Ordnance Survey (OS) make an open dataset of rivers available as OS Open Rivers vector polylines under an Open Government Licence, derived from the detailed OS MasterMap Water Layer. Although widely used by the practitioner and the academic community it is not fully topologically connected, limiting its suitability for several uses and research applications such as linear referencing and reach analysis, hydro-ecological analysis, water quality monitoring, restoration and remediation prioritisation, connectivity planning and integration in decision support tools. The entire river network for Great Britain was corrected for topological errors and attributed with additional data. The network consisted of 183,349 polylines representing 147,387 kilometres.

To ensure the network was a topologically correct river network, canals and channels that broke the dendritic connectivity of the river network were removed. The network was further simplified by removing loops. Small unconnected sections that were within the great catchment they sat within were also deleted out.

With the topological errors removed, the network was passed through the river network processing tool RivEX to create added-value attribution. Encoding the network with these pre-computed values allows for rapidly analyse of the network alongside site data (points snapped to the network).

Further details on edits made to the network and the attribute fields added are recorded in the lineage and fields section of the metadata.