Although a mere 0.03% of all freshwater in the world is found in river systems, running water is
probably the most important geomorphic agent in shaping the face of the Earth.
What are the five processes of the hydrologic cycle? What are the primary pathways of
Together, these five processes -
condensation, precipitation, infiltration, runoff, and
- make up the Hydrologic Cycle. Water vapor condenses to form clouds, which
result in precipitation when the conditions are suitable. Precipitation falls to the surface and infiltrates
the soil [as
, where it can recharge groundwater] or flows to the ocean as runoff.
Surface water (e.g., lakes, streams, oceans, etc.), evaporates, returning moisture to the atmosphere,
while plants return water to the atmosphere by transpiration."
Where does water in streams come from?
– water that seeps up from the groundwater into the stream.
– water running off of the nearby land surface and flowing into the stream.
Runoff occurs when the soil becomes saturated and water can no longer infiltrate the
soil, so it runs off/over the land's surface.
static water bodies
– water is fed to a stream from an
of a lake and pond (e.g.,
the Mississippi River begins at Lake Itasca in Minnesota).
What is a drainage basin? A drainage divide? What is the continental divide?
The area that contributes runoff to a particular stream is known as its
Drainage basins are separated from one another by drainage divides.
drainage divide, the boundary of a drainage basin."
, which runs from Alaska to New Mexico (basically along the
Rockies), separates the water which drains to the Pacific Ocean from the water which
drains to the Atlantic Ocean or Gulf of Mexico.
What is a tributary? A confluence?
Each small stream that contributes water to a larger fluvial (river) channel is called a
The place where two tributaries or streams meet is a
It is important to understand how streams operate because of their influence on our lives. Streams
supply us with water for drinking and irrigation, a transportation system, energy for electricity, a
waste disposal system, etc. They can also have a devastating effect on all these systems as well as
residential areas during flooding.
What are fluvial processes? Describe how fluvial processes shape the earth’s surface.