The 'WFD River Waterbody Catchments' are a polygon Shapefile dataset collated as defined for the implementation of the Water Framework Directive. Catchments are defined as an area of land from which all surface run-off flows through a series of streams, rivers and, possibly, lakes to a particular point in the water course such as a river confluence. Delineation of the river catchment boundaries primarily utilised the CEH Flow Grid hydrological model run with CEH Integrated Hydrological Digital Terrain Model (IHDTM) data so as to determine water drainage into river stretches. Upstream catchment size was calculated within an ESRI GIS environment using the extension Arc Hydro.
