Professor Ian Turner and Associate Professor Ron Cox
Professor Ian Turner, Dr Kristen Splinter, Associate Professor Ron Cox
In a country with more than 10,000 sandy beaches, and where more than 80 per cent of the population lives within 100 km of the ocean, coastal erosion poses a considerable threat to Australian property and infrastructure.
“It’s a first order challenge to our society and the natural environment in Australia, as it is internationally,” says Professor Ian Turner from the School of Civil and Environmental Engineering’s Water Research Laboratory (WRL).
Climate change is escalating the threat to new levels, but contrary to some popular views, it’s not necessarily sea level rise that’s the biggest concern over the short-term.
“For the coming decades, relatively subtle changes in the number of storms that may occur per year, as well as changes in the size and direction of waves, could have a much larger impact on causing coastal erosion than sea level rise during the same period,” says Turner.
Currently it’s unknown how beaches will respond to more variable wave climates and storm frequency. “Will they adapt and be fine?” asks Turner. “Or is there some tipping point where we start to see dramatic coastal erosion?” If the latter materialises, he says the economic value of existing built assets in coastal communities that are at risk is probably immeasurable.
A report published in 2011 by the former Department of Climate Change and Energy Efficiency estimated that more than $226 billion of industrial, commercial and residential property, as well as roads, railways and other infrastructure, would face risks of inundation and erosion hazards if sea levels rose 1.1 metres. It’s a level that climate scientists have plotted as a high-end scenario by 2100, but haven’t ruled out.
And no less significant than the costs to the built environment, says Turner, are the much harder to quantify cultural and economic value of beaches, estuaries, marine parks and coastal ecosystems, which are all impacted by erosion.
Turner is a member of a team of coastal engineers at Water Research Laboratory interested in the role climate change is playing in the reshaping of Australian beaches and coastlines around the world.
Along with UNSW colleague Dr Kristen Splinter and their European colleague Associate Professor Mark Davidson from Plymouth University, he has developed a more reliable modelling tool – called ShoreFor – that can predict the rapid rate at which sand is carried off beaches during storms. Importantly, this tool can also predict the rate at which sand is restored, more slowly, by smaller waves between storms – a lesser known process known as “beach recovery”.
Making the models work requires estimates of future wave climates – which account for clusters of storms and larger, more directionally-diverse waves – and actual observations from beaches.
UNSW is part of an international network that uses cameras to monitor beaches around the world. WRL is collecting valuable data from a number of sites in NSW and Queensland including Narrabeen-Collaroy Beach in northern Sydney to extend a monitoring program at the site that has been running for 40 years.
Recently, a partnership with the UNSW School of Aviation has allowed aerial surveys of the beach immediately before and after storm events, augmenting data from quad bike surveys, as well as camera and rooftop laser scans. All of this information has been used to test the modelling tool.
If these models can be applied more confidently, says Turner, they can better inform the assessment and design of coastal defences, such as breakwaters and seawalls or beach nourishment and the enhancement of natural sand buffers.
Turner’s work on coastal erosion and beach recovery is closely related to other important projects in coastal engineering adaptation for climate change being undertaken by the School’s Associate Professors Ron Cox (convenor of the Australian Climate Change Adaptation Research Network for Settlements and Infrastructure ACCARNSI) and Bill Peirson (Director Water Research Laboratory).
With three years of funding provided by the NSW Office of Environment and Heritage under the Climate Adaptation Research Hub and support from the US Army Corps of Engineers, Cox leads research to optimise beach nourishment and adaptation of seawalls whilst Peirson is investigating the impacts of climate change on estuaries.
This multidisciplinary network of researchers is investigating ways to manage the risks posed by climate change, in order to help governments and communities develop suitable adaptation strategies.