Water Resources
Class 10 -Notes (Social Science)
Geography - Chapter 3
Water and its facts: Three-fourth of the earth’s
surface is covered with water but only a small proportion of it accounts for
freshwater that can be put to use. Water is a renewable resource.
Fresh water: 96.5 per
cent of the total volume of world’s water is estimated to exist as oceans and
only 2.5 per cent exists as fresh water. 70 per cent of the fresh water occurs
as ice sheets and glaciers in Antarctica, Greenland and the mountainous regions
of the world. Less than 30 per cent is stored as groundwater in the world’s
acquirers. Fresh water is mainly obtained from surface run off and ground
water. This is continually being renewed and recharged through the hydrological
cycle. All the water moves within the hydrological cycle making water a
renewable resource.
Three fresh water sources
are: Precipitation—from rainfall; Surface water—in rivers, lakes, etc.; Ground
water—water stored in underground acquirers which gets recharged by rainfall.
Water Scarcity and the Need for Water Conservation and Management-
The availability of water resources
varies over space and time.
1.Water scarcity is caused by over-exploitation, excessive use and unequal
access to water among different social groups.
2. Water resources are being over-exploited to expand irrigated areas for
dry-season agriculture.
3. In some areas, water is sufficiently available to meet the needs of the
people. But, those areas still suffer from water scarcity due to bad quality of
water.
The need of the hour is to conserve and manage our water resources:
1.To safeguard ourselves from health hazards.
2.To ensure food security, continuation of our livelihoods and productive
activities.
3.To prevent degradation of our natural ecosystems.
Water scarcity: Water scarcity means shortage of water. It is usually
associated with regions having low rainfall or drought prone areas.
There are many other
reasons which lead to scarcity of water:
- Large growing
population;
-In the agricultural
sector,
-water resources are
being over-exploited to expand irrigated areas and dry- season agriculture;
-More water required for
irrigation purposes to facilitate higher food production, i. e., for doing
multiple cropping and for HYV seeds;
- There is greater demand
for water with growing urbanization and industrialization; An unequal access to
water among different social groups;
-The quality of water is
deteriorating, i.e., getting polluted by domestic and industrial wastes,
chemical fertilizers and pesticides used in agriculture;
-Excessive use of water
by industries which also require water to generate hydro-electric power to run
them; and Over exploitation of water in the urban areas.
-Adverse effects of
over-exploitation of ground water resources:
-Pumping out more water
from under the ground may lead to falling ground water levels. It will
adversely affect water availability.
This, in turn, will
affect our agriculture and food security of the people. Impoverishment of water
resources may adversely affect the ecological cycle.
Main causes of water
pollution: Domestic wastes,
especially urban sewers; industrial wastes are disposed off in the water
without proper treatment; chemical effluents from industries and from
agricultural sector; and many human activities, e.g., religious rituals and
immersing of idols, etc. in the water also pollute water.
Measures for water conservation: Do not overdraw the ground water, recharge it by techniques
like rainwater harvesting; tapping rainwater in reservoirs, watershed
development programmes, etc. Avoid wastage of water at all levels and do not
pollute the water. Adopting water conserving techniques of irrigation, e.g.,
drip irrigation and sprinklers etc., especially in dry areas.
Multi-Purpose River Projects and Integrated Water Resources Management :
In ancient times, we used to conserve water by constructing sophisticated
hydraulic structures like dams built of stone rubble, reservoirs or lakes,
embankments and canals for irrigation. We have continued this tradition in
modern India by building dams in most of our river basins.
DAM- A dam is a barrier
across flowing water that obstructs, directs or retards the flow, creating a
reservoir, lake or impoundment. A dam is the reservoir and not the whole
structure.
Uses of Dam: Dams are
built: To impound rivers and rainwater that can be used later to irrigate
agricultural fields. For electricity generation. Water supply for domestic and
industrial uses. Flood control. Recreation, inland navigation and fish
breeding.
Side effects of Creating Dams:
1.Regulating and damming of rivers affect their natural flow.
2.Poorer the habitats for the rivers’ aquatic life.
3. Fragment rivers make it difficult for aquatic fauna to migrate.
4.Dams created on the floodplains submerge the existing vegetation and soil
leading to its decomposition over a period of time.
4.Creating of large dams has been the cause of many new environmental
movements like the ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ etc.
5.Many times local people had to give up their land, livelihood and their
control over resources for the construction of the dam.
Most of the objections to the projects arose due to their failure to
achieve the purposes for which they were built. Most of the dams were
constructed to control floods but, these dams have triggered floods. Dams have
also caused extensive soil erosion. Excessive use of water has resulted in
earthquakes, caused water-borne diseases and pests and pollution
Multipurpose river valley projects —’The Temples of Modem India’: Jawahar Lal Nehru pro-claimed
that multipurpose projects are ‘The Temples of Modern India’, because they were
thought of as the vehicle that would lead the nation to development and
progress. He believed that these projects with their integrated water resource
management approach would integrate development of agriculture and the village
economy with rapid industrialization and growth of the urban economy.
Advantages of Multipurpose River valley
projects: They bring water to those areas which suffer from water
scarcity and also provide water for irrigation; These projects generate
electricity for industries and our homes; They help in controlling floods;
These projects can be used for recreation, inland navigation and fish breeding.
Disadvantages of
Multipurpose River valley projects: Damming of rivers
affects their natural flow causing poor sediment flow; Excessive sedimentation
at the bottom of the reservoir; Lack of sediments results in (a) rockier stream
bed and (b) poorer habitat for the rivers aquatic life; The reservoirs submerge
the existing vegetation and soil, leading to its decomposition over time; They
affect the fertility levels of the soil; cause large scale displacement of
local communities.
Traditional rainwater
harvesting methods practiced in different parts of the country:
-In mountainous areas ‘Guls’ and ‘Kul’s’ the
diversion channels were built for agriculture. ‘Rooftop rainwater harvesting’
was commonly practiced to store drinking water, especially in Rajasthan.
-Inundation channels for
irrigation were developed in the flood plains of West Bengal. ---In arid and
semi-arid regions, agricultural fields were converted into rain fed storage
structures, e.g., ‘Kadin’s’ in Jaisalmer and ‘Johad’s in other parts of
Rajasthan. In semi-arid and arid regions of Rajasthan, particularly in Bikaner,
Phalodi and Barmer areas for saving the rainwater. Many
houses constructed underground rooms adjoining the ‘tanka’ to beat the summer
heat as it would keep the room cool.
Interesting fact: Tamil Nadu is the first state in India which has
made rooftop rainwater harvesting structure compulsory to all the houses across
the state. There are legal provisions to punish the defaulters.
By-Vineeta Arya (TGT S.sc) KV DOGRA LINES MEERUT.
