The Severn Bridges crossing near the mouth of the River Severn
The River Thames in London
The River Tay in Perth, by measured flow the largest in Great Britain

This is a list of the longest rivers of the United Kingdom.

Longest rivers of the United Kingdom

RankRiverLength (miles)Length (km)Mean Flow (m3/s)[1]MouthCountry
1River Severn[2]220354107.4Severn EstuaryWales/England
2River Thames[2]21534665.4Thames EstuaryEngland
3River Trent[2]18529789.0The HumberEngland
4River Wye[3]15525073.1Severn EstuaryWales/England
5River Great Ouse[2]14323015.6The WashEngland
6River Ure/River Ouse, Yorkshire12920869.8The HumberEngland
7River Tay[2]117188179.0Firth of TayScotland
8River Clyde10917648.5Firth of ClydeScotland
9River Spey10717265.7Moray FirthScotland
10River Nene[2]1001619.3The WashEngland
11River Bann / Lough Neagh9915992.2Atlantic OceanNorthern Ireland
12River Tweed[2]9615581.7North SeaScotland/England
13River Avon, Warwickshire9615417.3River Severn*England
14River Eden, Cumbria9014553.7Solway FirthEngland
15River Dee, Aberdeenshire8714047.8North SeaScotland
16River Witham821325.2The WashEngland
17River Teme8113018.2River Severn*Wales/England
18=River Don, Aberdeenshire[2]8012921.3North SeaScotland
18=River Foyle8012958.8Atlantic OceanNorthern Ireland/Republic of Ireland
20River Usk[4]7812528.6Severn EstuaryWales
21River Teifi[5]7612229.5Cardigan BayWales
22=River Tywi7512139.9Carmarthen BayWales
22=River Ribble7512034.0Irish SeaEngland
22=River Avon, Bristol7512022.2Mouth of the SevernEngland
25=River Tyne[2]7311845.2North SeaEngland
25=River Swale7311820.2River UreEngland
27River Derwent, Yorkshire7211517.4River Ouse, YorkshireEngland
28=River Aire7111436.5River Ouse, YorkshireEngland
28=River Nith7111436.5Solway FirthScotland
30=River Tees7011322.2North SeaEngland
30=River Medway7011311.7Thames EstuaryEngland
30=River Mersey7011337.1Irish SeaEngland
33=River Dee, Wales[2]7011234.1Dee EstuaryWales/England
33=River Don, South Yorkshire7011216.3River Ouse, YorkshireEngland

There seems to be little consensus in published sources as to the lengths of rivers, nor much agreement as to what constitutes a river. Thus the River Ure and River Ouse can be counted as one river system or as two rivers. If it is counted as one, the River Aire/ River Ouse/Humber system would come fourth in the list, with a combined length of 161 miles (259 km); and the River Trent/Humber system would top the list with their combined length of 222 miles (357 km).[6] Also, the Thames tributary, the River Churn, sourced at Seven Springs, adds 14 miles (23 km) to the length of the Thames (from its traditional source at Thames Head). The Churn/Thames' length at 229 miles (369 km) is therefore greater than the Severn's length of 220 miles (354 km). Thus, the combined Churn/Thames river would top the list. Sue Owen et al., in their book on rivers, generally restrict the length to the parts that bear the same name. Thus the River Nene is quoted at 100 miles (160 km), but would be around 5 miles (8 km) more if the variously named sources were included. Many of the above lengths are considerably different from Sue Owen's list, some longer and some shorter.[2]

Where a river ends in an estuary the conventional British approach has been to treat the river as ending at the end of the administrative zone. Thus the Severn ends at the mouth of the Bristol Avon and the Thames at the Yantlet Line. The currently accepted end of the Severn Estuary is about 18.5 miles (29.8 km) further, and the Port of London's authority stretches now to Margate, 30 miles (48 km) further. Other countries have different conventions, making comparisons of limited value. Those rivers which empty into other (non-tidal sections of) rivers are indicated in the table thus*. In Yorkshire, the Aire, Derwent and Don all empty into a tidal section of the Yorkshire Ouse.

The figures for mean flow are derived from those offered up by the National River Flow Archive, in particular the flow measured at the lowermost gauging stations on each named watercourse. Sometimes the figures of further downstream tributaries are combined with those of the main stem river to provide a more realistic flow figure for the lowermost non-tidal stretch of a watercourse. Some major UK rivers (in terms of flow) are omitted from the list above simply because they are also short.

See also

References

  1. ↑ "Search Data". National River Flow Archive.
  2. 1 2 3 4 5 6 7 8 9 10 11 Owen, Susan; et al. (2005). Rivers and the British Landscape. Carnegie. ISBN 978-1-85936-120-7.
  3. ↑ "SSSI Citation River Wye (upper Wye)" (PDF). Natural Resources Wales. Retrieved 14 November 2020.
  4. ↑ "Usk management catchment Summary" (PDF). Natural Resources Wales. Retrieved 14 November 2020.
  5. ↑ - River Teifi - CCW Archived 2014-02-21 at the Wayback Machine
  6. ↑ http://copranet.projects.eucc-d.de/files/000165_EUROSION_Humber_Estuary.pdf
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