Rainwater Harvesting By saralpushp
Why? Economics
Reduces water bills Reduced water demand - water supply utility saves money on on treatment and pumping Reduces cost of infrastructure necessary for water supply
Environment
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
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
S ourc e: http: //blog .s hunya.net/s hunyas_blog /2008/08/dholavir a-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
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 )
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 c rops
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 B urdak
Johads of Rajasthan (provide water for domestic use)
Photo by F arhad Contractor, taken in Alwar dis trict of R ajasthan 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)
Unique underground structures of various shapes and sizes to collect rain water for drinking purposes
Sometimes used to store drinking water brought from far off wells in case the rainwater gets exhausted
Constructed in court yards or in front of houses and temples,
Built both for individual households as well as for village communities
Tankas of Bikaner, Barmer, Phalodi - Rajasthan
Main source of drinking water in these areas
People protect and maintain them
Just before the on-set of the monsoon, the catchment area of the Tanka is cleaned up to remove all possible pollutants
Human activity and grazing of cattle in the area is prohibited
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.
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 •
Rajasthan Canal (Indira Gandhi Nahar Project) brings water (for agriculture and domestic use) from the Sutlej and Beas rivers
•
Rainwater harvesting was on decline
•
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 •
Water harvested in a system of tanks that were fed by seasonal streams
•
Tanks recharged groundwater
Deccan Plateau
Now • Tanks neglected
• Many regions facing water scarcity • Importance of rainwater harvesting being realized • Rooftop rainwater harvesting getting a boost
No perennial rivers
Rainwater harvesting in the North Eastern states Mountainous regions with heavy rainfall
http://media-2.web.britannica.com
• Uneven distribution of population • 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
200-year-old system
Used by tribal farmers of Khasi and Jaintia hills
Bamboos divert water from perennial springs on hilltops to the lower reaches by gravity
Used to irrigate the betel leaf or black pepper crops
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.
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
Gendathur (Karnataka) - a remote village in Mysore district
The first village to have installed a maximum number of rainwater harvesting systems.
Each of the 200 houses have a rooftop rainwater harvesting system
The Mysore Zilla Panchayat, an NGO (MYRADA) and the villagers worked together
The villagers contributed 20% of the project cost.
The villagers of Gendathur use rainwater for all their everyday needs; they even use it for drinking and cooking.
Some people
Chewang Norphel, 62, of Leh, Ladakh.
In Ladakh, the annual average rainfall is 50 mm. The only source of water are glaciers, which melt in late summer.
Water shortage felt at the start of the cropping season in early summer (May to June)
Taps left open in winter, so that water does not freeze in the pipelines (Water wasted in winter)
Norphel builds artificial glaciers by channelising glacier water into depressions lying in the shadow area of a mountain, hidden from sunlight.
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.
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.
• • • •
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
