National Flood Hazard Maps

Natural Resources Wales

National Flood Hazard Maps

The National Flood Hazard and Risk Maps are based on generalised modelling only. The maps have been published to comply with the Flood Risk Regulations (2009) and the EU Directive (2007/60/EC), and used to inform the creation of Flood Risk Management plans across Wales. These maps have no official status for Planning or Insurance purposes, therefore the public and professionals are advised to use the information contained within the Flood Risk Assessment Wales Map, the Development Advice Map/ Flood Map for Planning (as appropriate) for these purposes as these will be more up-to-date and incorporate improved modelling information.

The National Flood Hazard Maps have been created for 3 sources of flooding, namely,

  1. Flooding from Rivers
  2. Flooding from the Sea
  3. Flooding from Surface Water & Small Watercourse

The Maps show flood depth, velocity (speed and direction), hazard and extent for High, Medium and Low risk scenarios without raised flood defences.

For Rivers and Surface Water & Small Watercourses, High risk is up to 1 in 30year; Medium risk is between 1 in 30 and 1 in 100year; and Low risk is between 1 in 100year and 1 in 1,000year Annual Exceedance Probability (AEP).

For the Sea, High risk is up to 1 in 30 year; Medium risk is between 1 in 30 to 1 in 200 year; and Low risk 1 in 200 year to 1 in 1000 year.

The Flooding from Surface Water & Small Watercourses dataset is a direct replacement for the earlier Updated Flood Map for Surface Water (uFMfSW), 2013 and is based on the modelling of Surface Water Catchments.

Details of the modelling work to produce the new National Flood Hazard Maps are available in the supporting Information sheets.


Contains Natural Resources Wales information © Natural Resources Wales and database right. All rights reserved. Some features of this information are based on digital spatial data licensed from the UK Centre for Ecology & Hydrology © UKCEH, the Environment Agency © EA and Getmapping Plc and Bluesky International Limited [2015]. Defra, Met Office and DARD Rivers Agency © Crown copyright. © Cranfield University. © James Hutton Institute. Contains OS data © Crown copyright and database right. Land & Property Services © Crown copyright and database right.

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Flooding Spatial data

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Flood hazard raster data TIF