This is its catchment - surrounded by its watersheds.
an area drained by a river is called pooo lol
River Basin
Basin
a watershed, also called a drainage basin, is an area drained by a river.
An area drained by a river or river system is called a drainage basin.
A Basin
A river system that operates inside a drainage basin. A drainage basin is the area of land drained by a river and its tributaries.
The area of land drained by a river is called a "catchment area". It is so-called because is the the area that catches the precipitation (rainfall).Another term is "river basin", but this is less specific.(The geographical term, "catchment area", is often used to describe the area served by, say, a school or hospital).
basin
an area drained by the river .
river basin
river or lakes duhhh