Introduction Fathom’s US Flood Map, Fathom-US, 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 is the complete picture
Product key features
Climate change — Updated 2020 climate state.
10 return periods – Ranging from 1:5 year to 1:1000 year. Return periods can be categorised to suit your risk appetite.
Coverage
- Fathom covers 100% of contiguous US
- FEMA covers 60% of contiguous US
Flood defences — Most complete flood defence dataset built with input from multiple agencies. Independent validation of levee information.
Inland flooding — Total representation of fluvial and pluvial flooding. Simulation of flooding for all river channels, irrespective of size, from smallest to largest.
Resolution — 10m resolution.
About the model and evolution Fathom have partnered with world leading scientists to undertake the most complete view of US flood hazard 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’s US Flood Map 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.
For fluvial, Fathom’s US Flood Map covers every watercourse from the largest river down to the smallest stream.
10m resolution nationwide.
Channels explicitly represented.
100% coverage of the contiguous US.
Flows derived from US Geological Survey river gauges.
Multiple return periods.
Comprehensive defence representation.
Pluvial models The pluvial component of the hazard map represents flash-flooding nationwide
10m resolution nationwide.
Channel drainage is explicitly represented.
100% coverage of the contiguous US.
Flooding simulated for even the smallest flow pathways.
Extreme precipitation magnitudes from NOAA.
Multiple return periods.
01 Fathom’s work has proven that current methods significantly underestimate flood risk
In many areas these models are outdated, with some dating back to the 70s and 80s.
Currently 75% of these maps are deemed to be out of date and two thirds of the rivers in the United States are not modelled by FEMA (ASFPM, 2020).
02 Collaborative work with the US Environmental Protection Agency suggests a 3 fold increase in total flood exposure to a 100 year flood
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 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:
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
Attributable human-induced changes in the magnitude of flooding in the Houston, Texas region during Hurricane Harvey
Flood exposure and social vulnerability in the United States
Combined Modeling of US Fluvial, Pluvial, and Coastal Flood Hazard Under Current and Future Climates
Estimates of present and future flood risk in the conterminous United States
