FATHOM US

Fathom-US 2.0 provides the most comprehensive view of flood hazard across the United States and is a unique combination of pluvial and fluvial flooding based on the latest science and datasets.

For anybody seeking to understand US flood exposure, Fathom-US 2.0 provides the complete picture.

Please contact us if you would like to know more about Fathom-US 2.0.

10 metre resolution

10 return periods from
1:5 years to 1:1000 years

Climate
change

Updated 2020
climate state

Flood
defences

Most complete flood
defence dataset built
with input from multiple
agencies. Independent
validation of levee
information

return periods

From 1:5 year to 1:1000 year.
Return periods can be categorised to suit your risk appetite.

Inland
flooding

Total representation of
fluvial and pluvial flooding.
Simulation of flooding
for all river channels,
irrespective of size, from
smallest to the biggest

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

Fathom have partnered with world leading scientists to undertake the most comprehensive modelling of the United States ever attempted.

Both the inland and coastal flood hazards have been modelled under a 2020 climate scenario and are not based solely on historical records.

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 and pluvial flood inundation at 10 metre 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.

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

10m resolution nationwide.

Channels explicitly represented.

100% coverage of contiguous US.

Flows generated from entire USGS gauge record.

Multiple return periods.

Comprehensive defence representation.

Comparison of a remotely sensed Midwest flood event with Fathom fluvial data -

Planet data

Surface water

Comparison of a remotely sensed Midwest flood
event with Fathom
fluvial data -

Fathom-USv2
fluvial hazard data

0.5m

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

Fathom’s pluvial
models represent
flash-flooding
nationwide

10m resolution nationwide.

Channel drainage explicitly represented.

100% coverage of contiguous US.

Flooding simulated for even the smallest flow pathways.

Extreme precipitation magnitudes from NOAA.

Multiple return periods.

Representing flood defences
is critical, however existing
defence datasets are
substantially incomplete

Undefended

Defended

To help address this key issue, Fathom funded a PhD resulting in the development of an automated flood defence detection algorithm.

Fathom have built out the most complete flood defence dataset built with input from multiple agencies and independently validated.

This has included a collaboration with the US Army Corps of Engineers and a dedicated levee development team.

This team spent over a year focusing solely on sourcing missing levee, dam and storm water infrastructure information from across the US which have been included in Fathom-US 2.0, creating the most complete dataset currently available.

Fathom are now working with FEMA and the US Army Corps of Engineers to update their levee databases.

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

FEMA capture
major rivers only

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.

Fathom-US
captures all
river channels

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

Fathom-US 2.0 was measured against the entire FEMA flood hazard catalogue, identifying that current FEMA data misses around three quarters of total flood exposure nationwide.

According to FEMA, 13 million Americans are exposed to risk from the 100 year flood. Fathom data suggests differently.

FEMA identified 13 million Americans are exposed
to 100 year flood

13M

Unlike FEMA data, Fathom's accurate, peer-reviewed research has found that 41 million Americans are at risk from a 100 year flood event.

Fathom identified
41 million Americans are exposed to 100 year flood

41M

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

Firstly, the methods build on Fathom’s award-winning validation work comparing models against FEMA flood hazard data, where they exist.

Next, the Fathom models have been compared to high-quality, multi-million-dollar models from the Iowa Flood Center.

Lastly, Fathom-US has faced unprecedented validation by the academic community. Its methodologies have been examined within a peer-reviewed research paper, published in Water Resources Research.

Academic validation

Read Paper

Validation of Fathom-US flood hazard model

Water Resources Research, 2017

Press

Cool Green Science

New Study Shows Flood Risks Across the U.S. are Underestimated
(in a Big Way)

Press

BBC News

US flood risk 'severely underestimated'

Press

Science Daily