Transcript Water on the Surface

Surface Water
Text Book page # 318 – 325
What is a
river
system?
A river system
includes a river in
addition to any
streams or
tributaries that
flow into that
river.
Tributary
A stream or
smaller river
that feeds
into a main
river.
Tributaries
• Flow downward
toward the
main river.
• What force
causes this?
• Pulled down by
the force of
Gravity!
Watershed
The land
area that
supplies
water to a
river
system.
Amazon
River
Basin
Largest
watershed
in the
world.
Divide
A ridge of
land that
separates
one
watershed
from
another.
The
Continental
Divide, the
longest divide
in North
America,
follows the line
of Rocky
Mountains
Lakes and Ponds
• Bodies of fresh
water
• Contain still or
standing water
• Lakes and
ponds form
when water
collects in
hollows and lowlying areas of
land.
Ponds are thriving
habitats for various
plants and animals.
Algae serves as food
for many animals.
Ponds are typically
very shallow and
sunlight can reach
plants on the bottom.
Ponds
Lakes are bigger
and deeper than
ponds.
Sunlight does not
reach the bottom
in a deep lake.
Lake bottoms
consist of sand,
pebbles and rock.
Lakes
Lakes
Lakes can form from:
1. Cut-off meandering rivers (Oxbow lakes)
2. Erosion by ice (eg. The Great Lakes)
3. Extinct volcano craters (eg. Crater Lake,
Mount Mazama – Oregon, USA)
4. Movements of Earth’s crust (eg. Lake
Tanganyika and Lake Victoria in Central
Africa)
5. Manmade lakes are formed by river
dams.
Oxbow Lake
Crater Lake, Mount Mazama –
Oregon, USA
• Crater Lake, Mount Mazama – Oregon,
USA
Lake
Tanganyik
a and Lake
Victoria in
Central
Africa
Lakes- Human Uses
•
•
•
•
Drinking water
Irrigation
Boating
Fishing
Reservoir- A lake that stores water for
human use.
Lake Turnover
When the water in a lake mixes due to
temperature change causing minerals, plant
matter, and other nutrients to rise to the
surface.
This refreshes the nutrients of the lake.
Eutrophication
When nutrients build up in a lake over many
years.
Algae forms a thick green scum on the surface of
the water.
Icebergs
Large chunks of
ice that break off
of a glacier and
float away into
the ocean.
Made of frozen
FRESHWATER.
Wetland
A land area
that is
covered with
a shallow
layer of
water during
some or all
of the year.
Three types of freshwater
wetlands
1. Marshes
• Are usually grassy
areas covered by a
shallow water or a
stream.
• Team with cattails
and other tall,
grasslike plants.
Three types of freshwater wetlands
2. Swamps
• Look more like
flooded forests, with
trees and shrubs
sprouting from the
water.
• Located in warm,
humid climates,
where trees grows
quickly.
Three types of freshwater wetlands
3. Bogs
• More common in cool,
Northern areas.
• Often form in
depression left by
melting ice sheets
thousands of years
ago.
• The water in bogs
tends to be acidic, and
mosses thrive in these
conditions.
The
Everglades
–
Example of a
Wetland
Importance of Wetlands
• Because of their sheltered waters and rich
supply of nutrients, wetlands provide habitats for
many living things.
• They act as natural water
filters (eg. Pickerel weed filter
pollutants from water).
• Help control floods by absorbing extra runoff
from heavy rains.