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National Flood Hazard Maps

The National Flood Risk Maps are based on generalised modelling created as part of Flood Risk Assessment Wales (FRAW) and published as part of Cycle 2 of the Flood Risk Regulations (2009).

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.

Acknowledgments

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.