River Severn

The River Severn (Welsh: Afon Hafren, pronounced [ˈavɔn ˈhavrɛn]), at 220 miles (354 km) long, is the longest river in Great Britain.[4][5] It is also the river with the most voluminous flow of water by far in all of England and Wales, with an average flow rate of 107 m3/s (3,800 cu ft/s) at Apperley, Gloucestershire. It rises in the Cambrian Mountains in mid Wales, at an altitude of 2,001 feet (610 m), on the Plynlimon massif, which lies close to the Ceredigion/Powys border near Llanidloes. The river then flows through Shropshire, Worcestershire and Gloucestershire. The county towns of Shrewsbury, Gloucester and the City of Worcester lie on its course.

River Severn
The river seen from Shrewsbury Castle
Tributaries (light blue) and major settlements on and near the Severn (bold blue)
Location
CountryEngland and Wales
RegionMid Wales, West Midlands, South West
CountiesPowys, Shropshire, Worcestershire, Gloucestershire
CitiesShrewsbury, Worcester, Gloucester, Bristol
Physical characteristics
Source 
  locationPlynlimon, Powys, Wales
  coordinates52.493464°N 3.734597°W / 52.493464; -3.734597
  elevation610 m (2,000 ft)
MouthSevern Estuary
  location
Bristol Channel, United Kingdom
  elevation
0 m (0 ft)
Length354 km (220 mi)
Basin size11,420 km2 (4,410 sq mi)
Discharge 
  locationBewdley, Worcs. SO 7815 7622[1]
  average61.17 m3/s (2,160 cu ft/s)[1]
  maximum533.48 m3/s (18,840 cu ft/s)max recorded on 1947-03-21[2]
Discharge 
  locationApperley, Glos.
  average107 m3/s (3,800 cu ft/s)
Discharge 
  locationMontford, Shrops.[3]
  average43.46 m3/s (1,535 cu ft/s)
Basin features
Tributaries 
  leftVyrnwy, Tern, Stour, Warwickshire Avon, Bristol Avon
  rightTeme, Leadon, Wye

The Severn's major tributaries are the Vyrnwy, the Tern, the Teme, the Warwickshire Avon, and the Worcestershire Stour.

By convention, the River Severn is usually considered to end, and the Severn Estuary to begin, after the Second Severn Crossing, between Severn Beach in South Gloucestershire and Sudbrook, Monmouthshire. The total area of the Estuary's drainage basin is 4,409 square miles (11,419 km2). That figure excludes the area of the River Wye and the Bristol Avon, both of which flow into the Severn Estuary. The Estuary discharges into the Bristol Channel, which opens into the Celtic Sea and from there into the Atlantic Ocean.