WWNP Runoff Attenuation Features 3.3% AEP: Potential Flood Storage Sites in England

England's Environment Agency produced this geospatial dataset to identify potential locations for installing runoff attenuation features as part of natural flood management. It maps areas of high surface water flow accumulation for a 3.3% annual exceedance probability event, where temporary water storage could attenuate flooding. The data highlights ponding areas between 100 and 5000 square meters and tags opportunities for gully blocking on slopes steeper than 6%, excluding urban areas and major infrastructure.

Use Cases

• Prioritizing site surveys for runoff attenuation features based on mapped high-flow accumulation areas.
• Identifying potential locations for gully blocking interventions where ponding areas intersect slopes steeper than 6%.
• Strategic planning for natural flood management by excluding unsuitable areas like roads, rails, canals, and urban zones.
• Informing catchment-scale flood risk strategies by integrating with other Working with Natural Processes (WWNP) datasets.

Strengths

• Dataset is part of a formal government research project (SC150005) by the Environment Agency.
• Specific, quantitative criteria defined for feature identification (e.g., area 100-5000 m², slope >6%).
• Explicitly constrained to exclude urban areas, roads, rails, and canals to improve practical relevance.

Limitations

• Critical metadata is missing across all sources: column names, row count, file size, and license information are unknown.
• Data does not consider land ownership, changes in flood risk, or recent land use changes, which are crucial for implementation.
• Provides no information on engineering design requirements, such as drain-down between flood events.

Provenance

Source

Environment Agency (UK) via the Mapping Potential for Working with Natural Processes project (SC150005).

Collection Method

Derived from the Risk of Flooding from Surface Water datasets, identifying areas of high flow accumulation.

Freshness

2026-04-07 14:35:52.299831

Geography

England