Just a few hundred metres from Moruya airport, Bengello Beach looks like any other typical Australian shoreline.
But among coastal geographers, it’s globally renowned for providing the longest continual data set of beach change in the Southern Hemisphere.
And what this half-century of data reveals is the staggering resilience of nature — and what the future may hold for Australian coastlines.
The study began in 1971 when Australian National University professors Roger Maclean and Bruce Thom travelled from Canberra to the six-kilometre stretch of beach on the New South Wales south coast, to start recording sand movement at four locations.
Every few weeks they would set up tripods and use a measuring rod to calculate changes in sand volume and beach profile at the four key points, often wading into the water — sometimes treading water — for accuracy.
They would snap some photos and jot down measurements and field sketches in their notebooks.
Bengello Beach was chosen for its east-facing profile, and for ease of access for the two coastal geographers who wanted to spend more time there, Professor Thom said.
They measured Bengello throughout the intense La Nina storm period of 1974 to 1976, when the equivalent of 12 concrete trucks’ worth of sand was removed from every metre strip of the beach.
Over the next six years, they noted that the beach regained the sand it had lost during the 70s.
Professor Thom said storms had made the biggest impact on the beach.
Yet, in a paper released this year, after 50 years of the study, he said the main lesson from tracking Bengello was its natural resilience.
“There’s been really no change over all that time in terms of the amount of sand and the position of the beach,” he said.
“With storms, the sand goes offshore but the sand comes back again.
“Bengello showed us how sand can recover. Nature is the best healer.
He it was important not to interfere with nature unnecessarily.
“We have remarkably resilient beaches,” he said.
“But we can interfere with that resilience if we put structures in place that cause loss of that sand.”
Passing on the baton
University of New South Wales coastal science expert Thomas Oliver took on the project from the professors six years ago, in what Professor Thom said was an attempt to “pass the baton on to the next generation”.
However, he said he still occasionally ventured back into the sand dunes.
Using satellite technology, which was introduced in the 1980s, coastal geographers can recreate beach profiles dating back 40 years.
“The significance of this study is that it captures that little bit of change that occurred before [satellites], and especially captured the storms of 1974 — which are the most significant in the last 50 years,” Dr Oliver said.
He now carries on the 50-year tradition and travels to Bengello monthly to take a new data set.
“I’ve been handed this amazing legacy of data,” Dr Oliver said.
Some things, however, are different.
Dr Oliver uses a real-time kinematic GPS with sub-centimetre precision to electronically log the sand’s volume.
New wave buoys were installed in 2020, monitoring wave action near the shoreline.
For Dr Oliver, the significance of the study remains the same as for the professors.
“The more we understand [how the beach responds to different weather events] the better we can predict what might happen in the future,” he said.
“We don’t yet see a very clear signal of sea level rise but my sense is that it’s going to appear in the next 50 years.”
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https://www.abc.net.au/news/2023-11-05/bengello-beach-longest-sand-monitoring-study/103057228 At Bengello Beach, longest-running coastal study in Southern Hemisphere finds ‘nature is the best healer’