Title

Properties at Risk of Flooding in Wales

Last update

September 2021 September 2021

Next update

Unknown

Publishing organisation

Welsh Government

Source 1

National Flood Risk Assessment data, Natural Resources Wales

Contact email

stats.environment@gov.wales

Designation

None

Lowest level of geographical disaggregation

Local authorities

Geographical coverage

Wales

Languages covered

English only

Data licensing

You may use and re-use this data free of charge in any format or medium, under the terms of the Open Government License - see http://www.nationalarchives.gov.uk/doc/open-government-licence

General description

The Flood Risk Assessment Wales (FRAW) together with the National Receptor Database (NRD) are used to determine the number of properties (residential and non-residential) at risk of flooding from rivers and sea in Wales.

Data collection and calculation

The chance of flooding is set out in three risk categories:

High Risk; Greater than or equal to 1 in 30 (3.3%) chance in any given year
Medium Risk; Less than 1 in 30 (3.3%) but greater than or equal to 1 in 100 (1%) chance in any given year for rivers and surface water flooding and less than 1 in 30 (3.3 per cent) but greater than or equal to 1 in 200 (0.5 per cent) for the sea.
Low Risk; Less than 1 in 100 (1%) for rivers and surface water flooding and 1 in 200 (0.5 per cent) for the sea but greater than or equal to 1 in 1,000 (0.1%) chance in any given year.

FRAW typically includes flooding from rivers with a catchment size greater than 3 square kilometres, and flooding from the sea (both along the open coast and tidal estuaries). Smaller watercourses are represented in the FRAW Surface Water data and maps with associated property counts.

The assessment takes into account the location and standard of protection afforded by flood defences and adjusts the risk categorisation accordingly from an initial, ‘undefended’ scenario. The likelihood of flooding and the consequent costs (economic damages) are assessed at an individual ‘receptor’ level and aggregated to 50m ‘impact’ cells.

Data reference periods

2019 onwards

Rounding applied

None.

Statistical quality

FRAW typically includes flooding from rivers with a catchment size greater than 3 square kilometres, and flooding from the sea (both along the open coast and tidal estuaries). Smaller watercourses are represented in the FRAW Surface Water data and maps with associated property counts.

The assessment takes into account the location and standard of protection afforded by flood defences and adjusts the risk categorisation accordingly from an initial, ‘undefended’ scenario. The likelihood of flooding and the consequent costs (economic damages) are assessed at an individual ‘receptor’ level and aggregated to 50m ‘impact’ cells.

Keywords

Flooding

Name

ENVI0211