Ex-Cyclone Alfred has left flooding in its wake. Here’s how floods affect our health
- Written by: Jodie Bailie, Senior Research Fellow, The University Centre for Rural Health and The Centre for Disability Research and Policy, University of Sydney
Ex-Cyclone Alfred is bringing significant rainfall to southeast Queensland and the Northern Rivers of New South Wales. Flooding has hit Lismore, Ballina, Grafton, Brisbane and Hervey Bay, which received 150 mm of rainfall in two hours this morning.
Tragically, a 61-year-old man died after being swept away in floodwaters near Dorrigo in northern New South Wales.
More heavy rain and flash flooding is expected in the coming days as the weather system moves inland and weakens.
Climate change is making these weather events more intense and frequent. Earlier this year, far north Queensland experienced major flooding. As residents of the Northern Rivers, this latest disaster is especially tough because only three years ago we faced the catastrophic 2022 floods.
We’ve studied the impact of floods on human health and wellbeing, and found floods are linked to a range of physical and mental health effects in both the short- and long-term.
So what might you experience if you live in an area affected by these floods?
We reviewed the evidence
We recently reviewed research on the physical and mental health impacts of floods across mainland Australia. We included 69 studies in our review, published over 70 years. The majority were from the past ten years, examining the effects of floods in Queensland and NSW.
These studies suggest people can expect a range of health impacts. Immediate physical health effects of floods include drowning, falls and injuries.
Chronic diseases such as diabetes or renal disease can also worsen due to factors such as reduced access to transport, health-care services, medications and hospitals.
Exposure to contaminated floodwaters can lead to skin infections, while respiratory problems can occur due to mould and damp housing in the aftermath of floods.
Floods also create ideal conditions for mosquito borne infections such as Ross River virus and Murray Valley encephalitis, while also spreading infectious diseases including leptospirosis, a bacterial infection from contaminated soil.
Read more: Don't go wading in flood water if you can help it. It's a health risk for humans – and dogs too
There are mental health consequences too
Our review showed floods also affect mental health. The more you’re exposed to floodwaters in your home or business, the worse the mental health impacts are likely to be.
The After the Flood study examined mental health and wellbeing outcomes six months after the 2017 flood in the Northern Rivers. It found people who had floodwater in their home, yard or business, or who were displaced from their home for a more than six months, were much more likely to have probable post-traumatic stress disorder, anxiety or depression, compared to those who didn’t experience flooding or weren’t displaced.
Repeated natural disasters could compound these mental health consequences. Southeast Queensland and the Northern Rivers in NSW have experienced multiple disasters over recent years. The Northern Rivers faced major flooding in 2017, bushfires in 2020, further major floods in 2022, and now Cyclone Alfred in 2025. These repeated disasters have taken a toll on our community, creating a seemingly never-ending cycle of recovery, rebuilding and preparation for the next disaster.
Our understanding of the unique challenges faced by communities which experience multiple disasters is still growing. However, a recent Australian study showed exposure to repeated disasters has a compounding effect on people’s mental health, leading to worse mental health outcomes compared to people who experience a single disaster.
Mums and babies
The health effects of floods extend far beyond the initial emergency and beyond the infections and mental health consequences you might expect.
The Queensland Flood Study tracked pregnant women exposed to the 2011 Brisbane floods. Researchers assessed mothers’ stress related to the flood and tracked them and their children at six weeks old, six months, 16 months, 2.5 years, four and six years. It found some links between prenatal stress and developmental outcomes in children.
While the health effects after flooding are diverse, the research to date is not comprehensive. We need to learn more about how floods contribute to or exacerbate existing chronic illnesses, disability and long-term mental health issues.
The impacts are inequitable
Flooding exposes and worsens existing inequalities. Socially vulnerable groups are more likely to be exposed to flooding in their homes and have less access to resources to respond and recover from these events, putting some groups at higher risk of negative health impacts afterwards.
Some research has looked at the disproportionate impacts on people with disabilities and their carers, First Nations communities and people from disadvantaged backgrounds.
After the 2017 Northern Rivers floods, for example, people with disability and their carers were more likely than others to:
- experience disrupted access to food, support networks and essentials such as health care and social services
- continue to be distressed about the flood six months after it happened
- be at relatively high risk of post-traumatic stress disorder six months after the flood.
However, targeted flood research exploring the experiences of these vulnerable groups in Australia is limited.
Moving forward, it’s vital we examine the varied impacts of flood events for more vulnerable groups, so we can better support them in the wake of devastating events such as Cyclone Alfred.
If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.
Read more: Returning home after a flood? Prioritise your health and take it one step at a time
Authors: Jodie Bailie, Senior Research Fellow, The University Centre for Rural Health and The Centre for Disability Research and Policy, University of Sydney
