Fathom-US 2.0 Flood Hazard Data

A paradigm shift in our understanding of US flood hazard

Introduction Fathom-US 2.0 provides the most comprehensive view of flood hazard across the United States and is based on the latest science and datasets. For anybody seeking to understand US flood exposure, Fathom-US 2.0 is the complete picture.

Product key features

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Climate change — Updated 2020 climate state.

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10 return periods – Ranging from 1:5 year to 1:1000 year. Return periods can be categorised to suit your risk appetite.

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Coverage

  • Fathom covers 100% of contiguous US
  • FEMA covers 60% of contiguous US
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Flood defences — Most complete flood defence dataset built with input from multiple agencies. Independent validation of levee information.

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Inland flooding — Total representation of fluvial and pluvial flooding. Simulation of flooding for all river channels, irrespective of size, from smallest to largest.

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Resolution — 10m resolution.

About the model and evolution Fathom have partnered with world leading scientists to undertake the most comprehensive flood modelling of the United States ever attempted.

Our 2020 simulations provide an updated view on today’s risk; basing models on historical observations alone is likely to underestimate exposure.

Fathom-US 2.0 provides projections of fluvial flood inundation at 10 meter resolution for every river channel in the US. The result is a model that offers users a detailed and in depth understanding of flood risk, so that they can inform their business processes with confidence.

Model features Inland flood models are based on the latest US government terrain and river data.

    Fathom-US 2.0 fluvial models cover every watercourse from the largest river down to the smallest stream.

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    10m resolution nationwide.

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    Channels explicitly represented.

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    100% coverage of the contiguous US.

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    Flows derived from US Geological Survey river gauges.

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    Multiple return periods.

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    Comprehensive defence representation.

    Pluvial models Fathom’s pluvial models represent flash-flooding nationwide.

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    10m resolution nationwide.

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    Channel drainage is explicitly represented.

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    100% coverage of the contiguous US.

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    Flooding simulated for even the smallest flow pathways.

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    Extreme precipitation magnitudes from NOAA.

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    Multiple return periods.

    Fathom-US 2.0 Launch Webinar

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    Fathom delivered high-quality and timely analyses to improve the global flood hazard classification in ThinkHazard!, and helped make the data available for disaster risk management activities in developing countries.

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    Fathom’s powerful models are uniquely able to support our work evaluating potential nature-based solutions at large scales. Working with them has been great – they are highly skilled professionals who have delivered products on time throughout every phase of our work.

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    Aon and Impact Forecasting can now more holistically approach clients’ flood risk management and quantification needs thanks to our collaboration with Fathom.

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    Fathom provided a first-rate product and service based upon cutting-edge research and methodologies, which are both robust and transparent. Their flood data sets are global, consistent and high calibre. Most importantly, Fathom-Global is a responsive and collaborative firm who consistently deliver.

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    I’d like to thank the effort of regional flood planning groups, its members, technical consultants, the public and other agencies who have been putting in a lot of time to put together regional flood plans, essentially going to come together as the first State Flood Plan for Texas.

    Research and validation Fathom-US 2.0 has been subjected to an unprecedented level of independent validation.

      01 Fathom’s work has proven that current methods significantly underestimate flood risk.

      FEMA’s flood hazard data are a patchwork of small scale ‘traditional’ flood models.

      In many areas these models are outdated, with some dating back to the 70s and 80s.

      Currently 75% of these maps are deemed to be out of date and 40% of the country hasn’t even been covered.

      02 Collaborative work with the US Environmental Protection Agency suggests a 3 fold increase in total flood exposure to a 100 year flood.

      FEMA have identified 13 million Americans exposed to 100 year flood (light blue).

      In contrast, Fathom’s model has identified 41 million Americans exposed to 100 year flood (dark blue).

      Research conducted in collaboration with Bradt and Kousky (2021) found that voluntary insurance purchases are preferentially taking place in areas where Fathom’s model deviates from FEMA flood maps. This implies that our model is correctly identifying areas of risk which FEMA’s model misses.

      Independent validation Fathom-US 2.0 has been subjected to an unprecedented level of independent validation.

      Firstly, Fathom has undertaken award-winning validation work comparing models against FEMA flood hazard data, where they exist. As well as this, its methodologies have been examined within a peer-reviewed research paper, published in Water Resources Research:

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      Research Paper

      Combined Modeling of US Fluvial, Pluvial, and Coastal Flood Hazard Under Current and Future Climates

      Climate Change Research Climate Change is anticipated to alter many of the Earth’s weather patterns, including extreme temperatures, precipitation and hurricane intensity.

      Academic research suggests this will have a noticeable impact on the lives of those living within the US.

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      Research Paper

      Attributable human-induced changes in the magnitude of flooding in the Houston, Texas region during Hurricane Harvey

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      Research Paper

      Flood exposure and social vulnerability in the United States

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      Research Paper

      Combined Modeling of US Fluvial, Pluvial, and Coastal Flood Hazard Under Current and Future Climates

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      Research Paper

      Estimates of present and future flood risk in the conterminous United States