Page 116 - SST Class 08

their tributaries. Which originate from the
cooking, drinking, washing
we use water in industries,
agriculture, transport,
generation of electricity
etc. Most of the water on
the earth is found in oceans Waterfall
and seas, which is saline and not fit for domestic,
agricultural and industrial purposes. Freshwater is
available on the earth surface in the form of rivers,
streams and wetlands such as swamps or marshes.
Rainfall is also an important source of freshwater.
Distribution of Water
The distribution of water on the earth is highly
uneven. 97% of the total volume of water on the
earth is found in oceans and seas, 2% is found in
the form of freshwater. This water is suitable for
human consumption.
The distribution of freshwater resources is highly
uneven on the surface of the earth. It is varied not
only from season to season but also from region to
region. It is hard to believe that only 2% of the
total volume accounts for freshwater, out of which
87% is frozen as ice sheets and glaciers, 12% is
groundwater and 1% is in the river and lake that is
available for human use. Given diagram shows
the freshwater distribution of the world.
Salt Water 98%
Freshwater
2%
Ice 87%
Groundwater Rivers and
12% Lakes 1%
Freshwater distribution
Distribution of Water in India
India has vast water resources; however, the
distribution of water is very uneven. The rivers
and monsoon are the two main sources of water
in our country. Rivers help to carry water to those
places where rainfall is insufficient, so that
irrigation can be carried out in those places.
There are many perennial rivers in the north such
as the Ganga, Yamuna, Brahmaputra, Indus and
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Himalayas. These rivers have made the Northern
Plains fertile. There are a number of rivers in the
southern peninsular region also, though some of
them are seasonal in nature, such as the Narmada,
Mahanadi, Tapi, Krishna, Kaveri etc.
Besides rivers, India gets sufficient rainfall during
the monsoon, though for a limited period of about
four months in a year. However, the rainfall is
uneven and it results in floods and droughts in
different regions.
As the rivers and monsoon cannot supply water
for irrigation and other purposes all over India,
other means are used, such as canals, tanks, wells
and tubewells.
Canals are dug from rivers. Canals can be
inundation canals or perennial canals. Inundation
canals get filled up when the source river is
flooded; while perennial canals carry water round
the year because they have been dug from the
perennial rivers. As plains are very suitable for
canals, there is a large network of canals in India
such as, Bhakra Canal, the Sirhind Canal, in
Punjab and Haryana; the Eastern Yamuna Canal,
the Sharda Canal in Uttar Pradesh and the Indira
Gandhi Canal in Rajasthan. In addition to these,
there are canals in Coastal Plains also.
Digging of canals is not feasible in South India
due to rocky land surface. So, tanks are dug to
store rainwater which is used during the dry
season. Wells and tubewells are used to tap
groundwater. India has 4,300 dams in operation.
The Problem of Water Scarcity
Water shortage has become a major problem for
the world today. In 1999, only 40 countries were
facing water scarcity but it is estimated that by
2025 around 65 countries would face this
problem. Korea, India, Nigeria, Peru and Poland
are also likely to suffer from water scarcity.
The countries which are facing the problem of
water scarcity are mostly developing or under
developed. Most of these countries are poverty
stricken. They experience regular droughts and
other water problems but cannot afford to import
water because of poor economic backup. In some