The River Cherwell (/ˈtʃɑrwɛl/ CHAR-well, particularly near Oxford, or /ˈtʃɜrwɛl/ CHUR-well, particularly in north Oxfordshire) is a major tributary of the River Thames in central England. It rises near Hellidon in Northamptonshire and flows south through Oxfordshire for 40 miles (64 km)to meet the Thames at Oxford. It adds a significant discharge to the Thames—when entering Oxford, the Thames's discharge is 17.6 m³/s (622 cu ft/s), but after leaving and consuming the Cherwell it has increased to 24.8 m³/s (876 cu ft/s).