dataset · Wales
Working with Natural Processes (WWNP) in Wales: Runoff Attenuation Features 3.3% AEP
Runoff Attenuation Features Potential is our best estimate of locations of high flow accumulation across the land surface or in smaller channels, where it may be possible to temporarily store water and attenuate flooding during high flows. The dataset is designed to support signposting of areas to target enhanced storage. It is based upon the Risk of Flooding from Surface Water datasets and identifies areas of high flow accumulations for the 3.3% Annual Exceedance Probability surface water maps.
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Licence: ["There are no access restrictions on this data. NRW may release, publish or disseminate it freely.", "\u00a9 CNC/NRW. Some features of this information are based on digital spatial data licensed from
Evidence quality: 45.9
Listed in data.gov.uk public catalogue API on 2026-10-16; relevance/value screened (haiku).
Metadata checked: 2026-10-14T13:20:00.000Z
What's in it
- Data offered docs-verified
- runoff attenuation features potential (locations of high flow accumulation) · ponding/accumulation areas of 100-5000 m2 (3.3% AEP surface water basis) · gully blocking opportunities (slope steeper than 6%)
- Coverage docs-verified
- Wales
- Resolution docs-verified
- Feature areas of 100-5000 m2 (ponding/accumulation areas); no raster cell size stated
- Update frequency docs-verified
- not planned
- Formats docs-verified
- WMS
- Access docs-verified
- Free and open; no access restrictions, NRW may release, publish or disseminate it freely. Entry licence text reads '© CNC/NRW' with third-party data attribution (truncated in entry).
Useful for
- Use cases llm-inferred
- Screening candidate areas for enhanced storage and natural flood management in Welsh catchment options appraisals · Identifying gully blocking opportunities on slopes steeper than 6% for flood attenuation · Signposting surface-water ponding and flow accumulation areas for FRA or drainage strategy context in Wales
- Audience llm-inferred
- flood risk consultants · hydrologists · drainage engineers · environmental consultants · GIS analysts
Limitations
- Constraints llm-inferred
- Signposting dataset for identifying areas; not a site-specific design or storage-capacity assessment · Based only on the 3.3% AEP surface water scenario · Potential areas exclude urban areas, roads, rails and canals · Updates not planned; dataset reference date is 2018-03-12 · Entry licence mentions third-party licensed spatial data; check attribution requirements
Evidence
- https://datamap.gov.wales/layers/inspire-nrw:NRW_WWWP_RUNOFF_ANTEN_3PC
- https://www.data.gov.uk/dataset/7a7c3a17-7723-44ef-b5a7-079a22135ab9/working-with-natural-processes-wwnp-in-wales-runoff-attenuation-features-3-3-aep2
Check upstream coverage, uncertainty and licence before use. Station observations are not forecasts or design levels.