Region Of Influence Gauges

The Region of influence Gauging Stations (ROI) are held separately from the Local Data Gauge datasets. The ROI set are a static set that cannot be updated by the user. The following mandatory data are held for the ROI stations:

• 30 Hydrology Of Soil Types (HOST) class fractional extents within the catchment.
• Value of 1961-1990 average annual runoff (mm/year).
• Sets of 101 point annual and 12 monthly flow duration plotting positions [Q(x)%MF, P(x)] where P(x) is the exceedance probability which takes values of [0.1, 1, 2, …., 98, 99, 99.9] and Q(x)%MF is the flow expressed as a percentage of the mean flow.
• Mean Monthly Runoff Volumes (MMRV) which are the average volume of runoff in a month expressed as a percentage of the average total runoff within the year (dimensionless).

Local Data Gauges

The Local Data Gauges (LDG) are Gauging Stations that have been selected as suitable for local data (see Gauges - Local Data). To be selected the gauge requires a naturalised FDC (or set of naturalised FDC if your Organisation has selected multiple period of records). The naturalised FDC will be automatically updated when artificial influences are updated within the gauged catchment.

Core Spatial Datasets

• UK Centre for Ecology and Hydrology (UKCEH) Integrated Hydrology Digital Terrain Model (IHDTM)
• 30 1km resolution Hydrology of Soil Types (HOST) grids (dimensionless)
• 1km average annual runoff grid (mm/year) for the full period of record (plus additional period of records if your Organisation has selected multiple)
• Lake outlets with attributes of the surface area of the lake and the catchment area draining to the lake (currently only available in Scotland)

Ancillary Spatial Datasets

The following are provided for regulatory organisations that hold the required data licenses:

• Standard Average Annual Rainfall SAAR61-90 (mm/year)
• Potential Evaporation PE61-90 (mm/year)