Properties at Risk of Flooding
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- High level information
- Summary information
- Statistical quality information
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Title
Properties at Risk of Flooding in WalesLast update
September 2021Next update
UnknownPublishing organisation
Welsh GovernmentSource 1
National Flood Risk Assessment data, Natural Resources WalesContact email
stats.environment@gov.walesDesignation
NoneLowest level of geographical disaggregation
Local authoritiesGeographical coverage
WalesLanguages covered
English onlyData 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-licenceData reference periods
2019 onwardsRounding applied
None.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.
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.
