Rainwater harvesting


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Rainwater harvesting

  1. 1. Rainwater Harvesting<br />
  2. 2. Why?<br />Economics<br /><ul><li>Reduces water bills
  3. 3. Reduced water demand - water supply utility saves money on treatment and pumping
  4. 4. Reduces cost of infrastructure necessary for water supply</li></ul>Environment<br /><ul><li>Energy saved – no pumping of water to our homes
  5. 5. If water is hard, adding soft rainwater improves water quality
  6. 6. Improves groundwater situation
  7. 7. Reduces demand for water at city / village level</li></ul>Other<br /><ul><li>Simple, cost-effective, easy to construct and maintain
  8. 8. Viable in urban and rural areas, slums, low income housing, apartments..
  9. 9. Can offset the need for multipurpose river projects</li></li></ul><li>How?<br />The concept is simple<br /><ul><li>Collect
  10. 10. Store and use
  11. 11. Recharge</li></li></ul><li>Not new to India<br />Rainwater storage reservoir at Dholavira (Rann of Kutch) – Harappan civilization (2500-1900 BC)<br />
  12. 12. Mountainous rain-shadow regions like Spiti valley<br />Flood plains to check floods during monsoons<br />The Deccan plateau which has only monsoon fed<br />(no perennial) rivers<br />Traditional rainwater harvesting systems<br />Widely prevalent in all parts of India<br />
  13. 13. Desert and arid region , Rajasthan, Rann of Kutch etc.<br />Traditional rainwater harvesting systems<br />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<br />Widely prevalent in all parts of India<br />
  14. 14. Centuries old ‘Kul irrigation’ in the Western Himalayan mountainous rain-shadow regions like Spiti valley<br />Glacier melt is diverted into the head of a ‘kul’ or a diversion channel<br />These ‘kuls’ channel the water over <br />many kilometers<br />They lead into a tank in the village from which water flow is regulated<br />
  15. 15. Fields<br />Fields<br />Inundation channelBengal Flood plains<br /><ul><li>Floodwater entered the fields through the inundation canals
  16. 16. The waters brought in rich silt and fish
  17. 17. The fish fed on mosquito larva and helped check malaria in this region.</li></ul>Embankment<br />River<br />Kana/ Nadi<br />
  18. 18. Khadins of Jaisalmer(harvesting structures for agricultural fields)<br /><ul><li> Designed by the Paliwal Brahmins of Jaisalmer, in 15th century
  19. 19. Similar system also practised in Ur (Iraq), the Negev desert, and in south west Colorado
  20. 20. An embankment prevents water from flowing away. Collected water seeps into the soil. </li></ul> This water saturates land, which is then used for growing crops<br />
  21. 21. Johads of Rajasthan(provide water for domestic use)<br /> Earthen or masonry rainwater harvesting structure, <br /> for providing water for domestic use to the communities.<br />Photo by L R Burdak<br />
  22. 22. Johads of Rajasthan(provide water for domestic use)<br />Photo by Farhad Contractor, taken in Alwar district of Rajasthan<br />Read about revival of Johads in ‘Reviving India’s water harvesting systems’ <br />
  23. 23. Tankas of Bikaner, Barmer, Phalodi - Rajasthan<br />Pipes from the rooftop lead rainwater into the tanka catchment<br />Note the slope provided for the rainwater (palar pani) to flow into the tanka<br />
  24. 24. Tankas for storing drinking waterThar desert region of Rajasthan (Barmer, Bikaner, Pallodi)<br /><ul><li>Unique underground structures of various shapes and sizes to collect rain water for drinking purposes
  25. 25. Sometimes used to store drinking water brought from far off wells in case the rainwater gets exhausted
  26. 26. Constructed in court yards or in front of houses and temples,
  27. 27. Built both for individual households as well as for village communities</li></li></ul><li>Tankas of Bikaner, Barmer, Phalodi - Rajasthan<br /><ul><li>Main source of drinking water in these areas
  28. 28. People protect and maintain them
  29. 29. Just before the on-set of the monsoon, the catchment area of the Tanka is cleaned up to remove all possible pollutants
  30. 30. Human activity and grazing of cattle in the area is prohibited
  31. 31. First spell of rain not collected </li></li></ul><li>Tankas of Bikaner, Barmer, Phalodi - Rajasthan<br /><ul><li> Provide enough drinking water to tide over the water scarcity during the summer months </li></ul> even though average annual rainfall is as less as 200 mm to 300 mm. <br /><ul><li> In many cases the stored water lasts for the whole year.
  32. 32. These simple traditional water harvesting structures are useful even during years of below-normal rainfall.</li></li></ul><li>Rainwater harvesting in Rajasthan today<br />Rajasthan Canal (Indira Gandhi Nahar Project) brings water (for agriculture and domestic use) from the Sutlej and Beas rivers<br />Rainwater harvesting was on decline<br />Being revived in many parts of Rajasthan: traditional methods with some improvisations<br />
  33. 33. Deccan Plateau<br />Then<br />Water harvested in a system of tanks that were fed by seasonal streams<br />Tanks recharged groundwater<br />Deccan Plateau<br />Now <br /><ul><li> Tanks neglected
  34. 34. Many regions facing water scarcity
  35. 35. Importance of rainwater harvesting being realized
  36. 36. Rooftop rainwater harvesting getting a boost</li></ul>No perennial rivers<br />
  37. 37. Rainwater harvesting in the North Eastern states<br />Mountainous regions with heavy rainfall<br />Uneven distribution of population<br />Abundant water resources but not tapped due to rugged terrain<br />Face water scarcity in areas of high population density<br />
  38. 38. Bamboo drip irrigation in Meghalaya<br />
  39. 39. Bamboo drip irrigation inMeghalaya<br /><ul><li>200-year-old system
  40. 40. Used by tribal farmers of Khasi and Jaintia hills
  41. 41. Bamboos divert water from perennial springs on hilltops to the lower reaches by gravity
  42. 42. Used to irrigate the betel leaf or black pepper crops
  43. 43. 18-20 litres of water entering the bamboo pipe </li></ul> system per minute gets transported over several <br /> hundred meters and finally gets reduced to 20-80 <br /> drops per minute at the site of the plant. <br /><ul><li>Attempts made to introduce modern pipe systems but farmers prefer to use their indigenous form of irrigation. </li></li></ul><li>Kunds/Kundis<br /> 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. <br />
  44. 44. Kunds/ Kundis<br /> 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.<br />
  45. 45. Rainwater harvesting today<br />Collection (Catchment)<br />Flat / sloping roofs <br />Transportation: Downtake pipes<br />Leaf and grit filter, First flush device<br />Storage in tanks<br />Recharge into open wells / borewells / percolation pits / trenches<br />
  46. 46. Case studies of interest - Legislation<br />Tamil Nadu<br /><ul><li>Rainwater harvesting made mandatory for all the buildings in the state
  47. 47. 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".
  48. 48. Citizens are also warned about disconnection of water supply connection if rainwater harvesting structures are not provided. </li></li></ul><li>Case studies of interest - Implementation<br />Karnataka<br /><ul><li>Gendathur (Karnataka)- a remote village in Mysore district
  49. 49. The first village to have installed a maximum number of rainwater harvesting systems.
  50. 50. Each of the 200 houses have a rooftop rainwater harvesting system
  51. 51. TheMysore Zilla Panchayat, an NGO (MYRADA) and the villagers worked together
  52. 52. The villagers contributed20%of the project cost.
  53. 53. The villagers ofGendathur use rainwater for all their everyday needs; they even use it for drinking and cooking. </li></li></ul><li>LehLadakh<br /><ul><li>ChewangNorphel, 62, of Leh, Ladakh.
  54. 54. In Ladakh, the annual average rainfall is 50 mm. </li></ul> The only source of water are glaciers, which melt in late <br /> summer. <br /><ul><li>Water shortage felt at the start of the cropping season in early summer (May to June)
  55. 55. Taps left open in winter, so that water does not freeze in the pipelines (Water wasted in winter)
  56. 56. Norphel builds artificial glaciers by channelising glacier water into depressions lying in the shadow area of a mountain, hidden from sunlight.
  57. 57. 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.
  58. 58. Norphel has made four such glaciers.</li></li></ul><li>Maharashtra - Phad<br />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).<br />
  59. 59. 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. <br />The phad system has given rise to a unique social system to manage water use. <br />
  60. 60. Karnataka - Kere<br /> 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. <br />This ensured:<br /> a) no wastage through overflow, and<br />b) the seepage of a tank higher up in the series would be collected in the next lower one.<br />
  61. 61. Katas / Mundas / Bandhas<br />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 <br />
  62. 62. 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. <br /> As a rule, there is a cut high<br /> up on the slope near one end<br /> of the embankment from<br /> where water is led either by a<br /> small channel or tal, or from<br /> field to field along terraces,<br /> going lower down to the fields. <br />
  63. 63. Want to play <br />
  64. 64. Divide the class into 5 teams<br />Team A selects 2 persons who will pick the clue and draw it out on the board for the other team members to guess. <br />If the guessers get the right answer in 30 secs, they get 5 points<br />If the guessers get the right answer in 60 secs, they get 3 points <br />Otherwise <br />The chance then goes to Team B and so on.<br />Rules<br />No mouthing of words<br />No names or numbers to be written<br />No actions<br />
  65. 65. Turn off the projector now, so that <br />the whole class cannot see the clues. <br />The 2 representatives of Team A<br />can come up to the computer and <br />see the clue.<br />Ready?<br />
  66. 66. Round 1<br />Team A – Khadin<br />Team B – Johad<br />Team C – Tanka<br />Team D – Kul<br />Team E – Inundation channel<br />
  67. 67. Round 2<br />Team A – Dholavira<br />Team B – Spiti valley<br />Team C – Rann of Kutch<br />Team D – Deccan Plateau<br />Team E – Jaisalmer<br />
  68. 68. Round 3<br />Team A – Thar<br />Team B – North East India<br />Team C – Bamboo drip irrigation<br />Team D – Indira Gandhi Canal<br />Team E – Gendathur<br />
  69. 69. Round 4<br />Team A – collection<br />Team B – storage<br />Team C – recharge<br />Team D – filter<br />Team E – pipelines<br />