A watershed is an area of land that divides two different river systems where water is drained by two different rivers. It is an important dividing point between the two. The term can also be used to describe any dividing point or a point that marks a change. A watershed can also be called a water parting or a divide.
Safeopedia Explains Watershed
The defining characteristics of a watershed are that it is a high area of land, which forces water to drain from it to lower areas like rivers. It is specifically used when discussing rivers or water drainage from the earth and waters that supply our drinking water or fresh water. Watersheds are important for the health of these water sources and are affected by various forms of pollution, such as runoff and erosion.