Severe floods and heavy rainfall have swept through south-east Queensland and northern New South Wales in recent weeks, killing at least 17 people and damaging thousands of homes and businesses. Through it all, engineers have been critical to the emergency response.
Engineers are involved in the entire lifecycle of natural disaster management. Even before a flood hits, engineers have an important role to play in flood prevention. When floods do occur, they monitor dam levels and, in the aftermath, they assess infrastructure and help to improve the management of future flood planning.
The recent flooding was caused by a slow-moving low pressure trough situated off the coast, which led to abnormally high rainfall across south-east Queensland and coastal New South Wales.
By the start of March, Brisbane’s three-day rainfall record had been broken, with the city recording 677 mm of rain. More than 15,000 homes were flooded.
The Brisbane River peaked at 3.85 m. Although this was lower than the 4.46 m recorded in 2011, the catchment area was much larger this time around, meaning more rain fell across a wider area.
Multiple towns have been impacted, including Lismore, which recorded its worst ever flooding on record.
Food and fuel shortages, once the domain of COVID-19 lockdowns, were also caused by the severe flooding.
Disaster management
According to Engineers Australia Fellow and Chartered engineer Marie Gales FIEAust CPEng, engineers are central to disaster management.
“Flood engineers and dam engineers are managing an almost impossible situation … but at the same time, there [are] other engineers who are looking at infrastructure,” she told create.
“Then, in the immediate aftermath there’ll be structural engineers … checking the ferry terminals, checking the bridges.”
Gales, who is the President of Engineers Australia’s Queensland Division, noted the role of engineers does not stop once the immediate threat to lives and infrastructure has passed.
“Once the recovery is over, we then get into the rebuild phase,” she said. “That’s a real opportunity for design engineers and constructors to … build back better.”
Engineers Australia Honorary Fellow and Chartered engineer Dr John Macintosh HonFIEAust CPEng agreed that engineers are critical to the effective management of natural disasters.
“The most important role [for engineers] is understanding what the problem is, designing a solution to solve or manage the problem, and then … creating the end product,” he said.
“That’s the case for engineers across the board. They’re trained to … break problems down and solve them in a logical and substantiated manner. Flood investigations and flood management are exactly that.”
Macintosh’s background in water engineering places him in good stead to assess the situation in Queensland and New South Wales.
“I don’t think we’ve ever had a situation in the Brisbane River catchment where rain has fallen for so long without moving,” he said. “[Or where] a rainstorm could extend for so long at fairly high intensity, directly placed over the Brisbane catchment.”
According to Macintosh, the challenge for dam operators is balancing three key elements: increasing dam storage levels, reducing the impact of flooding downstream, and avoiding loss of life.
Learning from the past
The floods in greater Brisbane are an unwelcome reminder of the disasters of 2011 and 1974. However, certain developments were made after those events that have greatly assisted in 2022.
“One of the learnings from ’74 was [that some of] the people who died … were electrocuted after the event,” Gales said. “So we have electrical engineers extensively monitoring the situation.
“Another key learning from the 2011 flooding was replacing the ferry terminals as pontoons broke free and became like missiles in the river. The ferry terminal gangways now break free to let debris through.”
Macintosh said there had been three major administrative and technical developments that have improved flood management and community resilience.
First is the Brisbane River Catchment Flood Study, which provided hydraulic and hydrologic assessments of the catchment system for the first time.
“That study connected Brisbane River from the city up to [Wivenhoe] Dam in a good hydraulic model,” he said.
Such modelling enables engineers to predict the effect of releasing excess water on flood levels downstream.
Secondly, reporting on the capacity of Wivenhoe Dam has also been improved. Now, regular water supply capacity is differentiated from flood storage capacity.
This has made it considerably easier for engineers to understand the complete picture during a high rainfall event, Macintosh said.
“The other thing is that they have increased the flood storage capacity from what it was previously,” he added.
Such changes echo the principle of taking on board new information and “melding it into our methodologies” to avoid the past being repeated, he said.
Both engineers agreed that a key way to do this is to build resilience.
“Part of the new design [of the Brisbane River] was about being flood resilient, not flood proof,” said Gales.
Building resilience
Engineers Australia Fellow and Chartered engineer Professor Cheryl Desha FIEAust CPEng sees the value of preventative measures and planning.
“Planning well for a range of potential scenarios [is essential],” she said. “In preparing for them, we are also likely to be preparing for the unknowns.
“Risk management tells us that we’re dealing with some unknowns that we can’t imagine yet.”
Desha, an environmental engineer and Griffith University academic, has been at the forefront of initiatives to build Brisbane’s resilience as a city.
For example, she was instrumental in the design of Griffith University’s Engineering, Technology and Aviation building, also known as Building N79, which can be adapted for use in different disaster contexts.
The building features laboratories, workshops and learning spaces for students, but it can also double as an emergency response centre — as evidenced by its recent use by the Red Cross.
“Wherever we are practising as engineers, we must return to the assumptions that we make about what we do and question them for their validity in a climate change-impacted world,” Desha said.
“For me as an academic, it extends into revising the curriculum that we are responsible for and making sure our students are equipped with what they need to perform … because the rules are changing.”
Macintosh agrees.
“With climate change there’s uncertainty about what might happen in the future,” he said. “We’ve got to become more resilient.”
Join us this November at the Hydrology & Water Resources Symposium as we discuss current water issues, including the recent NSW and QLD floods, and explore innovations shaping the future of water engineering. Submit your abstract by Friday 20 May to be considered for inclusion on the program. Find out more at hwrs.com.au
Excellent article. Is there a need to update ARR to account for the latest knowledge of climate change? I am guessing that we may need an ongoing regular revision and update to ARR as the impacts of climate change on rainfall become more apparent (ie as the science evolves). Accounting accurately for climate change in flood modelling and hydraulic design is vitally important.
I absolutely agree with you Adrian. Excellent comment. The article raises the issue of uncertainty about what lies ahead and I see this being used as a good reason to do nothing. I have researched Climate Change for a few years and developed a suite of engineering tools to predict various impacts as they apply to land development and associated infrastructure. What my algorithms show is absolutely frightening. Towns and cities of tomorrow will be nothing like what we have today. Large road and rail networks are a feature of the past – they will be prohibitively expensive to maintain. Location of population centres will also change, with selection criteria being based on security of energy, food and water; minimised impact from severe climate events (including “killer heat”, the first lethal impact we will need to grapple with); and accessibility from other population centres.
Today, engineers can devise ways to tweak the Brisbane River and its catchment, but at the end of the day the smart approach will be to let nature take its course (as it has done for millennia) and get everything important out of its way.
The most savvy Climate Change researchers indicate that our best efforts to reduce greenhouse emissions will only produce noticeable changes in the last two decades of this century, a position that is not being widely publicised. By Y2080 Rainfall Intensity will increase by 33% on average and the ARI 100y storm event will be roughly the equivalent of the historical ARI 1000y storm event.
Uncertainty stems from the complacency of humanity and the so called “tipping points” that form the gateway to runaway global heating. Nevertheless, there is already enough data available to make educated allowances for the points of uncertainty and do as you suggest – build them into ARR to get the ball rolling in the right direction for Design Engineers and Urban Planners.
Regular updates as new research data surfaces will be a given. I have been updating for a few years already.
So what is the average number of engineers that most councils have?
Flood waste and the involvement of engineers, is very important. Working around the clock to protect the environment and get the waste into facilities.
For years engineers have built bridges across waterways, but to save on cost of construction have built causeways (dams) across the floodplain from the high ground to the bridge.
Short term saving, long term cost.
If you got all the engineers together and got them to come up with a plan regarding flood mitigation nature is and will wash all of those plans as they say ‘down the drain’. You only have to look at where infrastructures have been built to see that a lot more information should have been sourced so that the damage as it is at the present time could have been alleviated. History shows us in many cases if the Indigenous community had been consulted ( but then they are not ‘qualified’ engineers) a large amount of nature’s damage could have been addressed or the damage happening now would have been reduced or eliminated. Indigenous people always have a firm grasp of what nature threw at them and I would not be surprised if they actually spoke to the so called experts in this field but in almost every case no notice was taken of them. The disappointing aspect is that it is still happening to this day.
Thanks Engineers Australia and contributors for a timely article. I agree with the importance of the contribution that engineers make in flood management and flood response but would like to see an expanded emphasis on the multi-disciplinary nature and the other elements of contemporary flood risk management. Engineers, urban planners, emergency services personnel, communications experts and others play a key role. Other dimensions of flood risk management include land use planning, development control, land management, infrastructure design for flood mitigation or flood resilience, communication and flood education. Collaborating with other key professional organisations such as the Planning Institute of Australia (PIA) and Floodplain Management Australia (FMA) is suggested on future advice to Government and guidelines.
The facts of engineering are:
Engineers and engineering consultancies work on commissioned projects.
Unless a client provides the necessary funding by way of commissioning a disaster mitigation/recovery project, the vast majority of engineers employed in private industry will not be employed on this type of work – it would have to be compared to doing pro bono work in the legal profession if they were.
Universities are now the places receiving the necessary funding from Federal and State Governments to provide mitigation solutions.
When Australia’s engineers all were relocated out of local authorities a vast amount of historical and technical knowledge regarding local conditions, floods, fires etc was lost to the local communities -all on the basis that these communities saved some money in rates for a short period of time.
It is now those same local communities that are bearing the unintended consequences of the past decisions.
I wonder if the temporal patterns of rainfall currently used for design adequately address Climate Change. As one of the previous comments noted earlier, perhaps there is some merit to a review of ARR; e.g. to utilise latest statistical methods to analyse rainfall gauging records in conjunction with meteorological modelling. And how are innovative minds in this space being rewarded (rather than companies)? Just some food for thought.
In weeks of TV reporting on the flooding in Qld and NSW I only saw one reference to an engineer – in respect of a temporary structure (in)stability in the Brisbane River.
I had the same thought.
Yes sure engineers construct dams for water storage and for flood control. (The construction Co. I worked for we raised the level of concrete wall to two dams. in NSW in 1986 and in WA in 2001). I was engaged for some technical assistance for a”rolled concrete” dam in Qld in 2003.
Read “Selling Queensland down the River” in Spectator. About river dredging , even 300-500 mm is significant to reduce flooding in flat plains. As is dredging river mouths. These were banned by Eco-Mayors and Qld State Governments.
Read another article “Rain Bom” re; the BOM’s mixture of incompetence to monitor the weather.
Re: Crohamhurst in Brisbane>
No mention by BOM simulation models for Qld (they are aligned with IPCC)
Or reminding Queensland Gov. that Crohamhurst in the Brisbane catchment on Feb 3rd 1893, recorded a 907mm rainfall over 24 hours, far more, nearly double, than floods of 1974, 2011, 2022,
No records kept or made available of all the natural climate cycles v rain.
Cheryl Desha blames the climate for changing-how dare the earth does that.
Disappointing that an engineer thinks/believes that earth’s climate never changes. (I suggest a read of Ian Plimer’s recent book for all)
Well we are enjoying possibly the best time ever, Coming out of the Little Ice Age (1300-1850) slowly at about 0.01C per yr (1.0C per 100 yrs). Going back to Roman and Medieval periods 800-1000, a few degrees warmer would be good! Unfortunately we are getting into 25th and 26th solar cycles, the Solar Physicist (DR Willie Soon) are say we should gear up for cold weather for a few decades.
And yes the climate was changing in 1893.
Perhaps legislating a requirement that all land sold for residential, industrial and commercial purposes in Australia be designated an average frequency of inundation, and that this advice together with likely once in 20 and 100 year flooding depths be provided to prospective purchasers would be a good start? This would allow all prospective buyers to do their own risk analysis. I would see the relevant Local Government Authority (LGA) responsible for providing the advice to prospective purchasers and the States being responsible for the funding and resourcing of the necessary studies to provide the advice. It would require a permanent commitment by State and LGAs to ensure details remain current in the light of continuing development. The impact of climate change could also be factored in to advice provided.
Governments and councils are the biggest problem with flooding.
Keeping creeks and rivers clear of vegetation and silt build up will give the the capacity to handle a higher water volume.
Building residential suburbs and industrial sites on flood Plains is another issue. It’s not called a flood plain for a reason.
Engineers can only do so much and are not always correct even with computer modelling.
No matter what strategy there is to curtail flooding the greed of government, councils and developers will ensure damaging flooding will continue
You cant pump the water back out to sea, you need to divert water into as many different river systems as you can so the water flows downstream to keep the other rivers alive and water flowing as it used to be. before modern times.
Mic, I couldn’t find any reference to ‘pumping systems in this article or in the discussions. I’d appreciate it if you could draw my attention any discussion / forum threads where engineering solutions where pumping solutions may have been suggested.