Seeing flood risk clearly: why better hazard data matters

We're seeing it happen again and again:  in 2011, floods struck Thailand's industrial heartland, disrupting global supply chains. When Hurricane Harvey hit Texas in 2017, surging floodwaters shut down critical energy infrastructure. And only last year, fierce floods across Europe and the Middle East caused near-record insured losses.

These tragic events, and many others like them, were more than costly catastrophes – they were a wake-up call. Extreme rainfall and storms drive destructive flooding that often outstrips experts' expectations, highlighting a broader challenge: water-risk data has long been patchy, outdated, or missing, obscuring the full scale of exposures.

After all, you can't manage what you can't see. Even regions with official flood maps face insufficient granularity or incomplete coverage. Perils are intensifying, too, as a warmer atmosphere fuels heavier rainfall and rising seas. In recent decades, economic development and urban expansion have put more valuable and vulnerable assets in risky areas.

Fortunately, we're making progress to address these challenges. Swiss Re has integrated flood-hazard data from Fathom, the water-risk intelligence company we acquired in 2023, into our proprietary tools including CatNet®, our natural-catastrophe insight platform, as well as our Portfolio Insights analytics solution and Risk Data & Services platform. With these, insurers, public-sector organisations, and corporate clients can run sophisticated flood hazard analyses based on additional data sources to better understand and reduce their exposures.

We've also begun incorporating Fathom's data into Swiss Re's internal flood risk models, establishing a consistent and transparent view across our underwriting and capital management activities. This will strengthen our scientific independence and ensure every decision, internal or client-driven, is guided by the same evidence-based understanding.

Fathom's peer-reviewed research is a benchmark for global flood modelling, transforming how flood risk in virtually every river basin and along every coastline can be understood and managed. By leveraging physically based global climate models, Fathom's data makes it possible to visualise depths for flood return periods ranging from 5 to 1,000 years.

As floods grow more frequent and severe with more extreme weather, traditional models can't keep pace. But with Fathom's Climate Dynamics framework, we can simulate how warming conditions and changing rainfall may alter these events under plausible scenarios through the end of the 21^st century.

With these foresights, governments can prioritise adaptation spending; insurers can expand in high-risk or underserved regions; and companies can strengthen their supply chains or select locations for their facilities with more confidence. Whether you're a data centre owner or renewable energy developer seeking safer sites or an urban planner aiming to protect your community, Fathom's water-risk intelligence helps mitigate flood risks before they materialise.

Fathom's data is already shaping real-world outcomes, supporting flood planning in Virginia and protecting public transport in Washington, D.C. In Australia and Canada, it informs emergency management and infrastructure design, while the Bank of England has used it to analyse flood risk. Fathom datasets also support Flood Re, the UK programme that supports insurance affordability including by helping flood-hit homeowners invest in defensive measures.

Floods are among the world’s costliest and deadliest natural hazards. A third of the global population is exposed, with flood-related economic losses exceeding USD 1.2 trillion in the past three decades. Every flood is unique, too, shaped by topography, land use, and volatile storms.

Even in many advanced economies, exposure data needed to anticipate the effects of torrential rains, rising rivers, coastal storms and changing weather has too often been limited. With the granular data that Fathom is making available on a global scale, however, it is now possible to capture important local nuances in greater detail.

For instance, when we compared Fathom models against those based on US regulatory maps, we discovered three times more people exposed to river flooding than the official estimates showed. Fathom's data doesn't simply indicate where there will be more water, either; it identifies higher, safer ground within flood zones, providing actionable intelligence to steer smarter development, not deter it.

Integrating Fathom's flood-hazard data into Swiss Re's core business represents an important step in helping us fulfil our purpose: to make the world more resilient.

Even though flood adaptation measures come at a price, Swiss Re has documented how they are up to 10 times more cost-effective than waiting until after a catastrophe, when rebuilding is the only option. And as adaptation grows in importance, Fathom's data can empower decision-makers to visualise risks so they can invest early where it matters most.

Since our company's founding in 1863, Swiss Re has evolved with the world’s shifting risk landscape. From modelling wildfires, earthquakes, hurricanes and hail, we continually refine how perils are understood, priced and managed. Our view of flood risk is changing, too – because we can now see it much more clearly.

With Fathom's data informing Swiss Re client tools and models, we're not just tracking water's destructive power; we're transforming how the world prepares for it. In risk, as in life, what you can see, you can manage. And what you can manage, you can make resilient.