National Reservoir Flood Extents for Wet Day Failure Scenarios

2026 data from the UK Environment Agency models the worst-case flood extents for large raised reservoirs in a 'wet day' failure scenario. The dataset represents a credible worst-case prediction, though it excludes smaller reservoirs and those commissioned after October 2016. It provides no indication of the likelihood or probability of such flooding occurring.

Use Cases

• Model downstream flood risk and emergency planning using predicted 'wet day' flood extents for large raised reservoirs.
• Analyze the spatial overlap of reservoir flood extents with existing floodplains or infrastructure for risk assessment.
• Compare worst-case flood extents for different large raised reservoirs across the national dataset.

Strengths

• Data is updated as of March 2026, ensuring recent modeling outputs.
• Models a specific and standardized 'wet day' failure scenario for consistent national comparison.
• Produced by the authoritative UK Environment Agency, a primary source for flood risk data.

Limitations

• Flood extents are not provided for smaller reservoirs, limiting comprehensive risk analysis.
• The modeling program excludes reservoirs commissioned after October 2016, creating a temporal data gap.
• The dataset explicitly provides no probability or likelihood data for the modeled flood events.

Provenance

Source

Environment Agency (UK)

Collection Method

Modeling program for reservoir failure scenarios, initiated in October 2016.

Time Range

Modeling program data from October 2016 onward; dataset reflects 2026 update.

Freshness

Last updated March 13, 2026.

Geography

National coverage for large raised reservoirs in the United Kingdom.