How new modelling approaches enhance insight into a changing risk environment
As flood patterns in Australia become more unpredictable, insurers and policy makers must evolve how they understand, assess, and manage risk.
Unprecedented rainfall is affecting regions once considered lower risk. Localised flooding is increasingly driven by non-cyclonic weather systems – events that are harder to predict and model. Cities are expanding into floodplains, and climate change is redrawing the boundaries of exposure. What was once a seasonal hazard is now a year-round concern – driven by increasingly variable weather, expanding urban development, and growing uncertainty around how flood events will unfold. For those tasked with managing risk, the challenge is not just about understanding where flood might happen – but when, how, and with what consequences.
In March 2025, Outback Queensland experienced devastating flooding after prolonged rainfall from a slow-moving trough that overwhelmed local catchments. The impact was widespread – displacing families, damaging infrastructure, and triggering insurance losses in places not traditionally seen as high-risk.
Just weeks earlier, ex-Tropical Cyclone Alfred made landfall further east. It proved to be a rare Gulf cyclone that deviated from its expected track, hitting Brisbane head-on and highlighting how flood risk can arise from very different meteorological sources – even within the same season.
These events raise questions we hear often: where will the next flood happen –and how bad could it be?
Capturing complexity: why inland flood modelling matters
JBA’s new Australia Inland Flood Model is the latest step in helping both the insurance and public sectors navigate flood risk in a more detailed, dynamic way. It determines losses from flooding by taking into account complex interactions between hazard and exposure components.
Built using a combination of physical and statistical methods, the model simulates nearly 350,000 hydrological events, from widespread tropical and non-tropical cyclones to small, localised bursts of rainfall that can still cause significant damage. These localised events are often missed in broader risk assessments, yet they represent a growing share of losses in Australia.
By incorporating flood defence data, terrain, and land use, the model captures how water flows around properties – not just over a catchment map.
Science for a changing climate
The model builds on JBA’s established foundation of high-resolution flood data – already widely used across the Australian insurance market – to provide a consistent view of flood risk across underwriting, portfolio management, and regulatory planning.
For insurers, reinsurers, and policymakers, this isn’t just about numbers – it’s about planning. What will portfolio exposure look like in 25 or 50 years? How should capital reserves evolve? Where might investment in adaptation or managed retreat be most needed?
The model’s ability to project flood risk under future climate scenarios supports more informed, long-term decision-making.
Using RCP4.5 and RCP8.5 pathways for 2050 and 2080, it shows how risk levels may shift as rainfall patterns change and extreme weather becomes more frequent.
It also includes uncertainty and sensitivity tools – enabling users to explore these questions from multiple angles and make decisions grounded in the best available science.
Want to explore more?
You can read about how the March 2025 Outback Queensland floods are challenging assumptions about where risk lies in our event response blog.
Or if you're interested in the Australia Inland Flood Model or would like to discuss a specific scenario, contact us.