With heavy short-term rainfall events becoming more intense, it’s critical that Australia’s flood maps are dynamically altered to include the most up-to-date data, writes Chris Ryan.
In Australia, we’re dealing with a one-in-100-year flood far more frequently than once every century. Climate change undoubtedly has a hand to play. Evidence shows Australia has warmed by 1.5°C since national records began in 1910. The hotter the atmosphere, the more moisture it can hold. The result? More rain.
Since the beginning of 2025, there has been 19 flood- or storm-related incidents in Australia. For many parts of the country, flooding is now a common occurrence. Homes, businesses and farmlands are frequently being swallowed by angry torrents of water. According to the CSIRO and Bureau of Meteorology’s biennial report on the State of the Climate, heavy short-term rainfall events are becoming more intense. The question is no longer whether severe flooding events will occur. But how prepared we are to handle it.
As with any disaster, the first step is risk assessment. In flooding events, this is done through flood mapping. A flood map is a visual representation outlining areas more prone to flooding and where water usually accumulates during a severe weather event. These maps are crucial tools for understanding the risk of flooding and trying to plan response and mitigation strategies.
But most flood maps are out of date, drastically underestimating the impact climate change has on rainfall and risking lives and livelihoods. This was highlighted by the devastating floods that swept through New South Wales and Queensland in 2022, with the resulting destruction serving as a clear warning that state-wide guidelines needed to be updated to include the impacts of climate change.
Weather patterns we are trying to map are changing so rapidly.
Thankfully, the Australian Rainfall and Runoff organisation – which creates the guidelines for flood mapping – finally updated its requirements last year. What was previously thought of as a worst-case scenario – an annual rainfall increase of 20 per cent by the end of the century – is now a best-case scenario.
The reality is, the terrain and weather patterns we are trying to map are changing so rapidly that traditional modes of collecting and collating flood-related data can no longer keep up. We need to use live models that can be adjusted quickly and efficiently to reflect the changing environment.
For example, advanced technology, interfacing monitoring data and forecast data from BOM can simulate floods, which allows us to visualise and analyse a flood scenario. These can be adjusted within short time spans. Changes that would have previously taken significant time to alter, can now be adjusted to accurately predict and simulate inland and coastal flooding events.
After major floods swept through parts of Tasmania in 2016 and 2018, causing widespread damage to homes and communities, the road to recovery was long and cost millions of dollars. For many state and local governments recovery can overshadow the need for future pre-emptive planning and investment.
But the Tasmanian government and the federal government invested in a flood-mapping project to better understand the statewide flood risk and in doing so built resilience and support for future emergency response situations and recovery decision-making. Flood maps were updated using a strategic modelling environment, which used hydraulic and hydrodynamic models and collated a large volume of data on historic flood events to create a more accurate map.
The next severe weather event isn’t a what if – but a when.
In 2022, this was put to the test as record flooding headed towards the state. As the weather pattern moved through Tasmania, the model was used to forecast rainfall data and deliver predictive impact maps 12 hours before the rain started to fall. This greatly assisted operational response strategies, as well as public information warnings.
Accurate flood maps are beneficial to any Australian who may find themselves in the path of a severe weather system, as well as our emergency services and response and recovery teams. Not only should these models be replicated across Australia, but they need to be constantly reassessed as climate change swiftly adapts and affects our atmosphere.
For example, CSIRO’s guidance on rainfall intensity in Australia varies drastically depending on emissions, saying the intensity of daily rainfall with a one-in-20 year average recurrence may increase 4-10 per cent by 2050 for a low-emission scenario and 8-20 per cent by 2050 for a high-emission scenario.
The divergence between high- and low-emission outcomes is exactly why it’s critical that our flood maps must be dynamically altered to include the most up-to-date data on flooding events and weather patterns. If we keep putting off resilience projects investing in preparedness then rest assured we risk not learning from history and, worse, greater levels of destruction.
The next severe weather event isn’t a what if – but a when.
Chris Ryan, APAC Head of Water Infrastructure at Autodesk
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