Across Australia, experts point to an increase in extreme weather, including heavy short-term rain events. Yet decision makers working in utilities, planning and infrastructure are often ill-equipped with outdated flood-risk mapping.
Infoworks ICM is demonstating how it’s time to rethink the way Australia builds flood maps.
Since the beginning of 2025 alone, there have been 19 flood- or storm-related incidents in Australia. 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 them.
The release of the latest Australian Rainfall and Runoff (ARR v4.2) climate-change guidance only amplifies the urgency of the task to modernise our flood protection efforts. It calls on practitioners to account for more frequent occurrence of extreme rainfall intensities and their implications for catchment flooding.
Their updated guidelines promote the use of advanced digital and computational tools for more accurate flood risk assessments, and the guidelines encourage modellers to move from uniform to variable rainfall adjustments.
Utilising the latest cloud-based technology
Yet, many of our advisory tools – like flood maps – are sorely outdated, leaving decision-makers underprepared for the challenges that lie ahead. The problem is not simply one of intent, but of capacity. Updating flood models to reflect current conditions, let alone the projected impacts of climate change, has traditionally required significant time, resources, and computational effort.
This is where advances in technology are transforming what was once a monumental task into an achievable, scalable process. With the advent of cloud computing for hydraulic modeling in just the last few years alone, engineers can now use tools like InfoWorks ICM to build, calibrate, and run highly detailed hydrologic and hydraulic models much, much faster and more efficiently than ever before. What used to take days of computation can now be completed in hours or even minutes by running them parallel in the cloud.
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. And, these weather fluctuations will continue. For example, CSIRO’s guidance on rainfall intensity in Australia varies drastically depending on future 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.
To account for this future uncertainty and risk, as flood modellers we will need to model multiple scenarios – and keep adjusting our models. We may even need to go even deeper to reflect the changing climate and rely on live models that can be adjusted quickly and efficiently with piped-in BOM weather data.
No matter what, we will need to create larger and larger models to capture true-and-accurate catchment-wide effects, and we will need to present more and more options to our stakeholders so they can make the best, most data-informed decisions. All of this will require more computing power, which only the cloud may be able to provide.
Existing models put to the test
These kinds of extra-large catchment models already exist, and they can serve as an example for Australians – for example, in neighboring Tasmania.
After major floods swept through parts of Tasmania in 2016 and 2018, the Tasmanian government invested in a comprehensive 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 based on RAFTS + InfoWorks ICM which used hydraulic and hydrodynamic models and collated a large volume of data on historic flood events to create a more accurate map – they built one of the largest ICM maps available in Australia today.
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.
Wading through difficult waters
Obviously, the most important reason to update flood maps is to protect more lives and safeguard communities, and that was the big focus of the Tasmanian flood models. But there are other factors in the Australian flood equation – big financial factors. Recent research suggests that floods have caused a drop of $42.2B in the value of Australian homes.
When flood maps get updated, developers change direction, cancelling projects in some locations and investing in new ones elsewhere. Insurance companies adjust rates. Residents who have lived in one place their entire lives may wake up to find that their property now exists in a flood zone. These are some of the unexpected and unfortunate effects of climate change that governments and regulating bodies will have to increasingly grapple with – that they indeed are already struggling with.
Many of the arguments and considerations that come out of these struggles will hinge on finely-grained details of flood maps. Therefore, these flood maps will need to be as scientifically accurate as possible – and as defendable as possible. They will need to rely on the most accurate data available. They will also need to be easily and efficiently updated to consider multiple alternate scenarios. All of this can be made much easier by relying on high-tech tools that offer speedy, cloud-driven simulations.
Ultimately, modernising flood management in Australia requires a combination of updated science, forward-thinking policy, and the right technology. By embracing cloud-powered simulations and aligning with ARR’s climate change guidance, the industry has an opportunity to overcome the long-standing issue of outdated resources and deliver more resilient outcomes for communities.
