What is the longest river in the UK?
The longest river in the United Kingdom forms the boundary between Wales and England in part of its course.
The longest river in the United Kingdom is the River Severn, 354 km long and with an average discharge of 61.17 m3/s.
The River Severn rises in the Plynlimon mountain, located in Ceredigion county (Wales), at about 610 meters above sea level.
The Severn flows into the southwest of England, into the Bristol Channel, which in turn discharges its waters into the Celtic Sea and finally into the Atlantic Ocean. The river forms a large estuary, which has one of the highest tides in the world and creates a border between Wales and England.
The surface area of the basin is 11,420 km2. Major tributaries of the Severn River on both banks include:
- Right bank of the Severn: river Teme (130 km), river Wye (215 km) and river Usk (112 km).
- Left bank of the Severn: River Vyrnwy (64 km), River Tern (48 km) and River Avon (135 km).
Severn river basin