River Severn

The River Severn (Welsh: Afon Hafren, Latin: Sabrina) is the longest river in the United Kingdom, at about 354 kilometres (220 mi), and the second longest in the British Isles, behind the River Shannon. It rises at an altitude of 610 metres (2,001 ft) on Plynlimon, Ceredigion near Llanidloes, Powys, in the Cambrian Mountains of mid Wales. It then flows through Shropshire, Worcestershire and Gloucestershire, with the county towns of Shrewsbury, Worcester, and Gloucester on its banks. With an average discharge of 107 m³/s at Apperley, Gloucestershire, the Severn is the greatest river in terms of water flow in England and Wales.

The river is usually considered to become the Severn Estuary after the Second Severn Crossing between Severn Beach, South Gloucestershire and Sudbrook, Monmouthshire. The river then discharges into the Bristol Channel which in turn discharges into the Celtic Sea and the wider Atlantic Ocean. The Severn's drainage basin area is 11,420 square kilometres (4,409 sq mi), excluding the River Wye and Bristol Avon which flow into the Severn Estuary. The major tributaries to the Severn are the Vyrnwy, Teme, Warwickshire Avon and Stour.