Amid the debris and devastation left behind by receding flood waters, there are questions that need answers and some important lessons to be learned.
Biblical, unprecedented, catastrophic
The sheer scale and intensity of the natural disaster that swamped South-East Queensland and northern New South Wales were astonishing – but could the flooding have been predicted?
That is the question on many minds – from shaken homeowners who awoke to find their homes filling with floodwater, to authorities dealing with crippling repair bills and extensive rebuilding.
Rivers in the sky and rain bombs
Flooding events like this are usually associated with cyclones, such as the widespread, devastating floods of 1974 and 2011. But not this time.
While Premier Annastacia Palaszczuk has blamed Queensland’s flood emergency on an "unpredictable rain bomb", it seems that the real culprit was more likely ‘rivers in the sky’.
"We need tools to predict when and where these atmospheric rivers might form again and what the outcomes might be.” Dr Adrian McCallum
“Technically, there is no such thing as a rain bomb,” says University of the Sunshine Coast Meteorologist and Civil Engineer Dr Adrian McCallum.
He says the recent intense rainfall and subsequent catastrophic flooding was caused by a poorly understood phenomenon known as an ‘atmospheric river’.
“The so-called ‘rivers in the sky’ in the lower atmosphere can exist across the tropical and sub-tropical regions.
“These rivers can transport high concentrations of water vapour inland, which as we saw, can result in record-breaking rain and catastrophic flooding when this low-level moisture-rich air is forced to rise, say by the Great Dividing Range.
“It is fascinating yet concerning stuff.
“This event was always going to be difficult to predict. What causes atmospheric rivers in Australia is still not exactly known and how they respond to climate change is not yet particularly understood.”
“The so-called ‘rivers in the sky’ in the lower atmosphere can exist across the tropical and sub-tropical regions.
“These rivers can transport high concentrations of water vapour inland, which as we saw, can result in record-breaking rain and catastrophic flooding when this low-level moisture-rich air is forced to rise, say by the Great Dividing Range.
“It is fascinating yet concerning stuff.
“This event was always going to be difficult to predict. What causes atmospheric rivers in Australia is still not exactly known and how they respond to climate change is not yet particularly understood.”
Is it time to put away the history ledgers?
No longer can people rely on reassurances that their houses had never been reached by flood water before.
As Queensland was inundated with seemingly relentless rain and our cities flooded, people drew on history to estimate heights and to see if they would be impacted, but was this the right approach?
Yes and no, according to UniSC History lecturer Dr Margaret Cook, who specialises in the history of natural disasters in Australia, especially floods and earthquakes, and is the author of “A River with a City Problem: A History of Brisbane Floods”.
“Historical knowledge about past floods can help us try to find patterns, particularly with river flooding, to predict where that water will go in normal rainfall events.
“But I think we're all in agreement that what we saw on the weekend was phenomenal rain which presented an insurmountable problem for modelling."
“Many were surprised when they were flooded this time but not in larger floods. Others were lucky and escaped this time after being impacted in other events.” Dr Margaret Cook
Dr Cook says floods and weather patterns seem to be changing, so perhaps the most important takeaway from this event is that no two floods are going to be the same.
“Rainfall location and intensity varies each time. Flow rates are affected by the dryness of the catchment, and creeks and rivers behave differently each time.
“We’ve also built in a lot of places that we've not lived in before, and so that's changing flood flows and just the number of people that are being impacted.
“Every tree cleared, and green space converted to housing estates, changes flood patterns and makes them harder to predict.”
Dr Cook discusses the wisdom of building on the banks of a flood- prone river and lessons from the history of flooding in two recent articles in The Conversation.
The blame game
Climate change, poor planning laws, or an uncontrollable, unpredictable natural force. Is it possible to attribute responsibility for the devastating flood emergency?
As the extraordinary weather event continued its destructive path south this week, international leaders on climate change issued a grim warning that global warming was going to result in more natural disasters in Australia and around the world.
UniSC Professor David Schoeman, an author on the latest Intergovernmental Panel on Climate Change report released on 1 March, says to expect more of the same.
"Among the simplest projections is that since warmer air carries more water vapour, we should expect intense rainfall events to shift from unusual events to being a fact of life.”
Professor David Schoeman
As the global climate warms, extreme weather events that rely on warm air will become more commonplace, says Professor Schoeman.
"Because of past inaction on climate change, planning for these events can no longer rely solely on cutting future emissions, we must also improve our planning and adapt to the impacts we know are coming.
These include not only more frequent intense-rainfall events, but also rising seas.
Working with nature to solve these problems will often be cheaper and work better than engineering “solutions” that depend on rubble and concrete.
"This is true for combating both floods and sea-level rise, among many other risks."
Is it fair to pin most of the blame on a changing climate?
Dr Schoeman says while climate change cannot be blamed for individual events, like the one we have just experienced, it does make such events more likely.
Human actions also change floods, according to Dr Margaret Cook.
“We need to think about our planning and ways that we can adapt our behaviour a little to try and mitigate these problems we've created,” Dr Cook says.
It is a sentiment supported by Dr McCallum who says the recent weather event is a reminder of our vulnerability and the need to more carefully consider where we approve construction and development.
“We really need to be careful about losing our memory collectively as communities, about where floodplains are historically.” Dr Adrian McCallum
“Because it's these times we realise perhaps we shouldn't be spreading into those areas where, traditionally, in these conditions, we can get large amounts of flood water.”
UniSC Lecturer in Environmental Engineering Dr Helen Fairweather says to manage flood risks in a changing climate, there is a need for climate-smart engineering to identify flood risks and mitigate future impacts.
Watery lessons
“While experts might not have predicted the exact scale and intensity, we should be preparing for the previously unimaginable.” Professor Claudia Baldwin.
There is much to unpack from this weather disaster and many lessons to be learned, according to Professor Claudia Baldwin, co-director of UniSC’s Sustainability Research Centre.
“We were warned that La Nina could produce a wetter season; it is difficult to predict exactly how and where it would happen. But we do know which rivers are flood-prone, and flood mapping is widely available on Council websites.”
Professor Baldwin says governments, emergency responders, businesses and residents should learn from previous and current events.
“The Queensland Flood Commission of Inquiry made many recommendations regarding flood modelling, river gauges, flood mapping, planning, and building controls.
“We have been asking for a report on how many of the recommendations have been implemented and how, and the status of those not implemented."
"This is critical to find out if we, and government, are taking the lessons learned seriously.” Professor Claudia Baldwin
Overwhelmed?
As the focus turns to the massive clean-up and recovery ahead, the emotional toll of this flood event will become more obvious. So what is the best way to cope or help friends, family and neighbours struggling after the flood?
UniSC Psychology academic Dr Sharman suggests trying to orient focus on the “problems” that need to be solved.
“What is it you can feasibly do or help with, such as remove a tree, clean the kids’ toys, get a tarp on the roof.
“If you are struggling with the sheer number of tasks, ask family and friends to help you brainstorm a priority list. Having said that, even chipping away at things that will need to be done is still valuable.
Maintaining a “problem-focused” goal setting approach tends to lead to better outcomes psychologically.
“If you are feeling completely overwhelmed: Stop. Breathe. And remind yourself that every mountain climb begins with the first small step.” Dr Rachael Sharman
As the mobilising people’s “Mud Army” proves with acts of kindness and generosity, natural disasters can be a time that brings out people’s altruistic side and draws neighbours and strangers together.
Dr Sharman said the most useful way to help someone is to provide practical and logistical assistance in the immediate term.
“For example, clean-up, offer alternative accommodation or help with transport, housing pets or dealing with insurance companies.”
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