Transcript Rain Water Harvesting

Rainwater Harvesting
Std X – CBSE
As per NCERT Geography textbook
Contemporary India II
Why?
Economics
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Reduces water bills
Reduced water demand - water supply utility saves money on treatment and pumping
Reduces cost of infrastructure necessary for water supply
Environment
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Energy saved – no pumping of water to our homes
If water is hard, adding soft rainwater improves water quality
Improves groundwater situation
Reduces demand for water at city/village level
Other
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Simple, cost-effective, easy to construct and maintain
Viable in urban and rural areas, slums, low income housing, apartments
Can offset the need for multipurpose river projects
How?
The concept is simple
 Collect
 Store and use
 Recharge
Not new to India
Source: http://blog.shunya.net/shunyas_blog/2008/08/dholavira-a-har.html
Rainwater storage reservoir at Dholavira (Rann of Kutch) – Harappan
civilization (2500-1900 BC)
Traditional rainwater harvesting systems
Mountainous rain-shadow regions like Spiti valley
Flood plains to check floods during monsoons
The Deccan plateau which has only monsoon fed
(no perennial) rivers
Widely prevalent in all parts of India
Traditional rainwater harvesting systems
Mountainous regions with heavy rainfall to check erosion and
to provide water in non-rainy months since water
distribution systems are not easy to install
Desert and arid region , Rajasthan, Rann of Kutch etc.
Widely prevalent in all parts of India
Centuries old ‘Kul irrigation’ in the Western Himalayan
mountainous rain-shadow regions like Spiti valley
Glacier melt is diverted into the head of a ‘kul’ or a diversion channel
These ‘kuls’ channel the water over
many kilometers
They lead into a tank in the village from which water flow is regulated
Source: http://www.rainwaterharvesting.org/methods/traditional/kuls.htm Accessed November 2008
Inundation channel
Bengal Flood plains
Floodwater entered the fields through the inundation canals
 The waters brought in rich silt and fish
 The fish fed on mosquito larva and helped check malaria in this region.
Fields
Fields
Khadins of Jaisalmer
(harvesting structures for agricultural fields)
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Designed by the Paliwal Brahmins of Jaisalmer, in 15th century
 Similar system also practised in Ur (Iraq), the Negev desert, and in south west Colorado
 An embankment prevents water from flowing away. Collected water seeps into the soil.
This water saturates land, which is then used for growing crops
Johads of Rajasthan
(provide water for domestic use)
Earthen or masonry rainwater harvesting structure,
for providing water for domestic use to the communities.
Photo by L R Burdak
Johads of Rajasthan
(provide water for domestic use)
Photo by Farhad Contractor, taken in Alwar district of Rajasthan
Read about revival of Johads in ‘Reviving India’s water harvesting systems’
Tankas of Bikaner, Barmer, Phalodi - Rajasthan
Pipes from the rooftop lead
rainwater into the tanka
catchment
Note the slope provided for the rainwater
(palar pani) to flow into the tanka
Tankas for storing drinking water
Thar desert region of Rajasthan (Barmer, Bikaner, Pallodi)
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Unique underground structures of
various shapes and sizes to collect rain
water for drinking purposes
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Sometimes used to store drinking water
brought from far off wells in case the
rainwater gets exhausted
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Constructed in court yards or in front
of houses and temples,
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Built both for individual households as
well as for village communities
Tankas of Bikaner, Barmer, Phalodi - Rajasthan
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Main source of drinking water in these areas
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People protect and maintain them
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Just before the on-set of the monsoon, the catchment area of the Tanka is cleaned up to
remove all possible pollutants
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Human activity and grazing of cattle in the area is prohibited
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First spell of rain not collected
Tankas of Bikaner, Barmer, Phalodi - Rajasthan
 Provide enough drinking water to tide over the water scarcity during the summer months
even though average annual rainfall is as less as 200 mm to 300 mm.
 In many cases the stored water lasts for the whole year.
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These simple traditional water harvesting structures are useful even during years of belownormal rainfall.
http://twofloatingweeds.blogspot.com
http://pashunz.blogspot.com/2006_12_01_archive.html
Rainwater harvesting in Rajasthan today
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Rajasthan Canal (Indira Gandhi Nahar Project) brings water (for agriculture and domestic
use) from the Sutlej and Beas rivers
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Rainwater harvesting was on decline
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Being revived in many parts of Rajasthan: traditional methods with some improvisations
For more information, check out
http://www.rainwaterharvesting.org/Rural/Improvised.htm000
Deccan Plateau
Then
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Water harvested in a system of tanks that were fed
by seasonal streams
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Tanks recharged groundwater
Deccan
Plateau
Now
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Tanks neglected
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Many regions facing water scarcity
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Importance of rainwater harvesting being realized
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Rooftop rainwater harvesting getting a boost
No perennial rivers
Rainwater harvesting in the
North Eastern states
Mountainous regions with heavy rainfall
• Uneven distribution of population
http://media-2.web.britannica.com
• Abundant water resources but not tapped due to rugged terrain
• Face water scarcity in areas of high population density
Bamboo drip irrigation
in Meghalaya
Bamboo drip irrigation in Meghalaya
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200-year-old system
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Used by tribal farmers of Khasi and Jaintia hills
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Bamboos divert water from perennial springs on
hilltops to the lower reaches by gravity
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Used to irrigate the betel leaf or black pepper crops
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18-20 litres of water entering the bamboo pipe
system per minute gets transported over several
hundred meters and finally gets reduced to 20-80
drops per minute at the site of the plant.
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Attempts made to introduce modern pipe systems
but farmers prefer to use their indigenous form of
irrigation.
For more information on
Rain Water Harvesting Systems
in different regions
 Check out http://www.rainwaterharvesting.org/eco/eco-region.htm
 Read the book ‘Dying wisdom’ published by the Centre for Science and
Environment (CSE)
 Brief notes on some traditional water harvesting structures are available at
‘Traditional Water Harvesting Structures’ information sheet on
www.indiawaterportal.org
Rainwater harvesting today
Collection
(Catchment)
Flat / sloping roofs
Transportation: Downtake
pipes
Leaf and grit
filter, First
flush device
Storage in
tanks
Recharge into open wells /
borewells / percolation pits /
trenches
Case studies of interest - Legislation
Tamil Nadu
 Rainwater harvesting made mandatory for all the buildings in the
state
 If the rain water harvesting structure is not provided as required, an
authorized person can implement a rain water harvesting structure
and the cost is recovered along with property tax".
 Citizens are also warned about disconnection of water supply
connection if rainwater harvesting structures are not provided.
To learn more about policies and legislation (India and abroad),
check out http://www.rainwaterharvesting.org/Policy/Legislation.htm
Case studies of interest - Implementation
Karnataka
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Gendathur (Karnataka) - a remote village in Mysore district
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The first village to have installed a maximum number of rainwater harvesting systems.
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Each of the 200 houses have a rooftop rainwater harvesting system
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The Mysore Zilla Panchayat, an NGO (MYRADA) and the villagers worked together
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The villagers contributed 20% of the project cost.
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The villagers of Gendathur use rainwater for all their everyday needs; they even use it for
drinking and cooking.
Some people
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Chewang Norphel, 62, of Leh, Ladakh.
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In Ladakh, the annual average rainfall is 50 mm.
The only source of water are glaciers, which melt in late
summer.
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Water shortage felt at the start of the cropping season in early summer
(May to June)
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Taps left open in winter, so that water does not freeze in the pipelines
(Water wasted in winter)
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Norphel builds artificial glaciers by channelising glacier water into
depressions lying in the shadow area of a mountain, hidden from
sunlight.
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He places half-inch-wide iron pipes at the edge of the depression. As
the water keeps collecting in the pipes, it freezes. As more water seeps
in, it pushes out the frozen blocks, and in turn, itself gets frozen. This
keeps happening in a continuous cycle, and these frozen blocks create
a clean, artificial glacier.
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Norphel has made four such glaciers.
To learn more about people who are making a difference,
check out http://www.rainwaterharvesting.org/People/People.htm
Want to play
• Divide the class into 5 teams
• Team A selects 2 persons who will pick the clue and draw it out on the
board for the other team members to guess.
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If the guessers get the right answer in 30 secs, they get 5 points
If the guessers get the right answer in 60 secs, they get 3 points
Otherwise 
The chance then goes to Team B and so on.
Rules
• No mouthing of words
• No names or numbers to be written
• No actions
Turn off the projector now, so that
the whole class cannot see the clues.
The 2 representatives of Team A
can come up to the computer and
see the clue.
Ready?
Round 1
• Team A – Khadin
• Team B – Johad
• Team C – Tanka
• Team D – Kul
• Team E – Inundation channel
Round 2
• Team A – Dholavira
• Team B – Spiti valley
• Team C – Rann of Kutch
• Team D – Deccan Plateau
• Team E – Jaisalmer
Round 3
• Team A – Thar
• Team B – North East India
• Team C – Bamboo drip irrigation
• Team D – Indira Gandhi Canal
• Team E – Gendathur
Round 4
• Team A – collection
• Team B – storage
• Team C – recharge
• Team D – filter
• Team E – pipelines