A watershed is the area separating two different drainage basins/river systems.
The Continental Divide of the Americas is an example of a mountain ridge that separates river systems. Further examples include Northern Divide or Laurentian Divide.
A divide
A mountain ridge that separates river systems is called a watershed or a drainage divide. This geographic feature determines the direction in which water flows, dividing the flow of water into different river basins.
continmental dividecontinental divide
That would be the Columbia River. This river separates approximately two thirds of southern Washington from northern Oregon. At a place on the 46th parallel north this river total enters the state of Washington, and this parallel becomes the border line that separates the two states.
there are no river in paraguay!
The eural river separates Europe from Asia
Ural River. It is the traditional boundary that separates Europe and Asia.
There is no single river that separates all the states of Australia.However, the Murray River separates the two states of Victoria and New South Wales, forming the border for much of the way before continuing into South Australia.
The Chattahoochee River separates the Eastern and Central time zones. On the eastern bank of the river, it's Eastern time, while on the western bank, it's Central time.
the two major river systems are the Amazon and the Parana.