UK Surface Water Flood Flow Direction at 3.3% Annual Chance

A GIS layer from the UK Environment Agency shows the dominant flow direction of surface water flooding at maximum speed for a flood with a 3.3% annual probability. The data is based on a 2-meter grid and groups flow into 8 compass directions. This dataset is part of the Risk of Flooding from Surface Water (RoFSW) mapping, previously known as the updated Flood Map for Surface Water.

Use Cases

• Modeling regional flood water movement based on the 2-meter grid flow direction data.
• Assessing surface water flood risk at a strategic scale based on the 3.3% annual chance event.
• Integrating flow direction data with other hydrological layers for composite flood mapping.

Strengths

• Data is based on a detailed 2-meter resolution grid.
• Flow direction is categorized into 8 specific compass bands.
• Produced by the UK Environment Agency with contributions from several authoritative organizations like the Centre for Ecology & Hydrology.

Limitations

• The record has been retired and superseded by another dataset.
• Explicitly not suitable for identifying flooding at individual property level.
• Description metadata is limited; actual data quality requires manual inspection after download.

Provenance

Source

Environment Agency (UK), with data licensed from the Centre for Ecology & Hydrology (NERC), Defra, Met Office, DARD Rivers Agency, Cranfield University, James Hutton Institute, and Ordnance Survey.

Collection Method

Likely derived from hydrological modeling as part of the Risk of Flooding from Surface Water (RoFSW) mapping.

Freshness

Last updated 2026-07-06 07:17:25.406237; freshness should be verified.

Geography

United Kingdom