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Science ppt

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  • 1. Seminar on :RAIN WATER HARVESTING Presented by: Vivekanand. S.Murashillin Xth b Roll no:24 subject : science
  • 2. SAVE WATER:RAIN WATERHARVESTING
  • 3. WHAT IS RAIN WATER HARVESTING Rainwater harvesting is the accumulating and storing of rainwater for reuse before it reaches the aquifer. The principle of collecting and using precipitation from a catchments surface
  • 4. WHY RAIN WATER HARVESTING Surface water is inadequate to meet our demand and we have to depend on ground water. To arrest ground water decline and augment ground water table To beneficiate water quality in aquifers To conserve surface water runoff during monsoon To reduce soil erosion Due to rapid urbanization, infiltration of rain water into the sub-soil has decreased drastically and recharging of ground water has diminished.
  • 5. RAIN WATER PATTERN IN INDIA Total annual rainfall in India: 400 million hectare- meters (area x height) India’s area: 329 million hectares If evenly spread, average height: 1.28m Actual distribution:  Highly skewed area-wise  Thar desert receives less than 200mm annually, while Cherrapunji receives 11,400mm  But almost every part of India receives at least 100mm annually Key: even 100mm annual rainfall sufficient if harvested properly and where it falls
  • 6. RAIN WATER HARVESTINGTECHNIQUES :  Roof top rainwater harvesting.  Surface runoff harvesting .
  • 7. ELEMENTS OF ROOFTOP RWH CATCHMENT COUNDITS FILTERS STORAGE FACILITY
  • 8. METHODS OF ROOFTOP RWH Storage of direct use Recharging ground water aquifer - Recharging dug wells - Recharging pits - Recharging tube well
  • 9. SURFACE RUNOFF HARVESTING Harvesting of surface runoff and storage of the same into reservoirs such as water pans makes it available for use when required. In this method of collecting rainwater for irrigation, water flowing along the ground during the rains will be collected to a tank below the surface of the ground..
  • 10. TRADITIONAL RWH STRUCTUREBAWODI:Traditional step wells are calledvavadi in Gujarat, or baoris orbavadis in Rajasthan andnorthern India.They were secular structures fromwhich everyone could draw water.Most of them are defunct today.
  • 11. JOHADSA johad is a crescent-shaped bund which isbuilt across a slopingcatchment to capturethe surface water beforeit runs off.Water accumulating inthe johad percolates inthe soil to augment thegroundwater. Thegroundwater then canbe used when there is norainfall.
  • 12. USES OF RAINWATER HARVESTING Domestic Use Agricultural Use Increase groundwater supplies
  • 13. POTENTIAL OF RWH Impacts on downstream flows. Reduce soil erosion. Increase the crop production. Increase infiltration and groundwater recharge. Improve food & economic security.
  • 14. ADVANTAGE It uses local construction materials and labor. Sources of energy are not needed to operate the systems. The owner/user can easily maintain the systems. The water is convenient and accessible; valuable time and effort are saved in collecting and/or hauling water. It provides a supply of water to meet future agricultural needs.
  • 15. RWH: A NOBLE GOALA COMMON RESPONSIBILITY