The name "Adur" was attributed to the current river because of a mistaken location for the Roman "Portus Adurni" by the 17th century poet Michael Drayton in his book 'Polyolbion'.
The River Adur rises four miles south of Horsham and runs south-east skirting Coolham, Shipley and West Grinstead before meeting the eastern tributary midway between Ashurst to the west and Henfield to the east. The eastern tributary rises in two tributaries south of Haywards Heath, and south of Burgess Hill that meet at Twineham. The River Adur reaches the sea at Shoreham-by-Sea where the mouth has been deflected two miles to the east by the longshore drift.
Going upstream with the incoming tide through the centre of New Shoreham, the flood tide will flow under seven bridges before it reaches the village of Bramber after 6.4 km (4 miles). The river then passes about one mile east of the town of Steyning.

