Risk of Flooding from Surface Water (RoFSW) map is an assessment of where surface water flooding may occur 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. It includes information about flooding extents and depths. It is produced using national scale modelling and enhanced with compatible, locally produced modelling from lead local flood authorities (LLFAs).

RoFSW is a probabilistic product, meaning that it shows the overall risk, rather than the risk associated with a specific event or scenario. In externally published versions of this dataset, risk is displayed as one of three likelihood bandings:

High - greater than or equal to 3.3% chance in any given year (1 in 30)
Medium - less than 3.3% (1 in 30) but greater than or equal to 1% (1 in 100) chance in any given year
Low - less than 1% (1 in 100) chance in any given year

NB. This is a complex dataset, with preview available only on certain zoom levels. The Web Mapping service has been set to 1:50 000 in the

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) that: (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. It has been modelled on a 2 metre square grid. Lead Local Flood Authorities were consulted and where available locally held model outputs have been incorporated into the maps. This dataset has been superseded by the new National Flood Hazard Maps 2019 - NRW_DS124790

Risk of Flooding from Surface Water (RoFSW) map is an assessment of where surface water flooding may occur 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. It includes information about flooding extents and depths. It is produced using national scale modelling and enhanced with compatible, locally produced modelling from lead local flood authorities (LLFAs).

RoFSW is a probabilistic product, meaning that it shows the overall risk, rather than the risk associated with a specific event or scenario. In externally published versions of this dataset, risk is displayed as one of three likelihood bandings: High - greater than or equal to 3.3% chance in any given year (1 in 30) Medium - less than 3.3% (1 in 30) but greater than or equal to 1% (1 in 100) chance in any given year Low - less than 1% (1 in 100) chance in any given year

This dataset presents the risk which takes account of the following climate change allowances based on the latest UK Climate Projections (UKCP18) from the Met Office, using the Representative Concentration Pathway (RCP) 8.5:

- the ‘Central’ allowance for the 2050s epoch (2040-2060) for risk of flooding from surface water.

These allowances include anticipated changes to peak rainfall intensity.

NB. This is a complex dataset, with preview available only on certain zoom levels. The Web Mapping service has been set to 1:50 000 in the