dataset · Wales
Internal Drainage Districts (IDD)
Drainage districts are typically found in low-Iying land where boundaries are determined by physical, not, political attributes. Districts vary in nature and size, from the mainly agricultural (such as Conwy, Llanfrothen and Towyn) to the semi-urban (such as the Gwent Levels). Drainage districts are at risk from various sources of flooding. Without flood risk and water level management, drainage districts would be unsuitable to live in and would not protect and provide for the variety of agricul
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Licence: ["There are no access restrictions on this data. NRW may release, publish or disseminate it freely.", "\u00a9 CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is
Evidence quality: 51.4
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
- IDD boundaries (Wales) · maintained watercourses · tidal flaps · pumping stations · sluices (Caldicot & Wentlooge Levels & Lower Wye and Powysland only)
- Coverage docs-verified
- Wales
- Update frequency docs-verified
- unknown
- Formats docs-verified
- WMS (Web Mapping Service)
- Access docs-verified
- Free and open: no access restrictions; NRW may release, publish or disseminate freely. Content under Open Government Licence v3.0 (per site footer).
Useful for
- Use cases llm-inferred
- FRA baseline: identify whether a Welsh site lies within an internal drainage district and its managing boundaries · Drainage strategy constraints: map maintained watercourses, pumping stations and tidal flaps near a development · Planning context for low-lying Welsh land: screen drainage district exposure before site investigation
- Audience llm-inferred
- flood consultants · drainage engineers · hydrologists · planners · GIS analysts
Limitations
- Constraints llm-inferred
- Wales only · Update frequency unknown · Sluice locations provided only for Caldicot & Wentlooge Levels & Lower Wye and Powysland · Drainage district list stated as current as of 2022 · Only a WMS link is listed in the docs; download format not stated
Evidence
- https://datamap.gov.wales/layergroups/geonode:nrw_internal_drainage_district
- https://www.data.gov.uk/dataset/cce61c14-4fc6-47d1-a9cd-f7a49dfaa641/internal-drainage-districts-idd1
Check upstream coverage, uncertainty and licence before use. Station observations are not forecasts or design levels.