Grant Leslie, Director Balmoral Group Australia
Over the past couple of weeks the issue of coastal erosion has hit the front pages of newspapers, TV screens and social media feeds with an east coast low hitting Wamberal Beach. The images of the same situation from Collaroy Beach in 2016 come flooding back. Some estimates suggest that around 400,000  cubic meters of sand were eroded from the Collaroy event. Over the past 100 years major storms have occurred along the NSW coastline in the 1920’s, in 1944, 1967, again in 1967, 1975, 1978, 1986, 2007, 2016 and now in 2020 according to the study published by Coastal Watch in 2016.
Most climate scientists, the community and political attitudes toward climate change are beginning to agree that there will be more frequent, more intense storms, bushfire events, flooding and drought. This is fast becoming the new normal and it’s playing out in front of us in real time, as the Wamberal event clearly demonstrates.
The sandy shores of our country are increasingly being exposed to these events. Australia has approximately 34,000 km of coastline (excluding all small offshore islands which if included would extent this to just over 59,000 km). 50% of our coastline is composed of sand - so about 17,000km of sandy coastline will be subject to storm activity and change over time.
The ABS estimate that 90% of the Australian population live within 100km of the coast making it one of the most urbanized coastal dwelling populations in the world. But more surprisingly Geoscience Australia have estimated that approximately 50% of the population live within seven kilometres of the coast.
More globally, a report by Arjen Luijendijk entitled The State of the Worlds Beaches estimated that 31% of the world’s ice-free shoreline are sandy. The analysis of satellite derived shoreline data indicates that 24% of the world’s sandy beaches are eroding at rates exceeding 0.5 m/year, while 28% are accreting (adding sand) and 48% are stable.
So, it’s clear from all of the research that this is a global issue and its not going away so we can’t ignore it. The Australian population is going to be more affected than in other places in the world. That's because we love the beach, right?
Much of the focus in recent years has been to understand the problem and try to estimate what the future looks like - to put it simply no one knows. What we do know is that as time goes by more and more of the population is going to be impacted one way or another by coastal erosion and there is no easy fix on this.
Engineering solutions such as beach nourishment, groynes, sea walls and the like are all options, as is a planned retreat option and all of these solutions come at a cost and have benefits. The cost and benefits derived from these solutions accrue to various parties, the affected residents, the surrounding community, the local government that has to manage the solution, and more widely the people that contribute funding to the solution (i.e. State and Commonwealth Governments)
The issue of who pays and who benefits is an emotionally charged discussion and there is no simple answer to this question either. Answering this question is something that our team have been working on for almost a year now. We have been looking at how we can dependably estimate the distribution of these costs and benefits and where they accrue to, exploring whether the various parties can afford to pay and more widely the intergenerational effects. To that end we have developed a new model called COAST™ that considers a wide range of hard engineering and socio-economic inputs to try and answer this distributional question.
Economic analysis of coastal erosion issues is critical in the overall solution so that its equitable across a range of stakeholders. We have found with recent projects that engaging us early in a coastal management project can greatly enhance the understanding of the development of any preferred solution and therefore the overall outcome.
If you want to find out more about COAST™ check out our website or get in touch with the team at BGA to find out how we can help with coastal issues affecting your community.
 Story by Coastalwatch Coastal Scientist Prof. Andrew Short and Dr. Mitchell Harley, Water Research Laboratory, University of New South Wales
 Coastwatch December 2016
 Geoscience Australia
 Article by Professor Andrew Short, Senior Coastal Scientist, Coastalwatch/CoastalCOMS