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Long term flood risk maps


Use our maps to check your risk of flooding, explore in-depth flood risk information or look at the Development Advice Map to support a planning application. The links to each map are listed below.

If you need to download GIS data, many of the map layers can be downloaded from "Lle" the Welsh Government Portal for Open GIS data.

Basic Map View 

Check your long term risk of flooding from Rivers and Sea, Surface Water or Reservoirs.  Please note that the flood risk maps will only display when zoomed into community level and the flood source is ticked on. 

Detailed Map View

Intended for people, businesses or organisations who need to know more in-depth flood risk information about their area.  This provides further layers such as Flood Warnings, Shoreline Management Plans, Flood depth, velocity and hazard.  This may be to support a planning application, create a flood plan or just to find out more.

Development Advice Map

The Development Advice Map is for land use planning purposes.  It should be used alongside Planning Policy Wales and Technical Advice Note (TAN) 15 to direct new development with respect to flood risk.  Together, they form a precautionary framework to guide planning applications.

The map is based on Natural Resource Wales' extreme flood outlines (Zone C) and the British Geological Survey drift data (Zone B). Zone B data originally published 2004, updated in 2017, Zone C data revised quarterly. The online maps shown here are limited to a scale above 1:25,000 and not designed for small-scale investigations but as a trigger for policy advice in TAN 15. 


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 Centre for Ecology & Hydrology © NERC (CEH). Geological mapping: British Geological Survey © NERC. Defra and Met Office © Crown copyright. © Cranfield University. © James Hutton Institute. Contains OS data © Crown copyright and database right 2017. Land & Property Services © Crown copyright and database right.

Map descriptions

Risk of flooding from rivers and sea 

River flooding happens when a river cannot cope with the amount of water draining into it from the surrounding land. Sea flooding happens when there are high tides and stormy conditions. The shading on the map shows the risk of flooding from rivers and the sea in this particular area.

Flood alerts and warnings (detailed view)

In many areas we issue flood alerts and warnings for flooding from rivers and the sea. Select 'detailed view' on the map option to see areas that that can receive free flood warnings.​

  •  We issue flood alerts when flooding is possible.  If you receive a flood alert you should be prepared for flooding and to take action
  • We issue flood warnings to specific areas when flooding is expected.  If you receive a flood warning you should take immediate action

Floods can happen anywhere at any time.  Sign up for our free flood warning service and ensure you are prepared and know what to do when a flood happens.

Risk of flooding from surface water

Surface water flooding happens when rainwater does not drain away through the normal drainage systems or soak into the ground, but lies on or flows over the ground instead. 

The shading on the map shows the risk of flooding from surface water in this particular area.

Flooding from reservoirs (detailed view)

Reservoir flooding is extremely unlikely to happen.

Select 'detailed view' to see the layer for flooding that could occur from reservoirs. The shading on the map shows the worst-case scenario for the area that could be flooded if a large reservoir were to fail and release the water it holds. A large reservoir is one that holds over 10,000 cubic metres of water, equivalent to approximately 4 Olympic sized swimming pools.

The reservoir flood maps do not indicate any likelihood of a flood occurring.

Shoreline management plan 

The coloured lines represent preferred management approaches – or ‘policies’ – that are detailed in your local Shoreline Management Plan. 

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