The Hydrological Areas are a polygon dataset showing 139 hydrological units across England and parts of Wales, that have been defined by the Environment Agency. The units show areas that have broadly similar hydrological characteristics. Many of the hydrological areas are defined by surface water (river) catchments, which are areas 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. Other units are defined based on hydrogeological characteristics, where this is more appropriate, such as groundwater recharge areas. Attribution statement: © Environment Agency copyright and/or database right 2015. All rights reserved. © SEPA. Some features of this information are based on digital spatial data licensed from the Centre for Ecology and Hydrology © NERC (CEH). Contains OS data © Crown copyright [and database right]. Derived in part from 1:50,000 scale BGS Digital Data under Licence 2011/051/F. British Geological Survey © UKRI 2021
