what is a watershed

A watershed is an area of land where all the water that falls within it drains or "sheds" into a specific waterbody, such as a river, lake, or ocean. The term "watershed" is often used interchangeably with "drainage basin" or "catchment area". Watersheds can be small, such as a modest inland lake or a single county, or they can be large, encompassing multiple states or even countries. The size of a watershed is defined on several scales, based on the geography that is most relevant to its specific area. Watersheds are important because they are a logical unit of focus for studying the movement of water within the hydrological cycle, and because they are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins.