*UPDATED* For 2022-23 Boards Exam
SHOBHIT NIRWAN's
DESIGNED
WATER RESOURCES
NOTES
Water: Some Facts and Figures
3/4th of Earth is covered with water.
Out of total volume of water on Earth 97.5% exists in oceans and seas.
About 2.5% of water is available as fresh water. And, 70% of this is present in
frozen ice in icebergs and glaciers.
Less than 30% of freshwater is stored as groundwater.
India receives nearly 4 percent of the global precipitation and ranks 133 in the
world in terms of water availability per person per annum.
By 2025, it is predicted that large parts of India will join countries or regions
having absolute water scarcity.
Why there is need for Water
Conservation & Management?
In a country like India, where population is growing at a fast rate. Demand for
water is increasing.
Indiscriminate pumping of water from tube wells leads to falling groundwater
levels. This adversely affects water availability and food security of the people in
the long.
Increasing numbers of industries has made matter worse by exerting pressure on
existing freshwater resources.
Electricity used by industries comes from hydroelectric power.
Most housing societies or colonies in the cities, have their own groundwater
pumping devices to meet their water needs. In most cases these are uncontrolled
leading to depletion in ground water levels.
Also, the scarcity may be due to bad quality of water. Much of water may be
polluted by domestic and industrial waste, chemicals, pesticides and fertilisers
used in agriculture, thus, making it hazardous for human use.
This excess use of chemical fertilisers and insecticides has contaminated
groundwater at many places, thus, making it hazardous for human use.
DAMS- A dam is a barrier across flowing water that obstructs, directs or retards the
flow, often creating a reservoir, lake or impoundment.
Multi-Purpose River Projects
Multi-purpose river projects large dams that serve several purposes in addition to
impounding the water of a river and used later to irrigate agricultural fields.
They help to control flood, check soil erosion, provide water for irrigation and
drinking purpose, generate electricity for industries, villages, cities, provide inland
navigation, help in preservation of wildlife and development or fisheries.
Dams are classified according to structure, intended purpose or height. Based on
structure and the materials used, dams are classified as timber dams,
embankment dams or masonry dams, with several subtypes.
Advantages of multi-purpose river projects are:
Electricity generation
Irrigation
Water supply for domestic and industrial uses
Flood control
Recreation
Inland navigation
Fish breeding
Disadvantages of Multi-purpose river projects are:
Affects the natural flow of river causing poor sediment flow and excessive
sedimentation at the bottom of the reservoir.
Destroys the habitats for the rivers' aquatic life.
Submerges the existing vegetation and soil if created on the floodplains.
Displaces the local people of the place where it is created.
These are unsuccessful in controlling floods at the time of excessive rainfall.
These projects induced earthquakes, caused water- borne diseases and pests
and pollution resulting from excessive use of water.
Rain Water Harvesting
Is a technique of increasing the recharge of groundwater by capturing and
storing rainwater by constructing wells, percolating pits and check dams.
Main objectives of the rainwater harvesting are:
To meet increasing demand of water To reduce runoff.
To avoid the flooding of roads.
To augment the groundwater storage and raise the water table.
To reduce groundwater pollution.
To improve the quality of groundwater.
To supplement domestic water requirement during summer and long dry
spells
Traditional rainwater harvesting methods practiced in different parts of the
country:
In mountainous areas ‘Guls’ and ‘Kuls’ 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., ‘Khadins’ in Jaisalmer and ‘Johads’ in other parts of
Rajasthan.
In semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi and
Banner, all the houses had underground tanks or ‘tankas’ built inside the
house for storing drinking water. They were a part of the well-developed
rooftop rainwater harvesting system.
Kuch Kaam Ki Baat (K3B) :
‘Narmada Bachao Andolan’:
Narmada Bachao Andolan or Save Narmada Movement is an NGO that mobilized
tribal people, farmers, environmentalists and human rights activists against the Sardar
Sarovar Dam being built across the Narmada river in Gujarat. The movement originally
focused on environmental issues related to submerging of trees under the dam water.
Recently its aim has been to enable the displaced poor people to get full
rehabilitation facilities from the government.
