UK Hydrological Units for River Flow Measurement and Catchment Analysis

Integrated Hydrological Units define geographical reference units for hydrological purposes across the United Kingdom. The web map service contains five hierarchical polygon layers representing Hydrometric Areas, Groups, Sections, and Catchments, with naming conventions based on major river flows. Government Digital Service provides this data, which covers Great Britain and Northern Ireland at the coarsest level, but excludes Northern Ireland from detailed layers due to a lack of suitable river geometry data.

Use Cases

• Modeling river flow and water resource distribution based on hierarchical catchment boundaries.
• Mapping hydrometric data collection points to standardized geographical units.
• Analyzing drainage areas between confluences of named watercourses using Section polygons.
• Creating regional water management plans using the non-overlapping Hydrometric Area layers.

Strengths

• Provides five distinct, hierarchical spatial layers for analysis at different scales.
• Polygons within each layer are designed without gaps, ensuring complete spatial coverage.
• Includes two versions of the coarsest Hydrometric Areas layer to meet differing user needs.

Limitations

• Detailed layers (Groups, Sections, Catchments) cover only Great Britain, not Northern Ireland.
• Row count and specific data formats beyond WMS are unknown, limiting suitability assessment.
• Column-level documentation is absent; field semantics must be inferred after access.

Provenance

Source

Government Digital Service

Geography

United Kingdom (Great Britain fully, Northern Ireland partially)