Wooli Beach Coastwatcher June 2012 – Subject: New Brighton Beach Scraping Trial

It is the intention of the author to post from time to time information, and comment related to the Dunal System.   The opinions are those of the author, or his contributors, and do not reflect necessarily the “official” line of CCPA who graciously allow this column. With the imminent release of the “new” plan and our weekend   meeting I feel it is timely to send my thoughts along to committee members at this juncture.

In January, 2012, the “New Brighton Beach Scraping Trial: Analysis of Dune and Beach Profile Data” was published by Rayner, Carley, and Coghlan of the Water Research Laboratory, School of Civil and Environmental Engineering, University of New South Wales. Contact person, Catherine Knight, Byron Shire Council (BSC), 70 Station Street, Mullumbimby, NSW, 2482. Hard copy of this report is already in the hands of several CCPA committee members.

This is an important document which was commissioned by the Byron Shire Council (BSC). Readers may or may not be aware I own a beachside property at New Brighton, in the Byron Shire, so these experiences and impressions are indeed first hand. In both areas there is neglect and misunderstanding of the dunal system at both an individual level and at a council level which has contributed to the bad state of the dune in both areas, particularly Wooli.   Recent beach scraping at New Brighton is helping to re habilitate the dune. I review key points of this document, and add comment applicable to the Wooli situation.

The background to this report:  resulting from severe storms in 2009 and 2010,  there was significant loss of dune top (my personal estimate, some 4 metres) along the New Brighton Beach.   My measurements at Wooli indicate a loss of about 7 metres also along the dune top at South Terrace.  The BSC undertook beach scraping along a 1.7 km section of beach September-October, 2010. See photos (to follow).   This activity appeared to be well conducted by the contractor, using at least three machines working in concert, and was accomplished over a week or so, with minimal dislocation to the recreational value of the beach.   There is anecdotal information that some areas were deliberately skipped as the immediate beachfront property owners were identified as having a “Green” ideology, and complained to Byron Shire Council (BSC) that “their” dune was not to be touched (!) — anecdotal I am sure. Skip areas would detract from the whole exercise. The timing of the beach scraping at New Brighton would appear to have been correct when the beach was naturally built up; at Wool,  locals will tell you that build up of the beach occurs towards Christmas..

Subsequent to this activitiy, there has been, in the eyes of  the  New Brighton  beachgoer and property owner, substantial build up of the sand dune.   It is noted, however, that no further measures have been undertaken at a Council level, but individual beachfront property owners have responded with plantings of natives including Spinifex grass,  Pigface, and  Native Morning Glory  to assist in stabilization of the dune face, and encourage further aggregation of sand with natural trapping of wind blown sand (photo to follow). Where these supplementary activities have been undertaken, it would appear that a greater degree of sand retention has occured; it is acknowledged that the additional benefits of planting have not been studied in this document.

Beach scraping is a traditional practice along the New South Wales and Queensland coastline, with the aim of restoring sand to the dune, and increasing dune mass.   It was widely undertaken following the cyclones in 1974. In fact, the New Brighton dune was actually built at that time…it is a man- made structure.

At first glance, reading the introduction,  the document is a bit  short on back ground history.    Is the descriptor “Trial” correctly used?  First paragraph, p 6 “feasibility” should perhaps read “impact”, and comment “unlikely to be sufficent to fully offset present and future coastal hazards”  this  is not the point of the study i.e. a conclusion that does not follow from the study data. The report says that “the scale of beach scraping is unlikely to sufficent to offset coastal hazards and/or future climate change”. We all accept that beach scraping in itself is not the solution, but should be viewed as part of a system of dune management. However, once these matters, which have an ideological flavour, are set aside, then the document’s research findings can be considered.

The method looks to me reasonable, but I query the need for the number of survey sample sites.   The report does not note that between about location 41 and 42 there is a buried rock groyne which would inhibit north ward flow of sand. This groyne would appear to be successful in limiting northward flow of sand.   Readers may be un aware the New South Wales   legislation prohibits the building of “hard structures” in areas of coastal erosion, which is a pity as they have a part to play in the protection of coastal communities. The impact of beach access points is not really considered as these were not really  stabilized in the exercise, and there is sand erosion occurring where people walk through.

Page 9, information was collected by “Council’s surveyors”.   The Byron Shire Council (BSC) is not known to be impartial in it’s beliefs, and actions.   Were the surveyors independently contracted?

There is an important point at the bottom of page 9 where it talks about small changes in the lower beach induce relatively large changes in the contour of the dune; consistent with the general understanding about the importance of dune toe reinforcement. Simply put, if the  base of the dune erodes, the sand above will collapse down, to reform a natural angle of about 30 degrees (this can be seen in the well grassed healthy  dunes south of the houses on South Terrace at Wooli).

Following beach scraping, the total effect was average seaward gain of some 5 m.   Comment, although the dune top has not been reformed to its previous position a seaward gain at the base of the dune not only creates a significant buffer zone to protect houses, but also restores the natural dune contour thus the dune is more stable over time.

If I read  the report  correctly, the scraped sand is replaced over time by natural “longshore onshore sediment transport”, an important point. At Wooli, it is often possible to discern dissolved sand in the surf which is available to be deposited back onto the beach to replace sand moved shoreward by beach scraping.   On page 28, there is a recommendation that future works should create a slightly higher and wider dune, which we all would agree with.

On page 17, it talks about wind effect, commenting that easterly winds help to bring in sand.   This I think underscores the point that there are differences in beach sand ecosystems, and, although the general principles remain, no two are exactly the same. Locals at Wooli will tell you that the easterly wind brings direct wave action which actually erodes the beach, but that the  winds  and wave action from the north east help to deposit sand on the beach.  This report makes no reference to trapping of wind blown sand which has not be undertaken at New Brighton. At Wooli, sand trapping (see previous column) is effective and is contributing to build up of a fore dune; with build up of sand on both the north and south sides of the sand fence.    Item 3.3 reviews the impact of Wave Climate and notes that there was an overall lack of extreme events during the survey period. Recall back to 2009 and 2010 when extreme weather took at least ten feet off the top of the dune at New Brighton, and see their pictures page 27. I was there. Without going into detail on this point, the report seems to be acknowledging that the “extreme” events were the main factor in the large degree of dune loss, without actually postulating sea level rise, from climate change/global warming (etc.).

Comment and conclusions. Consider first, some basic economics. Are these measures “cost effective”?   1.3 km of beach was scaped,  I believe at a contracting cost of $160,000.00 (information from the Byron newspaper “Echo”) which equate to  $123,076.00 per km. From a political point of view, that fact that this was untaken by the BSC, a known supporter of the “Retreat” ideology for Coast Zone Management was quite significant.   Even BSC is aware of the economic impact of protecting properties along the coast.   Applying this cost to the dune side properties only, assuming there are 25 properties per km(average home frontage 40m),  it is $4,850.00 per property; less if this amount is amortized over the general community.   Land tax alone on these properties is $12,500 per year.  If this event was undertaken once every five years, over this time some $62,500 in land tax would have been paid, so the government is well ahead on its investment. Beach scraping has resulted in the restoration  of a protective dune leading to greater confidence in the property market, which in turn creates rates and land tax for government.   I estimate there would be at least a  20 –  fold multiplier to the value of   coastal properties from this investment in dune rehabilitation, potentially adding 20 x $4,850.00 equals $97,000.00 on average to the value of  New Brighton beach front properties.    This is in contrast to Wooli, where in the last year their have been to my knowledge only three house sales, and at last count there were twelve properties with for sale signs up.   Beach front values at Wooli are about one half of  what they were pre 2009.  The most recent sale of a partially completed house, for $680,000 is not far off land value, hence there is little added value along the Wooli Beach strip for DAs, and capital improvements. At Wooli, there is public land, including the school along the dune strip.  As others have questioned, what would be the cost of relocating the school compared to basic measures to protect the dune?

CVC documents written, it would seem, to avoid to doing anything to protect Wooli, comment that “for environmental reasons beach scraping is no longer a viable option”   (refer their “Wooli Beach Rehabilitation Plan”, 2005, page 4).  This conclusion is quite spurious.  Yes, there are “things” that live in the sand (but lucky for us not to the same extent as  Frank  Herbert’s sci fi classic “Dune”)  which form part of the beach ecosystem and it is right to consider their role, and impact on them of beach scraping. But, at the end of the day, if there is no beach, there will be no where for them to live, anyway. The part II of this study, examines the effect of beach scraping on beach micro fauna, and will be reviewed in the next edition of the Wooli Coastwatcher.

In conclusion, the   “New Brighton Beach Scraping Trial: Analysis of Dune and Beach Profile Data” is an important and timely  study that demonstrates retention of dunal sand following beach scraping.   The conclusions of this report   support the  application of  beach scraping  in coastal areas threatened by dune erosion.   The report  does not comment on further measures to preserve the dune.   All are necessary as part of a coordinated response, to achieve the best results. The BSC is to be congratulated for its efforts, but also needs be reminded of the need for further measures, including sand trapping, and  stabilization of sand  mass with plantings.    Our ability to re build dunes eroded by storm and tidal surge will allow protection of property in Coastal Hotspots, especially Wooli,  for many future years.

Dr. Roger T. Welch

6/6/12.

The sand beach and sand dune are a dynamic system that ultimately affords protection to the Wooli township. While the width of the beach is important for this protection from the effects of wave and tidal surge, the main structure affording protection is the dune itself. If the dune were to go, then beach front homes would be claimed by the sea, and the town subject to inundation as the sea breaks through and joins with the river. The beach is a mobile system that comes and goes with actions of the sea, and wind. Since we have limited ability to influence these natural events that affect the width of the beach, our measures must focus on the protection, stabilization, and regeneration of the dune.

Do readers realize the Clarence Valley Council (CVC) in 2005 adopted their “Dune Rehabilitation Plan” which outlined best practice of the day and contained all the working material for the protection of the dunal system at Wooli? If the Council had followed their own plan we would not be in the situation we are in today, with loss of at least three metres of dune top since 2009; nor would the Council have needed to push the doctrine of “Retreat”, as if to cover the sins of their own omissions and neglect. Copies of this management plan are available from roger@eyesight.net.au. Private individuals have made significant investments in Wooli property based on this and other accepted codes of responsible action by Councils to protect property; however, in the hands of the Clarence Valley Council, at best, beach front property owners faced neglect. Matters worsened considerably in 2010 with the promulgation by the Council of the “Retreat Policy”. When coupled with the Frank Sartor legislation (“Coastal Protection and other Legislation Amendment “), property owners were faced with their properties being condemned, as has happened at Taree Old Bar, and as the Byron Shire Council is currently attempting to do at Belongil Beach. The Sartor legislation remains on the books, and has not been undone by the new State Government who despite their pre election assurances now with their “committee approach” seem to be vacillating on the subject of protection for coastal communities.

Some newsy items:

The floods of Christmas 2010 brought deposition of logs and other material (even a dead cow!) onto the Wooli Beach; this material was bulldozed up towards the base of the dune, without any movement of sand (another lost opportunity by CVC as this material could have been used as the foundation of a new fore dune, then covered with sand). Where this material remains (unfortunately much has been removed to for bonfires) there has been further aggregation of sand and support for dune vegetation. As well, bulk physical material may impede erosion of the base of the dune, the critical area, in the event of storm-tidal surge as happened in March, 2008 when at least 3 meters was lost from the top of the dune. It has been a blessing for Wooli beach that this material arrived when it did. As previously noted, far more money has been spent inland dealing with the aftermath of these and recent severe floods, than has ever been spent to assist repair of the dunes at Wooli. This point should be appreciated by those city and inland taxpayers who do not want to contribute to repairs at Wooli; the rates system is not by location, it is “all in” and Wooli rate payers all contributed to saving Grafton.

On Tuesday, January 11, 2012, a tracked front loader-excavator vehicle was on the beach for about 5 hours; some repair works were undertaken to two beach accesses, with pushing up and packing of sand. Beach scraping was undertaken and by all accounts, the driver did a neat job with minimal impact on the level of the beach. Apparently this was in response to letters of complaint to CVC. Photo shows   an area of repair, without sand bag reinforcement. Unfortunately, other areas of sand bag access were not fixed, although CVC has been asked to do this. With a rough guesstimate of costs, 5 hours plus travel time, half the cost was involved in just getting the equipment here, when a more thorough job is needed. We are however fortunate that some works have been undertaken, and there is now clear precedent for putting mechanized scrapers on the beach. The community can see the benefit of sand works with safer beach access, as well as the role of sand relocation to preserve and protect the main dune. The works areas shown do have bare sand, which needs to be planted and stabilized so it does not blow away.

I would like to share some further observations and thoughts:

Walking along the beach one can see different areas of dune topography and vegetation cover. South of the houses there is a lower dune that is generally well covered with Spinfex grass, and other natives, which in turn are travelling seaward along the beach, and thereby helping to aggregate blown sand, which in turn will create a stringy buffer to wave and tidal surge. Walking northward, in front of the houses, it is another story: there is much variation in dune “health”. Photographs taken January, 22, 2012.

Bitou bush. There are numerous areas of Bitou Bush Chrysanthemoides. monilifera ssp. rotundata. Bitou is a fast growing plant introduced from South Africa which overtakes our native dune plants. Native plants are considered to have greater sand retention properties, and for this reason there is a coast-wide campaign to control bitou bush. The Byron Shire Council has undertaken to spray dune areas from helicopters with the plant poison Glycosate, overriding the objections of its citizens who do not want to be contaminated with a toxic chemical. In 2010, I attended a public meeting in Byron to protest Heli-spraying. Volunteer Dune Care workers have now got stuck in and along several beach areas are pulling out the Bitou by hand. In areas where the bitou has been sprayed, dead zones result. Sand can easily be blown away from these dead zones. And, based on experience at New Brighton, NSW, the killing of Bitou with Glycosate herbicide, leads to death of other plants due to persisting action by herbicide residual in the sand/soil. Best management, as practiced by Wooli Dune Care, requires hand pulling of Bitou, and replacement with natives, done as a gradual replacement process.

Deposition of rubbish, garden clippings, palm fronds, and so on is advocated by some as a long established practice to stop the sand blowing away. We need to have a re think about this. The best way to stop sand from blowing away is to have vigorous growth of native plants. Residents are asked not to dump stuff on the dune face, and where this has occured, to undertake plantings, using the material as shelter while the plants get established.

Plantings. A key focus of Dune Care activities is the planting of native plants to help stabilize and grow the dunes. All residents are reminded that CVC has funded via DuneCare native plants which can be obtain from Minnie Waters Nursery, phone: (02) 6649 7993. I strongly suggest you take the opportunity to speak with Mr. Dennis Milne, for information and guidance on plantings. Mr. Milne is a truly dedicated man; it is worth the trip up there if only to make his acquaintance. This is a fantastic initiative and should be well supported by all residents. Get your free allocation, then tip in and buy some more to support a good cause. The key plants are: beach grasses, Kangaroo grass, Themeda triandra, and Spinifex sericeus for the flat areas at the base of the dune and onto the beach; Sesuvium portulaca-astium where the dune face starts to curve up; and Pigface, Carpobrotus glaucescens, into the face of the dune. See photo of plantings undertaken under the auspices of Dune Care, which show new plants nestled in pockets in the existing old cuttings for protection while they get established. As they grow up, the dead cuttings will be removed. Pandanus may have a role down on the beach, but I am not sure what the experts think about this. I have established a Pandanus nursery at New Brighton and would be pleased to provide baby plants in pots at no charge, just return the pot so I can grow more from seed. (Please contact me via: roger@eyesight.net.au ). Native wattle is recommended for dune top as an alternative to Bitou, and will grow to a height of up to one metre when exposed to prevailing winds, so dune top residents can be reassured that these plants they will not detract from their dune top views. Trees such as Shioke, planted into the dune face, are not as effective as ground clinging plants; indeed, when they are eroded, their shallow root system can pull away the dune as the weight of the tree topples it over; there is a concentration of these trees on the dune in front of the School where interestingly, there is remarkably little in the way of incipient dune build up. The dune face in front of the school appears to have more of a vertical configuration, and thus is probably at more risk of collapse than other areas.

Sand fences. Photos show sand aggregation from sand fences. Dune Care is now on its “third generation” fence with serial improvements to design and construction. Special acknowledgement to CVC for making funds available for materials, and great work by our hardy band of Dune Care volunteers. As the workers will confirm, a cold beer tastes even better when it is enjoyed immediately after building a new sand fence! A key design feature is the gauge of mesh, large enough to let the wind through, but small enough that precious grains of sand, are stopped in flight, and drop to the base of the fence. Sand fences built just over one year ago are nearly buried, so at least a metre of sand has built up; and recent work pre Christmas 2011 along the southern beach already shows sand accumulation. The fences appear to capture sand blown from both a northerly and southerly direction. Plantings of Spinifex grasses further compound the positive benefits of sand aggregation. Some people say that due to climate change waterfront properties are doomed; but sand accumulation does help to provide a “Sand Bank” that will lessen the effects of storm and tidal surge, which is the real problem we have seen at Wooli over many years. Then effects of putative sea level rise are not only hard to quantify, but probably at the present time of lesser significance to Wooli Beach. Other methods of sand banking are being explored, to create a buffer between the ocean and the base of the dune. Protect the base of the dune, you will protect the whole dune, thus also protect the properties, and the town.

Dune base gutter. In some areas a dune base gutter has formed. In the event of waves reaching the dune toe, these gutters would channel water along the base of the dune, scour out the base of the dune, and lead to dune fall in as the vertical dune re shapes to a graded contour of some 30 degrees.Some form of filler/buffer is needed here; perhaps sand bags placed along the dune base as a back stop measure, then covered with sand, and where there is bare sand, planting over the top. Again the role and value of plantings to stabilize sand as crucial to the whole process of dune refurbishment and stabilization. More work is needed in this critical area of dune toe reinforcement.

 Vehicular access to the beach. Given the potentially unstable nature of the dunal system, I personally believe that recreational four wheel drive vehicles should not go onto the Wooli Beach, at least opposite the houses. Disregarding the Hoon element, the vehicle tracks can cut into the beach. I enjoy driving my old truck on the beach up to Sandon, part of the great Aussie experience, but there are no houses on that stretch of beach. For the fishermen, there are multiple walking access points to the beach opposite the houses and south towards the seaway. Could we call for a voluntary moratorium on driving on Wooli Beach? Although we are over signed, perhaps a suitably worded sign at the access roads, asking for consideration and voluntary limitation. Similarly, driving of vehicles along the dune top in front of the houses is to be discouraged.

As we come to appreciate the benefits of current efforts, we realize there is more still to be done,especially the construction of sand fences moving north along the beach, and planting of natives to stabilize the dune. I would propose a simple report card to beach front property owners, with recommendations on clearing of bitou, removal of rubbish, and appropriate plantings and will explore this with our local Dune Care organization. Thanks to everyones’ efforts including local residents, and Dune Care, with the support of CVC, we are certainly kicking some goals. Please get behind your Wooli Dune Care. Call Len 02 6649 7486 or see Bruce Bird at the Wooli Post Office, and join up.

Author: Dr Roger Welch