ESS124
Prof.
Jin-Yi Yu
Watersheds
The geographic area that drains into a river or stream is
called a watershed.
The
Mississippi River watershed covers much of the central United States.
The height of the water surface of a river is called its
stage.
A rivers stage naturally fluctuates as rain falls and drainage
occurs within a watershed.
When a river raises to a level where it begins to flood, the
river is said to be at flood stage.
Hydrologists often use flood stage as a reference level to
express the intensity of
a flood.