Risk of Flooding from Surface Water

Natural Resources Wales

Risk of Flooding from Surface Water

This dataset has been superseded by the Surface Water & Small Watercourses component of the new “National Flood Hazard Maps” (2019) which can be found here (link to new products).

An archived version of the Risk of Flooding from Surface Water (2013) is available directly from Natural Resources Wales (opendata@cyfoethnaturiolcymru.gov.uk).


The surface water flood maps give an indication of the broad areas likely to be at risk of surface water flooding.  This includes flooding that takes place from the 'surface runoff' generated by rainwater (including snow and other precipitation) which:

(a) is on the surface of the ground (whether or not it is moving), and
(b) has not yet entered a watercourse, drainage system or public sewer.

The Flood Map for Surface Water pick out natural drainage channels, rivers, low areas in floodplains, and flow paths between buildings. But it does not indicate flooding caused by local rainfall.  It does not show flooding that occurs from overflowing watercourses, drainage systems or public sewers caused by catchment-wide rainfall events or river flow.  A national model has been run for 1 in 30, 1 in 100 and 1 in 1000 year rainfall events. Lead Local Flood Authorities were consulted and where available locally held model outputs have been incorporated into the maps.

Attribution statement

© CNC/NRW and Centre for Ecology & Hydrology © NERC (CEH)
Some features of this information are based on digital spatial data licensed from the Centre for Ecology & Hydrology © NERC (CEH). Defra, Met Office and DARD Rivers Agency © Crown copyright. © Cranfield University. © James Hutton Institute. Contains OS data © Crown copyright and database right 2015. Land & Property Services © Crown copyright and database right

See metadata

Appears under
Flooding Spatial data

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