Fathom-UK
Flood Hazard
Data

Comprehensive flood modelling for
the whole of the United Kingdom

Introduction Fathom-UK offers an alternative view of flood risk in the UK. Using a combination of world-leading research and cutting edge modelling techniques, we are able to accurately simulate UK flood hazard for both current and future climate scenarios.

Product key features

01

10 meter resolution.

02

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

03

5 climate scenarios across 3 time horizons – Utilising UKCP18 climate data to produce scenarios for present day, 2030, 2050 and 2070.

04

Fluvial, pluvial & coastal – Assess the impact of multiple flood types.

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Terrain data – Incorporates the latest LiDAR data, in addition to other terrain and hydrography datasets.

06

Defences – Unique detection algorithm that identifies flood defences where data are not available.

About the model and validation Created by some of the world’s leading academics and scientists in the field of climate risk and hydrology, Fathom-UK is based on pioneering methods that have been developed in-house.

Underpinned by decades of peer-reviewed research, our model couples a decades of scientific research with the latest hydraulic modelling techniques.

The result is accurate flood hazard data that is able to provide high-resolution predictions for both current and future climate scenarios – a first for flood modelling in the UK.

By integrating these datasets into Fathom’s hydraulic modelling framework, Fathom-UK yields flood hazard maps of multiple return periods for every river in the country.

This has been achieved through Fathom’s unique channel estimation methods, which explicitly represent river channels in the absence of accurate hydrographic information.

When incorporated alongside precise terrain data, multiple perils and defence algorithms, users are presented with accurate and realistic patterns of flood inundation.

Model features Model features

    Pluvial flood Fathom-UK’s pluvial model accounts for drainage systems, flash flooding and infiltration across a variety of terrain.

    01

    100% coverage of the United Kingdom.

    02

    10m resolution nationwide.

    03

    Channel drainage is explicitly represented.

    04

    Flooding simulated for even the smallest flow pathways.

    05

    Extreme precipitation magnitudes using data from UK Centre for Ecology and Hydrology (CEH).

    06

    Multiple return periods.

    1 in 100 year pluvial flood simulation of Reading, UK.

    Fluvial flood Our fluvial model can accurately represent extreme river flows at any point for every UK river.

    01

    10m resolution nationwide.

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    Channels explicitly represented.

    03

    100% coverage of the United Kingdom.

    04

    Flows based on the entire NRFA gauge record.

    05

    Multiple return periods.

    06

    Comprehensive defence representation.

    1 in 1000 year fluvial flood simulation of Nottingham, UK.

    Coastal flood We account for multiple coastal scenarios including sea level rise, high tides and storm surge.

    01

    100% coverage of the United Kingdom’s coast.

    02

    10m resolution nationwide.

    03

    Channels explicitly represented.

    04

    Extreme water level scenarios taken from the Environment Agency

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    Multiple return periods.

    06

    Tide gauge data and wave setup estimates based on ECMWF.

    1 in 100 year undefended coastal flood simulation in Avonmouth, under a 2070 climate scenario.

    Research and validation Research and validation

      01 Climate change is altering the way that we experience events.

      By 2050, over 1.3 million properties in Great Britain will be at risk of substantial flooding. Our data provides the right people with the correct information – so that they can mitigate risk.

      Fathom-UK helps to quantify flood risk and asset exposure for 5 climate scenarios, acrss 3 time horizons. This is the first flood model in the UK to factor in the impact of climate change, rather than just relying solely on historic records. By doing so, Fathom takes the UK’s understanding of flood risk one step further and supports users to understand how risk will change over time.

      With new regulation requiring insurers, corporations and risk managers to have a greater understanding of flood risk in the future, our model provides accurate predictions for pluvial, fluvial and coastal perils. Fathom-UK’s inclusion of 10 return periods means that users have access to a wide collection of event frequencies.

      The hydraulic model projects changing flood behaviour arising from UKCP18.

      Model validation Fathom-UK is validated against EA, Northern Ireland EA, Scottish Environment Protection Agency, and Natural Resources Wales flood data.

      Comparison against a Fathom (blue) 1-in-100 year flood simulation of Reading to EA data (red). Comparison of our model has found that our work measures accurately against these data.

      03 Fathom-UK builds on a body of research, data and methodologies that spans over two decades.

      Bates et al (2021) is a significant paper reviewing our approach to future flood risk and coastal modelling. Published in Water Resources Research, the paper found that:

      – Comparison against data from the Iowa Flood Center indicates considerable model skill in simulating both high and low-frequency events.

      – Our national model simulated pluvial flooding within areas that FEMA did not. This identified a further 28 million citizens who were exposed to the 100-year flood.

      We will be publishing a similar paper on Fathom-UK in 2022.

      Relevant research

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      Research Paper

      A simple inertial formulation of the shallow water equations for efficient two dimensional flood inundation modelling

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      Research Paper

      Distributed whole city water level measurements from the Carlisle 2005 urban flood event and comparison with hydraulic model simulations

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      Research Paper

      Evaluating the effect of scale in flood inundation modelling in urban environments

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      Research Paper

      Reach scale floodplain inundation dynamics observed using airborne Synthetic Aperture Radar imagery: data analysis and modelling

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      Research Paper

      An initial comparison of two 2-D finite element codes for river flood simulation

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      Research Paper

      Modelling floodplain flows using a two-dimensional finite element model