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Chapter 4 WAtEr

The earth appears blue from the outer space because of its immense water bodies. Water
covers about 71% of the earth’s surface.

We need water for almost all the activities like—drinking, cooking, washing clothes or
utensils and many more. We also need water to generate electricity and for transportation
too. Water is a major source of our livelihood.
The following table shows the distribution of water on the earth surface.

S.No. Water bodies Volume of water (in %) Nature of Water

1. Oceans 97.3 Saline Water
2. Ice Caps 02.0 Fresh Water
3. Ground water 0.68 Fresh Water
4. Fresh lakes and inland seas 0.009 Fresh Water

5. Salt lakes 0.009 Saline Water
6. Atmosphere 0.0019 Fresh Water
7. Rivers 0.0001 Fresh Water

tWo sourCEs of WatEr

1. surfacE WatEr
It is the water that is present on the surface
of earth. Sources of surface water are rivers,
lakes, ponds, streams, reservoirs, even the
oceans.
grouNd WatEr Surface water Sources Groundwater Sources
Almost 30 percent of the world’s fresh water reserves are found under the ground. When
it rains, some of the water soaks into the soil passing between soil, gravel and rock and
gets deposited below the earth’s surface. This water is called Ground water. This can
take days, years, decades or millennium. Water sheds, aquifers, wells and springs are the
examples of underground water.
distriButioN of WatEr BodiEs

Water is found in solid, liquid and gaseous form. About 2/3rd of the earth is covered with
water yet the water which is suitable for human consumption is only 3%. 97% is saline water
and is found in oceans and seas. This water is not suitable for human consumption. Out
of the 3% of fresh water, 2% is in the form of ice caps and glaciers and only 1% is available
in the form of surface water. This is found in rivers, lakes, ground water or in the gaseous
form as water vapour in the atmosphere.

Fresh water is the most valuable natural resource and must be used judiciously.

22 Social Studies-7