Definition

The land area that drains into a particular watercourse or body of water. Sometimes used to describe the dividing line of high ground between two catchment basins.

Millennium Ecosystem Assessment 2005 ¹

Summit or boundary line separating adjacent drainage basins.

International Glossary of Hydrology, WMO/UNESCO, 2012 ²

Note: the US use of the term generally refers to the area of land drained (which equates to ‘river/drainage basin’). The European use of the term ‘watershed’ refers to the boundary line (in the US this boundary line is known as the ‘water divide’).

Adapted from International Glossary of Hydrology, WMO/UNESCO, 2012 ²