Transcript Fresh water on the Earth Surface - Foursix

The Earth’s
Fresh Water
Nathaniel Agustin A. Aluan
IV – 6 BEED
Hydrology- The branch of
Earth science that is
concerned with the
Earth’s water
About 97.5% of the Earth’s
water is found in the oceans.
Most of the oceans’ water
cannot be used by living things
because ocean water contains
salt.
Fresh water on the Earth
Surface
Fresh water makes about
2.5% of the Earth’s surface. Most
of the Fresh water cannot be
used because it is frozen in polar
Ice caps and other areas. In fact,
only 12% of the Earth’s fresh
water is available for use by
people and other animals.
http://blogs.princeton.edu/chm333/f2006/water/2006/12/why_dont_we_have_enough.html
The Hydrologic
Cycle
The Hydrologic cycle is
the movement of water from
the oceans and fresh water
sources to the air and land, and
then back to the oceans.
There are three main steps
in the Hydrologic cycle:
1. The first step involves
the heat energy of the sun.
This energy causes the
water on the surface of the
earth to change to vapor, or
gas. This process is called
evaporation.
2. The second step occurs
when the water vapor
changes back into a liquid.
This process is called
condensation.
3. During the third step, the
water is returned to the Earth
in the form of rain, snow, sleet
or hail. This process is
precipitation.
The remaining water that is
returned to the earth may run
off into ponds, lakes, streams,
rivers, or oceans. Some water
may soak into the ground and
become groundwater.
Most of the fresh water on
earths’ surface can be found
in:
1. Running water
2. Standing water
3. Frozen water
Running water
Rivers and streams are
very important sources of
fresh water. Many cities and
towns were built near the
rivers and streams.
River
http://www.escapeartist.com/Atuel_River_Estate/
Streams
http://www.hickerphoto.com/rain-forest-streams-9157-pictures.htm
The water was used for
irrigation, to generate electric
power, and for drinking.
Industry and commerce
depend on rivers for
transportation of supplies and
equipment. Rivers and streams
are also used for fishing,
boating and swimming.
Rain and melted snow that do not
evaporate or soak into the soil
flow into rivers and streams. The
water entering river or streams
after a heavy rain or during a
spring thaw of snow of ice is
called surface runoff.
The type of soil, rain or
snow falls on, greatly affects the
amount of runoff. Some soils
soak up more water than others.
These soils have more pore
space. Pore space is the
amount of space between the
particles of soil.
The number of plants growing
in the soil affects the amount
of runoff. The more the plants
the area, the more water is
absorbed by plant roots and
less runoff there is.
A land area which runoff
drains to a river or a system of
rivers and streams is called
watershed.
http://www.recycleworks.org/kids/watershed.html
Watershed prevents floods
and water shortages by
controlling the amount of water
that feeds into streams and
rivers. It also helps to provide a
steady flow of fresh water to
the oceans.
Standing water
Lakes and ponds are also
sources of fresh water. However,
lakes and ponds are standing
bodies of water. Like streams and
rivers, lakes and ponds receive
runoff from the land. The runoff
keeps them from drying up. These
standing bodies of water are
important sources of fresh water.
Lakes
http://free-extras.com/images/lake_landscape-12227.htm
Lakes are usually deep
depressions in the crust of the
earth that have filled with
fresh water. Rain, melting
snow, water from springs and
rivers and surface runoff fill
these depressions.
Ponds
Koi Fish Pond
Ponds are shallow
depressions in the earth’s crust
that have filled with fresh water.
They are usually smaller and
not as deep as lakes. Sunlight
can penetrate to the bottom of
a pond, whereas most lakes
have some deep areas that
sunlight cannot reach.
Reservoirs
http://www.larryhotz.com/new-reservoir/
Reservoirs are built by
damming a stream or river in a
low-lying area. When the
stream river is dammed, water
backs-up behind the dam.
Reservoirs have been built
near many cities and towns
and in mountainous regions
throughout the country.
Reservoirs have three purposes:
• help control water flow during
periods of heavy rain and run-off.
This prevents flooding.
• during periods of little rain and
runoff, reservoirs store water.
• Reservoirs can also be used in
generation of electrical power.
Frozen water
Glacier is a large mass of moving ice
and snow. Glaciers form in very cold
areas such as high in mountains and near
the poles. The snow that falls in these
areas does not completely melt because
of the very cold temperatures. As sow
falls, it buries the older snow. As the snow
builds up, the pressure on the older snow
squeezes the snow crystals together.
Eventually, ice forms. When the layers of
ice become very thick and heavy, the ice
begins to move.
Valley Glaciers
http://www.swisseduc.ch/glaciers/glossary/valley-glacier-en.html
Valley Glaciers
Small Glaciers that follow stream
channels down a mountain slope are
called Valley Glaciers. As valley
glaciers move downhill, they bend and
twist to fit the shape of the surrounding
land. The valley walls and the weight of
the ice itself keep glaciers from
breaking apart. Cracks on the surface
of the glaciers are called crevasses.
Continental Glaciers
http://www.homepage.montana.edu/~geol445/hyperglac/morphology1/
In the Polar Regions, snow
and ice have built up into very
thick sheets. These thick
sheets of ice are called
continental glaciers or polar
ice sheets.
Continental glaciers can
cover millions of square
kilometers of earth’s surface
and can be several thousand
meters thick. They slowly
move out from the center in
all directions.
Large continental glaciers
can be found in Greenland and
Antarctica. Nearly 80% of
Greenland is covered by ice.
More than 90% of Antarctica is
covered by ice. These
continental glaciers could be
another source of fresh water.
Icebergs
http://free-extras.com/images/iceberg-12478.htm
At the edge of the sea,
continental glaciers form
overhanging cliffs. Large
chunks of ice often break off
from glaciers and drift into the
sea. These large chunks of ice
are called icebergs.
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