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Rainwater harvesting

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Rainwater harvesting Rainwater harvesting Presentation Transcript

  • Rainwater Harvesting
  • Why?
    Economics
    • Reduces water bills
    • Reduced water demand - water supply utility saves money 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
    Rainwater storage reservoir at Dholavira (Rann of Kutch) – Harappan civilization (2500-1900 BC)
  • 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
    Traditional rainwater harvesting systems
    Widely prevalent in all parts of India
  • Desert and arid region , Rajasthan, Rann of Kutch etc.
    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
    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
  • Fields
    Fields
    Inundation channelBengal 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.
    Embankment
    River
    Kana/ Nadi
  • 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 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 waterThar 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 below-normal rainfall.
  • 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
  • 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
    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 inMeghalaya
    • 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.
  • Kunds/Kundis
    A kund or kundi looks like an upturned cup nestling in a saucer. These structures harvest rainwater for drinking, and dot the sandier tracts of the Thar Desert in western Rajasthan and some areas in Gujarat. Essentially a circular underground well, kunds have a saucer-shaped catchment area that gently slopes towards the centre where the well is situated. A wire mesh across water-inlets prevents debris from falling into the well-pit.
  • Kunds/ Kundis
    The sides of the well-pit are covered with (disinfectant) lime and ash. Most pits have a dome-shaped cover, or at least a lid, to protect the water. If need be, water can be drawn out with a bucket. The depth and diameter of kunds depend on their use (drinking, or domestic water requirements). They can be owned by only those with money to invest and land to construct it. Thus for the poor, large public kunds have to be built.
  • 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.
  • 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
    • TheMysore Zilla Panchayat, an NGO (MYRADA) and the villagers worked together
    • The villagers contributed20%of the project cost.
    • The villagers ofGendathur use rainwater for all their everyday needs; they even use it for drinking and cooking.
  • LehLadakh
    • ChewangNorphel, 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.
  • Maharashtra - Phad
    The community-managed phad irrigation system, prevalent in northwestern Maharashtra, probably came into existence some 300-400 years ago. The system operated on three rivers in the Tapi basin - Panjhra, Mosam and Aram - in Dhule and Nasik districts (still in use in some places here).
  • The size of a phad can vary from 10-200 ha, the average being 100-125 ha. Every year, the village decides which phads to use and which to leave fallow. Only one type of crop is allowed in one phad. Generally, sugarcane is grown in one or two phads; seasonal crops are grown in the others. This ensures a healthy crop rotation system that maintains soil fertility, and reduces the danger of waterlogging and salinity.
    The phad system has given rise to a unique social system to manage water use.
  • Karnataka - Kere
    Tanks, called kere in Kannada, were the predominant traditional method of irrigation in the Central Karnataka Plateau, and were fed either by channels branching off from anicuts (check dams) built across streams, or by streams in valleys. The outflow of one tank supplied the next all the way down the course of the stream; the tanks were built in a series, usually situated a few kilometres apart.
    This ensured:
    a) no wastage through overflow, and
    b) the seepage of a tank higher up in the series would be collected in the next lower one.
  • Katas / Mundas / Bandhas
    Katas / Mundas / BandhasThe katas, mundas and bandhas were the main irrigation sources in the ancient tribal kingdom of the Gonds (now in Orissa and Madhya Pradesh). Most of these katas were built by the village headmen known as gountias, who in turn, received the land from the Gond kings. Land here is classified into four groups on the basis of its topography: aat, (highland); mal (sloped land); berna (medium land); and bahal (low land). This classification helps to select
  • A kata is constructed north to south, or east to west, of avillage. A strong earthen embankment, curved at either end, is built across a drainage line to hold up an irregularly-shaped sheet of water. The undulations of the country usually determine its shape as that of a long isosceles triangle, of which the dam forms the base. It commands a valley, the bottom of which is the bahal land and the sides are the mal terrace.
    As a rule, there is a cut high
    up on the slope near one end
    of the embankment from
    where water is led either by a
    small channel or tal, or from
    field to field along terraces,
    going lower down to the fields.
  • 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
  • Round 4
    Team A – collection
    Team B – storage
    Team C – recharge
    Team D – filter
    Team E – pipelines