Rainwater harvesting is the collection and storage of rainwater before it reaches the aquifer. It is practiced widely in parts of India like Tamil Nadu, Rajasthan, and Kerala. The process involves collecting rainwater via catchment areas and conduits, filtering it, and storing it in tanks to recharge groundwater. Advantages include providing an independent water supply during restrictions and promoting water and energy conservation.

2. 1. To keep rates low. Maximizing
current water supplies helps defer the
need to develop new, more expensive
sources of water.
2. To prepare for a drought. Many
areas of the country have experienced
drought conditions in the past few
years. Water conservation helps
prepare for these worst of times.
3. To comply with regulations. Many
states and local regulators have
established efficient water use
regulations.
4.To save money. Lower consumption
means lower water bills.
5. It is a resource that is a benefit to
everyone.

3. What is it?
Rainwater harvesting is the accumulation and deposition
of rainwater for reuse before it reaches the aquifer.
Advantages :-
Rainwater harvesting provides an independent water
supply during regional water restrictions .
Promotes both water and energy conservation
It helps in the availability of clean water by reducing
the salinity and the presence of iron salts.
Where in India is it practiced?
Tamil Nadu
Rajasthan
Kerala

4. How is it done?
Rainwater harvesting is done in 3 steps:1. Collecting and transporting water- done through catchment areas and
conduits.
2. Filtration -A filter unit is a chamber filled with filtering media to
remove debris and dirt from water before it enters the storage tank or
recharge structure.
3. Storage in tanks for recharging the groundwater- harvested water is
stored in tanks which is later used to recharge groundwater.

6. What is sustainable development?
Sustainable economic development or sustainability
means that ‘development should take place without
damaging the environment, and development in the
present should not compromise with the needs of the
future generations’.
Reasons for groundwater depletion :-
 The primary cause of groundwater depletion is
sustained groundwater pumping. We are
pumping out water at a faster rate than it is
getting replenished.

7. Effects of groundwater depletion :-
1. Lowering of the water table– caused by excessive pumping.
2. Increased costs- as the water table lowers, water must be pumped
farther to reach the surface, using more energy.
3. Land subsidence- Land subsidence occurs when there is a loss of
support below ground.
Ways to conserve groundwater :-
1. Reduce chemical use- we should minimize chemical use.
2. Manage waste- waste disposal should be watched over.
3. Save water- close the taps when not in use.

9. India’s growth story has been impressive so far
with industry and service sectors being the growth
drivers. Along with industrial and population
growth, the demand for water also increases.
Unpredictable rainfall patterns because of climate
change, depleting water resources because of
extreme groundwater extraction, contamination of
available surface/groundwater resources due to
discharge of untreated sewage, and/or industry
effluents have had an impact on water quantity
and quality. Per capita water availability is
expected to reach 1,140 cubic meters by 2050 from
1,820 cubic meters in 2001. As India’s water
problems are self-inflicted, the need to adopt
sustainable water management practices is crucial.

10. With mounting water issues, municipalities are
under stress to provide water (potable and nonpotable) to industrial, commercial, and
residential segments. Though wastewater
recycling and reuse is an option to meet water
requirements, some factors are limiting its
use, such as:• High price sensitivity towards advanced
wastewater treatment systems.
• Negative perception about wastewater
recycling .
• Lack of technological awareness and skilled
manpower .
• Fragmented nature of the market.
• Weak enforcement of regulations and policies.

11. There are many ways to recycle water. Out
of which some are stated below :1. Use gray water on garden and plantsGray water is termed for water which
is already used.
2. Use sink water to flush toilet waste.
3. Harvest rainwater- this will help us
save a considerable amount of water.
4. Reuse water that drains out of flower
pots.
5. Save kitchen water.

13. Objective :-
Narmada Bachao Andolan (NBA) is a social movement against a number of
large dams being built across the Narmada river. It aims to stop the building of
such dams.
Formation :-
There were groups such as Gujarat-based Narmada Asargrastha Samiti
(Committee for people affected by the Narmada dam), Madhya Pradesh-based
Narmada Ghati Nav Nirman Samiti (Committee for a new life in the
Narmada Valley) who either believed in the need for fair rehabilitation plans
for the people or who vehemently opposed dam construction despite a
resettlement policy.

14. People involved :-
Amongst the major celebrities who have shown their support for Narmada
Bachao Andolan are Booker Prize winner Arundhati Roy and Aamir Khan
Ways to pressurize the government:-
Within the focus of Narmada Bachao Andolan towards the stoppage of the
Sardar Sarovar dam, Patkar advised addition of World Bank to their
propaganda. Using the right to fasting, she undertook a 22-day fast that
almost took her life. In 1991, Patkar's actions led to an unprecedented
independent review by the World Bank.

15. Supreme court’s decision :-
The Supreme Court's decision is still pending, seeking stoppage of
construction of the Sardar sarovar dam. The court initially ruled the
decision in the Andolan's favor, thereby effecting an immediate stoppage
of work at the dam and directing the concerned states to first complete
the rehabilitation and replacement process.

17. This is the most traditional and reliable source of energy. A
quarter of our energy requirement is fulfilled by hydro power
plants. The kinetic energy of flowing water or the potential
energy of water at a height is used. Hydro power plants
convert the potential energy of falling water into electricity.
There are not many waterfalls for hydro power generation.
Therefore, it mainly depends on dams.
How do hydro power plants work:-
To produce hydel electricity, high rise dams are constructed on the
river to obstruct the flow of water and thereby collect water in
large reservoirs. The water level rises and in this process the kinetic
energy of flowing water gets transformed into potential energy.
The water from the high level in the dam is carried through pipes,
to the turbine at the bottom of the dam.

18. Due to the gravitational pull of mainly the moon on the spinning earth, the
level of sea water rises and falls. This phenomenon is called high and low
tides and the difference in sea level gives us the tidal energy. It is harnessed
by constructing a dam across a narrow opening to the sea. A turbine fixed at
the opening of the damn converts tidal energy to electricity. But, the
locations where these dams can be built are limited.

19. Due to geological changes, molten rocks formed in the deeper hot regions of
earth’s crust are pushed upward and trapped in certain regions called ‘hot
spots’. When underground water comes in contact with the hot spot, steam is
generated. Sometimes hot water from that region finds outlets at the surface.
Such outlets are known as hot springs. The steam trapped in rocks is routed
through a pipe to a turbine and used to generate electricity. There are very
few commercially viable sites where such energy can be exploited. There are
many geothermal power plants in New Zealand and United States of
America.

21. What is ‘hard water’?
Perhaps you must have noticed mineral deposits on your cooking dishes, or rings
of insoluble soap scum in your bathtub. These are signs of hard water from the
municipal water supply. Hard water is water that contains cations with a
charge of +2, especially Ca2+ and Mg2+. These ions do not pose any health
threat, but they can engage in reactions that leave insoluble mineral deposits.
These deposits can make hard water unsuitable for many uses, and so a variety
of means have been developed to "soften" hard water.
Problems with hard water :-
Mineral deposits are formed by ionic reactions resulting in the formation of an
insoluble precipitate. For example, when hard water is heated, Ca2+ ions react
with bicarbonate (HCO3) ions to form insoluble calcium carbonate (CaCO3)

22. Some strategies to soften hard water:-
Household water softeners typically use a different process, known as ion
exchange. Ion-exchange devices consist of a bed of plastic (polymer) beads
covalently bound to anion groups, such as -COO-. The negative charge of these
anions is balanced by Na+ cations attached to them. When water containing
Ca2+ and Mg2+ is passed through the ion exchanger, the Ca2+ and Mg2+ ions
are more attracted to the anion groups than the Na+ ions. Hence, they replace
the Na+ ions on the beads, and so the Na+ ions (which do not form scale) go
into the water in their place.

23. When hard tapwater passes through the ion exchanger (left), the calcium ions
from the tapwater replace the sodium ions in the ion exchanger. The softened
water, containing sodium ions in place of calcium ions, can be collected for
household use. Unfortunately, many people with high blood pressure or other
health problems must restrict their intake of sodium. Because water softened
by this type of ion exchange contains many sodium ions, people with limited
sodium intakes should avoid drinking water that has been softened this way.
Several new techniques for softening water without introducing sodium ions
are beginning to appear on the market.