Synonyms: Basin, Drainage Area, Drainage Basin, Catchment, Catchment Basin, River Basin, Water Basin
A watershed is area of land where surface water and runoff converges to one specified point. The end point is usually another river, lake, stream, bay, or ocean. The boundaries of a watershed are determined by the topography and slope of the land. Many small watersheds (known as sub-watersheds) make up larger watersheds.
Example of sub-watersheds: The Chesapeake Bay watershed consists of the Susquehanna, Potomac, Rappahannock, York, James, and other rivers. Each of those rivers have their own designated watershed areas. And all of the creeks and streams that contribute to those 5 main rivers also have their own designated watershed areas. The total of the sub-watersheds all makeup the Chesapeake Bay watershed.