Surface Water:
River Systems:
Notice the changes that occur as a river flows from its origin
to the ocean.
Tributaries
 The streams and smaller rivers that feed into
a main river are called tributaries.
 Tributaries flow downward toward the main
river, pulled by the force of gravity.
 A river and all its tributaries together
make up a river system.
Watersheds
 Just as all the water in a bathtub flows toward
the drain, all the water in a river system
drains into a main river.
 The land area that supplies water to a river
system is called a watershed (river basin).
 *We live in the Yadkin-Peedee river basin!
This map shows watersheds of several large rivers in the
continental United States. Each river’s watershed consists of
the region drained by the river and all its tributaries.
Divides
 One watershed/river basin is separated from
another by a ridge of land called a divide.
 Streams on each side of the divide flow in
different directions.
 The Appalachian Mountains in NC are the
eastern continental divide.
The Nile River in Africa flows from south to north.
What can you infer about the slope of the land
through which the Nile River flows?
Ponds and Lakes
 Ponds and lakes are bodies of fresh water.
 Unlike the moving water in streams and
rivers, ponds and lakes contain still, or
standing water
 Pond vs. Lake:
o Ponds are smaller and shallower than
lakes.
o Sunlight usually reaches to the bottom
of all parts of a pond. Most lakes have
areas where the water is too deep for
sunlight to reach the bottom.
 Ponds and lakes form when water collects
in hollows and low-lying areas of land.
o The water comes from precipitation,
runoff from higher areas, and/or are fed
by a river.
Lake Formation:
 Lakes and ponds form when water collects in
hollows and low-lying areas of land.
 A river channel, for example, can form a lake
as it changes over time
- It bends and loops as it encounters
obstacles in its path.
- Eventually, a new channel might form,
cutting off a loop. The cut-off loop may
become an oxbow lake.
∙ Some other natural lakes, such as the Great
Lakes, formed in depressions created by ice
sheets that melted at the end of the Ice Age.
∙ People can also create a lake by building a dam
across a river. The lake may be used for
supplying drinking water, for irrigating fields, and
for recreation. A lake that stores water for human
use is called a reservoir.
How Lakes can Change
 Nutrients are substances such as nitrogen
and phosphorus that enable plants and algae
to grow.
Long Term Changes:
 Over many years, the nutrients build up in the
lake in a process called eutrophication .
 As eutrophication causes more algae to grow,
a thick, green scum forms on the surface of
the water, also called an algal bloom.
Wetlands:
 A wetland is a land area that is covered
with water some or all of the year.
 There are 3 types of wetlands: marshes,
swamps, and bogs
- Marshes = grassy covered by shallow
water (estuary)
- Swamps = look like flooded forests
with trees in the water
- Bogs = acidic water, lots of mosses
Importance of Wetlands:
 Wetlands provide sheltered waters and a
rich supply of nutrients for many living
things.
 They also can help control floods by
absorbing extra runoff from heavy rains.
Threats:
 The wetlands are threatened by
agriculture and development.
 The Everglades in Florida are shrinking
due to land development.
Surface Water Review Questions:
1. What bodies of water make up a river
system?
River and tributaries.
2. How is a watershed related to a river
system?
A watershed is the land area that supplies
water to a river system, where all the
water drains.
3. How are lakes different from ponds?
Lakes are larger and deeper than ponds.
Sunlight reaches the bottom of a pond; in
a lake, sunlight cannot penetrate the
bottom.
4. List two ways lakes and ponds form.
Water collecting in hollows and/ or lowlying areas of land, depressions created
by ice sheets, building of a dam.
5. What is the main difference between a
reservoir and most other lakes?
A reservoir is man-made. Other types of
lakes form naturally.
6. What are the 3 types of Wetlands?
Marshes, swamps, and bogs