Stuart Nettle September 22, 2009

The Australian coastline is being loved to death. Our passion for the ocean and our obsession with real estate has meant that we've built right up to the coastal interface. At certain places where such development has occurred properties are now being reclaimed by the ocean. Examples can be found at Collaroy in Sydney, Norah Head on the Central Coast, Coffs Harbour, Byron Bay and the Gold Coast. The public response to these properties falling into the ocean appears to be a particularly Australian strand of schadenfraude; a pleasure in watching the misfortune of others mixed in with our home grown tall poppy syndrome. The inference being that people losing their property deserve this fate as only wealthy people can live right on the coast and they chose to build there. Therefore they deserve to have their wealth get washed away and not be reimbursed. But this response oversimplifies the problem. Most coastal properties were approved and built in a time when coastal processes were less well known  than they are now. Also, the decision to build is granted by council, so how complicit are they? And should they pay the current owners compensation? Belongil Spit, just north of Byron Bay, recently suffered severe erosion following an above average  storm season in the Coral Sea. Belongil has received a lot of news coverage recently as it has passed through the court system. The owner of a block of land on Belongil Spit, John Vaughn, was dumping material on the beach outside his house to stop further erosion. Byron Shire Council sought an injunction as his actions were not in keeping with the councils 'planned retreat' policy. Vaughn responded with his own writ stating that the council-built groyne at the Main Beach carpark in Byron Bay contributed to the problem at Belongil. Recently I spoke to Dr Rob Brander from the School of Biological, Earth and Environmental Sciences at the University of New South Wales about the situation. Stuart Nettle: At Belongil the houses in question are built on the Belongil Spit, can you describe to me, in geological terms, what the characteristics of Belongil Spit are? Dr Rob Brander: Belongil Spit is only a small part of a large coastal embayment beach system that extends for 30 kilometres from The Pass through to Hastings Point in the north.  As is the case of most beaches on the east coast, it has been there for about 6500 years ago when it was established after the last major rise in sea level. Due to the prevailing south-easterly swell direction, the dominant drift of sand is from south to north. Belongil is called a 'spit' simply because this section of beach is intermittently open and closed by the Belongil Creek inlet and the spit itself separates the ocean from the Belongil Creek estuarine system behind. There is evidence to suggest that the beach is quite stable. If you look at an aerial photograph you can see a series of lines  parallel to the shoreline as you head inland from the beach just north of the Creek entrance.  These are old beach ridges indicating that the beach has actually been building out since it’s formation meaning there is a lot of sand around in the embayment. If it's building out, why then is it unsuitable for permanent dwellings? Spits in general are considered to be dynamic and mobile systems due to ocean storm events and river flooding which can cause a sudden shift of the position of the river mouth.  For this reason they are not ideal for permanent dwellings or structures. Unfortunately they are beautiful environments with nice views and the average coastal home buyer has little basic knowledge of coastal processes and landform behaviour. I’m not sure if this applies to the real estate agents as well! The Byron Shire Council has adopted a 'planned retreat' strategy, is this is an intelligent move on behalf of the council? There are four primary coastal management options in response to an eroding shoreline.  The first is to “do nothing” and let nature take its course. The second is “retreat and relocate” and the third and fourth involve soft (dune and beach nourishment) and hard (groynes and seawalls) coastal engineering approaches.  From what I understand, Byron Shire Council is doing a mix of options the first and second. A planned retreat strategy always makes sense in situations where structures have been built too close to the coastline, particularly in wholly inappropriate locations such as Belongil Spit. The basic idea is to accept that a mistake has been made and to somehow convert the beach/dune system back  to it’s natural state. While this sounds like a great plan, the problem is that homeowners are often unwilling to move, and who can blame them? So from an environmental perspective, it is an intelligent move, but it’s a logistically difficult solution and, as we’ve seen, often a controversial and unpopular one. What are the legal ramifications? I’m not sure what the legal aspects of planned retreats are. James Lancaster is the head of the business lobby group Byron United, he says a planned retreat is ludicrous. Among other things he says that, if left to nature, the ocean would flood the Byron CBD. Does his argument hold water? That pun is fully intended by the way... I would say that he clearly doesn’t understand how coastal processes work or what planned retreat means. To say that a planned retreat will lead to flooding of the Byron CBD is completely ridiculous. Flooding of that nature would require the absolute worst case sea level rise scenario to occur, which is not going to happen overnight with some monster storms superimposed on top. A planned retreat would allow for re-establishment of the natural dune system which would actually  provide better protection than the existing houses and ad hoc erosion protection works provide at the moment.. John Vaughn owns one of the houses that has lost land to the sea. He was recently taken to court for dumping rock material on the beach in front of his house to prevent further erosion. Vaughn claims that the cause of the erosion is the council-built groyne at the Main Beach car park to the south of his property. Is this a valid argument? I’ve  met John and been to his house and completely sympathise with his situation and it really is terrible. It’s shocking how much of his backyard he’s lost since I was there two years ago. Unfortunately I don’t think the outlook for his home is very good and his own remedial measures will only provide a brief respite. The groyne is a contentious issue. Groynes are built to trap sand moving in a preferred direction due to longshore drift. While they are great at building up sand on the updrift side, they can dramatically reduce the sand on the downdrift side.  As sand in the area generally moves south to north, John is arguing that he is directly affected by the reduced downdrift sand supply. He may very well be right as erosion at Belongil only really started in the 1960’s after the groyne at Main Beach was built. It’s also not just the groyne that sticks out into the ocean, but the entire complex consisting of the parking lot, pool area, and rock revetments.  According to a study by Dr Ian Goodwin, a coastal geomorphologist at Macquarie University, it is estimated that the combination of the groyne and artificial headland has caused Belongil Beach to erode back 30-35 meters from a reduced northwards sand supply. However, if you look at any aerial photo or even the Google Earth image, it’s clear that the stretch of houses including John Vaughn’s physically protrudes out into the ocean because they were built far too close in the first place. To me, this overrides any effect that the groyne may have had. So you don't agree that, because the natural flow of sand has already been interupted, further human intervention is justified? I don’t agree with it at all. That’s like saying “we’ve stuffed it up already so it doesn’t matter if we stuff it up a bit more” which is a very dangerous attitude. Once you start building groynes and seawalls it can often lead to a domino effect of similar knee-jerk solutions that don’t solve the original problem. You just end up with a lot of ugly groynes and seawalls and a mediocre beach. The  houses should never have been built on the seaward side of Belongil Spit in the first place. Can the spit be stabilised without affecting areas further north? Any section of coastline can be stablised with the use of seawalls and other types of revetments. However, while this will stabilise the position of the shoreline, it generally won’t do any favours to the beach. So you gain a house and lose the beach in front of you. The question is: who gains and loses from this? Yes, the handful of house owners will benefit from not losing their homes, but how many thousands of beach goers will lose out from a badly eroded beach? Seawalls and groynes are known to have impacts on adjacent sections of coast. However, in this case, I think the upstream effects of a seawall running the length of the Belongil Spit wouldn’t extend much beyond the mouth of the creek itself. Any other points you'd like to make Rob? The bottom line behind this issue is this: is it worth spending millions of dollars for the benefit of a select few or should we be looking at sustaining the beach as a public amenity for all to enjoy? It’s a very important question because if sea levels do start rising significantly and coastal storms become more frequent, there will be many more Belongil Spit scenarios up and down the east coast. It’s interesting that the main erosion problems are in places like the Gold Coast, Byron, Noosa and Coffs, which are all popular tourist destinations where the temptation to develop close to the coast has been great. There’s a nice saying that goes “there’s no coastal erosion problem until a structure is involved” and it’s very true. We should also never forget that coastal erosion is a natural process, sea level rise or not. Rob Brander has his own website www.scienceofthesurf.com