Soil Conservation Service, were distributed.

This local education programme aimed at informing the public of the need for the work and consequently at reducing vandalism which is frequently a considerable problem in such work.

The stabilization programme included the following steps:

Reshaping

In some places the slopes of the dunes were too steep to plant grass and the dune skyline was uneven having been formed into hills and hollows by foot traffic and wind.

The depressions in the uneven skyline acted as wind funnels considerably increasing local wind velocity through the low spots.

A bulldozer was used to reduce the slopes and level the crest of the dune so that an even skyline was presented to the wind. To accomplish this the overall height of the dunes was reduced somewhat. Height reduction was necessary in this case to prevent wind funnelling and to render slopes low enough for planting.

Dune Forming

There were two main areas where wind-blown sand was escaping from the bay-beach complex. At the northern end the prevailing southeasterly winds were blowing sand over the dune at a low point onto privately owned land and into the high school grounds. In the centre of the area a saddle on the dune crest coupled with a valley on the seaward side, increased the local wind velocity and sand was being blown onto the recreation area landward and even into Avalon shopping centre.

Figure 3. —An early photograph, about 1922, of the hind dune area of Avalon Beach shows the stable nature of the hind dune. Some instability had begun on the fore dune at the left-hand side of the photograph.

Figure 4.-Dune-forming fences were constructed in several places. This fence has built up the dune at the northern end of the beach prior to planting. At these sites it was necessary to increase the height and width of the existing dune.

Dune forming fences of plastic mesh were erected across these areas (figure 4). Vandals severely damaged fences but regular maintenance enabled the fences eventually to reform the dune to the required configuration.

Fencing

When the reshaping was complete a start was made on fencing the whole area to exclude the public from the area to be planted. The fencing was constructed with steel posts and wooden strainers and hinged joint fencing with supporting 10-gauge wires.

The whole dunal area was fenced from the Avalon Surf Lifesaving Clubhouse in the south to the small car park and land, privately owned until recently, in the north. On the seaward side the fence ran from approximately 30 m to 60 m landward of the mean high water line.

Beach Access

Incorporated in the fencing programme were fenced laneways which provided access to the beach. These were located over the dune in two places, at the clubhouse and direct from the northern car park area.

Figure 5.—A board and chain walkway provides access to the beach over the steep section of the access way.

The steep sections of the laneways were board and chain walkways as described by Barr and Watt (1969) (figure 5).

The remainder of the laneways were sealed with gravel.

In conjunction with fencing and provision of access to the beach, notice boards, requesting public co-operation, were erected at strategic points.

Primary Planting

During May and June, 1970, the planting of marram grass (Ammophila arenaria) commenced. The grass plants were collected from the Soil Conservation Service experimental area at The Entrance North.

Culms of marram grass were planted on an approximate 50 cm grid pattern and fertilized by hand with approximately 380 kg/ha of an N:P:K: fertilizer, 10:9:8. The newly planted grass was protected with a layer of brush (figure 6).

The brush matting prevented sand around the new plants from blowing out and trapped sand blowing across the area from the beach.

Very dry conditions in June, 1970, prevented the completion of the planting planned for that year.

A large proportion of this first area planted (adjacent to the Avalon Surf Lifesaving Clubhouse) was within reach of a watering point and was watered when possible. Consequently, results from this initial planting were excellent in spite of the very dry winter conditions prevailing in 1970.

Marram grass is a winter growing perennial and further planting could not be undertaken until April, 1971.

The winter of 1971 was again very dry. By early July, 1971, approximately 80 percent of the total area had been planted with marram grass when unfavourable weather conditions again stopped planting. Because of the dry conditions approximately 5 per cent of the 1971 plantings failed.

The marram grass planted in 1970 was topdressed with 10:9:8 fertilizer in April, 1971, and made further excellent growth.

During winter of 1972 all previous plantings of marram grass were topdressed with fertilizer and the remaining areas were planted. Most of the grass culms for this final planting were collected from the 1970 plantings.

In the process of fertilizing the marram grass, existing plants of the native sand spinifex were also fertilized. Sand spinifex responds vigorously to fertilizer and it is a valuable sand stabilizing plant. Its spread through the marram grass has been very satisfactory.

Figure 6. —Marram grass planted in August, 1970, was protected by brush matting.

Secondary Planting

Permanent stability depends on the establishment of plants with a long life span. Marram grass establishes and grows well in loose sand but its life span as a dense sward is limited and can vary from 3 to 15 years depending upon the site.

Once the sand surface is stable and some wind protection at ground level has been provided shrubs and trees suited to the local environment can be established.

In spring, 1972 and autumn, 1973 a range of suitable trees and shrubs were planted on the landward side of the dune. The planting included the following species :

Coastal wattle ( Acacia sophorae )

Cyprus wattle ( Acacia cyanophylla )

Banksia or coastal honeysuckle (Banksia integrifolia )

Coastal tea-tree ( Leptospermum laevigatum)

Coast rosemary ( Westringici fruticosa).

In addition sand spinifex is spreading naturally. Seedheads of this grass were planted in the summer of 1972-1973 on the lower seaward slopes of the dunes to ensure its spread into this important area.

Maintenance

Once stability is achieved it is essential that it be maintained. Vegetation has been introduced into a very infertile medium (sand) under very harsh conditions (severe winds, salt spray and possible vandalism). It can be expected therefore, that at least in the initial years vegetation will need assistance to survive and grow and that other improvements such as fencing may need repair periodically.

Regular fertilizer application, each spring and autumn, is necessary during the first few years after planting and thereafter periodic applications are necessary depending on the condition of the vegetation. This normally involves an application each three or four years of a fertilizer similar to N:P:K—--10:9:8 at the rate of approximately 200 kg per ha.

Occasional damage from storms, vandalism or fire may cause blowouts over small areas. An area damaged in this way will need to be replanted quickly, fertilized and protected with brush mulch to prevent the area extending.

Beach access tracks need to be examined periodically to ensure that they have not become unduly depressed over the crest of the dune. Should this occur the track can become a source for a blowout. In this event the track can be either replanted and relocated or replenished with sand and the board and chain walkway raised.

Beautification

When the area is fully stable specific planting projects can be undertaken on protected parts of the dune. The landward slope of the dune and the protected recreation and parking area can be planted to exotic shade trees or native plants unable to tolerate windblown sand or inundation by sand.

The stabilized dune allows development, to suit the area and the needs of the community, to proceed without the hazard of windblown sand, sand inundation and excessive salt-laden wind.

CONCLUSION

It has been demonstrated at Avalon that the ravages caused by man on our beaches can be healed and corrected but that to successfully do so requires control of public use of the area.

It is also apparent that the correction of this type of erosion depends upon co-operation between local residents, beach users, the controlling local government authority and the Soil Conservation Service. Without this willingness to co-operate the benefits are likely to be short term.

ACKNOWLEDGMENTS

The initial planning of this project was carried out by Mr D. A. Barr, formerly Research Officer with the Soil Conservation Service of New South Wales.

The Avalon Preservation Trust undertook public relations activities and actively supported Warringah Shire Council in the programme.

The helpful approach of the staff of Warringah Shire Council Parks and Reserves section facilitated the work. 

Reference

Barr, D. A. and Watt, B. G. (1969) —Pedestrian access to beaches. J. Soil. Cons. N.S.W. 25 (286-294). The Journal of the SOIL CONSERVATION SERVICE of New South Wales. APRIL, 1974, Volume 30, Number 2.

THE JOURNAL OF THE SOIL CONSERVATION SERVICE OF NEW SOUTH WALES Volume 30 Number 2 April , 1974

Issued under the authority of The Hon. G. F. Freudenstein, M.L.A. Minister for Conservation New South Wales. Published quarterly by the Soil Conservation Service, Box R2Ol Royal Exchange Post Office, Sydney, N.S.W. 2000. Edited by J. C. NEWMAN, B.Sc.Agr., Special Soil Conservationist. D. West, Government Printer, New South Wales—1974 G 45725—1

COVER: Part of a sand-drift area at Mona Vale which is being stabilized with marram grass by Warringah Shire Council. The Soil Conservation Service prepared plans and specifications to assist Council in the overall project.

Avalon sandhills pre re-vegetation, 1970. Photo: Gary Clist

Avalon Sand Dunes - marram grass planted out, 1970. Photo: Gary Clist

1970 - Horse on Avalon Beach, south end. Photo: Gary Clist

Avalon Beach, revegetated hind dune area, January 24th, 1986. Photo: Digital Image 400 - courtesy NSW DPI

In 1989 volunteer works commenced under the Friends of Avalon Dunes Dune-Care Group to remove Bitou - this now covered 80% of the dunes. In a 2013 interview with Marita Macrae, who had just received the Ruth Readford Award for Lifetime Achievement*, Marita shared an insight into the beginnings of this group.

The restoration and maintenance of the Avalon sand dunes has been a long term and quite big project – how did that start?

It had various beginnings. I was always interested in gardening and when I had the opportunity to do Horticulture in the late 1980s, part of this was a Bush Regeneration course. While doing this I learnt about Bitou bush. Also, Warringah Council as it was at this time, around 1989, started on the dunes as they were about 80% Bitou. 

The dunes are divided into paddocks, and you can see tracks between these. Warringah Council started in the one nearest to the surf club. They had a grant and got a tractor in there and pulled out lots and lots of Bitou. They then planted some natives – Coastal teatree, some Beach Spinifex and Coastal Banksias and that was it. The idea of those plants was to stabilise the sand after they’d pulled out the Bitou. 

Unfortunately Bitou is a terrible seeder, producing thousands and thousands of seedlings. In 1989 I used to watch what was happening. I had a young Labrador, Toby, which I used to take for walks behind dunes and watch the Bitou bush seedlings there.  The area to the north was still mostly Bitou. You can’t just start a job like that and walk away from it or the project would be a waste of money.

At the beginning of 1990 there two people, myself and a man who left Avalon a couple of years later, approached the Council and suggested we form a volunteer group to maintain what had been started and to continue it. That’s how it really began. 

What was the name of this volunteer group?

We called it Friends of Avalon Dunes Dune-Care Group, which was a bit of a mouthful. But in those days, the early 1990’s, it was part of a lot of work to control Bitou right along the NSW coastline, mainly on dunes, and also in the forests behind dunes. There were lots and lots of groups working at this – mainly north up the coast but also as far down as Tathra on the south coast There were lots of very good volunteer groups working along the coast and we just became one of those.

Ruth Readford I met when we got started in the early 1990s soon after we’d got started. I hadn’t known her before but she lived at this time at Ballina. She was a very good leader and organiser. She initiated telephone link ups and Dune Care conferences. We would meet in small groups and talk about our projects. She has written a book about community dune care at Ballina.

The restoration works which began in 1990 have an ongoing maintenance though – you have just reformed the group?

We were working on the Avalon dunes for about 20 years and during that time we’d had quite a few different grants. The Catchment Management Authority grant in the early 1990’s, a State Government grant, NSW Environment Trust grant and several Coastcare grants. I cannot take credit for receiving those grants.  I helped write them but I had a great deal of help from Pittwater Council staff, particularly Paul Hardie.  He always worked as a volunteer as well, right from the very start, despite having a young family. Eventually the Council, after our grants projects were completed,  took on maintenance and engaged bushcare contractors to work on the dunes. 

We thought everything was going well – the fact is that Bitou is a very obvious weed and people like to do big obvious weeds; they’re satisfying to do because you can see what you’ve done when the work is done. 

There are a lot of other weeds there though that benefited from the disappearance of the Bitou, Morning Glory in particular.

About a year ago I noticed that the dunes were still looking pretty weedy so I suggested about September 2012 we reform the group. We’ve been working one morning a month ever since.

Avalon Dunes - weeding with a view in 2013 - Weeding Spinifex grass - not much else grows in this windy salty place.

When and where does this group meet?

On the first Sunday of each month at 8.30am. We’re only working on a small section at this stage and have been meeting at the back of the dunes near the little bridge over Careel creek. Out major weed that we’ve been tackling is Morning Glory, which we’ve been doing for years. It’s a very time consuming insidious weed.

Although the Council still has contractors working here I think this one is best tackled by volunteers who don’t mind doing the fiddly work that you need to do to try and control it. This is not so easy for contractors that need to be able to show where they’ve been working to their employers. If they have a team of six people working a whole day on Morning Glory, you will not be able to see much difference. I think this is a weed better tackled by us volunteers. Many are happy to do this, others would rather find Asparagus Fern, Turkey Rhubarb or Bitou and tackle that.

*The Ruth Readford Award for Lifetime Achievement honours an individual who has dedicated significant energies, time and commitment to improving planning and/or management of the NSW coast. The Selection Criteria is described as: Positive impact of actions of individual either through employment or volunteer effort; length of time involved in coastal issues; and recognition by the broader community of individual’s contribution to coastal management.