=Rain water harvesting =-

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  • Narration: T he hydrologic or water cycle is the continuous flow of water between reservoirs at or near the earth’s surface. As water falls to the ground as precipitation, it may develop as surface runoff into nearby surface waters or infiltrate into the ground and become stored as groundwater. Water stored in open areas, know as surface water, can evaporate into the atmosphere. In addition, water used by plants for normal growth or transpiration is also returned to the atmosphere. Once in the atmosphere water can condense into clouds and precipitate as rain or snowfall, initiating the cycle over again. Water is a renewable resource that, managed properly, can sustain the activities in the watershed for an indefinite period of time. Animation: shows water cycle
  • Narration: T he hydrologic or water cycle is the continuous flow of water between reservoirs at or near the earth’s surface. As water falls to the ground as precipitation, it may develop as surface runoff into nearby surface waters or infiltrate into the ground and become stored as groundwater. Water stored in open areas, know as surface water, can evaporate into the atmosphere. In addition, water used by plants for normal growth or transpiration is also returned to the atmosphere. Once in the atmosphere water can condense into clouds and precipitate as rain or snowfall, initiating the cycle over again. Water is a renewable resource that, managed properly, can sustain the activities in the watershed for an indefinite period of time. Animation: shows water cycle
  • The collection device usually represents the biggest capital investment of an RWH system. It therefore requires careful design- to provide optimal storage capacity while keeping the cost as low as possible. While above-ground structures like tanks are easily purchased or made with a variety of designs, and water extraction is in many cases by gravity; they also are expensive, require more space and are prone to attack from the weather. Below-ground structures like cisterns, lagoons etc. are generally cheaper due to lower material requirements and unobtrusive. However, water extraction often requires a pump, contamination is more common, and present a potential danger to children and small animals if left uncovered.
  • Whenever the depth of clay soil is more, recharge through a percolation pit with bore is preferable. This bore can be at the centre of the pit, which is filled with pebbles. The top portion is filled with river sand. The pit itself is covered with a perforated concrete slab. If the area is prone to flooding, it is advisable to provide an air vent to the percolation pit to avoid air locking. Roof water and surface water from buildings can be diverted to percolation pits. It is advisable to have at least one percolation pit in every house with open area for every 20 square metres.
  • Existing structures such as defunct bore wells, unused/dried up open wells, unused sumps, etc. can be very well used for RWH through this technology of recharge wells instead of constructing recharge structures to reduce the total cost

Transcript

  • 1. Rainwater Harvesting .ppt (1)
  • 2. Rain Water Harvesting?.• Rain Water Harvesting RWH- process of collecting,conveying & storing water from rainfall in an area – forbeneficial use.• Storage – in tanks, reservoirs, underground storage-groundwater• Hydrological Cycle
  • 3. What Is Rainwater Harvesting?RWH technology consists of simple systems to collect, convey,and store rainwater. Rainwater capture is accomplishedprimarily from roof-top, surface runoff, and other surfaces.RWH either captures stored rainwater for direct use (irrigation,production, washing, drinking water, etc.) or is recharged intothe local ground water and is call artificial recharge.In many cases, RWH systems are used in conjunction withAquifer Storage and Recovery (ASR). ASR is the introductionof RWH collected rainwater to the groundwater / aquiferthrough various structures in excess of what would naturallyinfiltrate then recovered for use .ppt (3)
  • 4. Why Rainwater Harvesting?Conserve and supplement existing water resourcesAvailable for capture and storage in most globallocationsPotentially provide improved quality of waterSupply water at one of the lowest costs possible for asupplemental supply source.Capturing and directing storm water (run-off) andbeneficially use itCommitment as a corporate citizen - showcasingenvironmental concernsPublic Mandate (India)Replenishing local ground water aquifers where l oweringof water tables has occured .ppt (4)
  • 5. Why Not RWH?Not applicable in all climate conditions over the worldPerformance seriously affected by climate fluctuations that sometimes are hard to predictIncreasingly sophisticated RWH systems (ASR) necessarily increases complexities in cost, design, operation, maintenance, size and regulatory permittingCollected rainwater can be degraded with the inclusion of storm water runoffCollected water quality might be affected by external factorsCollection systems require monitoring and continuous maintenance and improvement to maintain desired water quality characteristics for water end-useCertain areas will have high initial capital cost with low ROI .ppt (5)
  • 6. Condensation Let’s take a look at Precipitation The Water Cycle Evapotranspiration EvaporationInfiltration Surface Runoff Grou Consumption Surface Water n dw ater Sea water intrusion .ppt (6)
  • 7. Condensation Rainfall Definitions Intensity – Quantity per time ofPrecipitation the rainfall event (mm/hour) Duration – period of time for the precipitation event Average Annual and Monthly Precipitation – Average rainfall over one year period and monthly intervals and usually based on 30 or more years of Consumption data Grou ndw ater Surface Water .ppt (7)
  • 8. Rain Water as Source Water Design Considerations 1 2 Typical Diagram Recomendation 4 3 5 6 Raw water tank or Aquifer 71 Roof 4 Pre-filter2 Screen 5 Storage tank3 Discharge of water 6 Flow meter 7 Storm water discharge .ppt (8)
  • 9. Ground Water RechargeUnder natural conditions it may take days to centuries to recharge ground waterby rain water. As we need to replenish the pumped water, Artificial Recharge ofGround water is required at some locations. .ppt (9)
  • 10. Appropriate Water conservation and groundwaterTechnology recharge techniques Water harvesting cum supplementary irrigation techniques in Jhabua
  • 11. Ground catchments systems channel water from a prepared catchmentarea into storage. Generally they are only considered in areas whererainwater is very scarce and other sources of water are not available.They are more suited to small communities than individual families. Ifproperly designed, ground catchment systems can collect largequantities of rainwater. .ppt (11)
  • 12. Storage • Storage devices may be either above or below ground • Different types include  Storage Tanks  Water Containers  Lagoons or Lined Ponds  Infiltration Ponds  Size based on rainfall pattern, demand, budget and area .ppt (12)
  • 13. Percolation Pit To divert rainwater into an aquifer, The percolation pit is covered with a perforated concrete slab The pit is filled with gravel/ pebbles followed by river sand for better percolation. The top layer of sand must be cleaned and replaced at least once in two years to remove settled silt for improving the percolation .ppt (13)
  • 14. RWH – Methodologies• Roof Rain Water Harvesting• Land based Rain Water Harvesting• Watershed based Rain Water harvesting • For Urban & Industrial Environment – • Roof & Land based RWH • Public, Private, Office & Industrial buildings • Pavements, Lawns, Gardens & other open spaces
  • 15. Recharge Wells The runoff water from rooftops or other catchments can be channelized into an existing /new well via sand filter to filter turbidity and other pollutants Abandoned wells can also be used Cost-effective process, which not only conserves rainwater for immediate use but also helps to enhance the local ground water situation .ppt (15)
  • 16. Quality Issues Roofs contain: bird droppings, atmospheric dust, industrial and urban air pollution .ppt (16)
  • 17. Operational Procedures and Design Considerations • Storage tank – dark materials to exclude light and algae formation • Corrosion resistant materials • Tank in protected shaded area – lower temperature • For multiple storage tanks – design for frequent turnover • Regional wind direction and industrial activity – Lead, Mercury, other heavy metals .ppt (17)
  • 18. RAIN W ATER HARVESTING FOR OFFICES – Developing a GREEN BUILDING inNairobi, Kenya RAIN WATER ACCUMULATION IN LIEU OF STORM WATER ATTENUATION POND GREEN ROOF GREEN ROOF MANICURED LAWN GARDEN POROUS PARKING OZONATION FILTRATION OVERFLOW BACKUP MUNICIPAL SUPPLY Co nc e p t & De s ig n Princ ip le s GROUND WATER REPLENISHING WELLS .ppt (18)
  • 19. PRINCIPLES OF A GREEN BUILDING - WATERSYSTEM OF RAIN WATER HARVESTING AND GREY WATER ARECOMBINED TO ACHIEVE THE FOLLOWING:• 25% OF POTABLE WATER CONSUMPTION REDUCTION• 100% OF POTABLE WATER PROVIDED BY RAIN• 50% REDUCTION OF SEWER QUANTITIES .ppt (19)