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Drought management and water harvesting m5


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Definition of drought, Causes of drought, measures for water conservation and
augmentation, drought contingency planning. Water harvesting: rainwater
collection, small dams, runoff enhancement, runoff collection, ponds, tanks.

Published in: Education, Technology, Business

Drought management and water harvesting m5

  1. 1. MODULE- VDrought Management and Water Harvesting Prepared by Bibhabasu Mohanty Dept. of Civil Engineering SALITER, Ahmedabad
  2. 2. ContentsDefinition of drought, Causes of drought,measures for water conservation andaugmentation, drought contingencyplanning.Water harvesting: rainwater collection,small dams, runoff enhancement, runoffcollection, ponds, tanks.
  3. 3. IntroductionNormal, recurrent feature of climateOccurs everywhere, vary from region to region.Originates from deficiency of precipitation.Impact on ecosystem and agricultural of affected region.Drought leads to food insecurity, famine, malnutrition, epidemics and displacement of populations.
  4. 4. Types of droughtMeteorological droughtAgricultural droughtHydrological droughtSocioeconomic drought
  5. 5. Causes of droughtReduced rainfall results in drought.Occurs because water vapour not brought by air currents to right areas at right times.Unusual currents of cold and warm water in oceans creates high pressure. El Nino causes drought in Asia.Mountain prevent wind from blowing moisture to needy region.
  6. 6. In India when water vapour moves from east to west, water vapour does not leave Indian ocean causes drought.Human activity directly trigger over farming, excessive irrigation, deforestation.Global warming result in rainfall in some areas and drought in some areas.
  7. 7. Drought contingency planningTo provide contingency plans to manage drought and emergency conditions.To continue to deliver a cost effective, adequate, safe and reliable supply of water.The provision of credit or cash/food for workMaintaining water supply for animals and humans
  8. 8. Maintaining cereal availabilityHuman and livestock health service provisionSupport for private sectorProvide fodder for affected stockFlexible taxation systems for affected people
  9. 9. Drought contingency planning allow for implementation of :MitigationReliefRehabilitation
  10. 10. Drought contingency planning for implementation:Overall drought policy, setting out plans objectives of minimizing the impact of droughtSet plans for specific mitigation, relief and rehabilitation measuresConstruction of dams and additional reservoirs for supply of water.Cloud seeding- artificial rain
  11. 11. Desalination of sea water for irrigation or consumption.Drought monitoring by total rainfall levels and total usage levelsLand use by carefully planned crop rotationOutdoor water use restrictionRainwater harvestingRecycled waterRelief worksDisease prevention and control
  12. 12. • Contingency planning done by Govt. Policy issues, national, regional and district level rural development infrastructure input supply, marketing and farm advisory services• Non- Govt.NGO’SRural institutionsPrivate sectors
  13. 13. Augmentation of waterIt includes methods for providing an entirely new supply of fresh water and techniques for increasing utility of available supplies of water.New supply of water include weather modification.Weather modification done to increase precipitation and decrease Evapotranspiration.Cloud seeding done to increase precipitation.
  14. 14. Available water supplies increased by conservation of available water supplies.Agricultural water requirements can be reduced by reducing conveyance losses, and discouraging wasteful irrigation techniques.Technique should be developed to reduce water consumption in home and industry.Evaporation losses from small reservoirs can be reduced by providing roofs.
  15. 15. Reclamation and reuse of waste water can be encouraged.Evaporation loss in ground water is less. Use of ground water storage reservoir in conjunction with surface storage reservoirs.Infiltration losses can be reduced by sealing the soil surface useful in arid regions.Water harvesting done by collecting from roof top, pavements, constructing small storage.
  16. 16. Measures for water conservationGoals of water conservation efforts include:Sustainability- ensure availability for future generationsEnergy conservation- world 15% energy production dependent on water management.Habitat conservation- preserve fresh water habitat, migrating waterfowl.
  17. 17. Benefits of water conservation:Save water save money.Reduction in excess water use reduce waste water generation, reduce overflowing of gutter.Ecosystem and habitat protection.Helps in improving quality of drinking water.
  18. 18. Water conservation measures by:Domestic conservationIndustrial conservationAgricultural conservation
  19. 19. Domestic conservationRepair all leaks quicklyTurn off water when not in useUse conserving appliance which use low volume water for domestic useLocal bodies should install water meter and encourage water pricing.
  20. 20. Industrial conservationUse cooling system which use less water.Reuse of cooling water for irrigation or other purposes.Install in plant treatment measures for treating the waste water or effluent.
  21. 21. Agricultural (irrigation) conservationImproved irrigation methods such as sprinklers or drip irrigation.Water required for agricultural considerably reduced by reducing conveyance loss.Evaporation losses from small reservoirs can be reduced by providing roofs over them.Use of lined canals which reduce seepage and evaporation.
  22. 22. Use of ground water storage reservoir in conjunction with modern surface storage reservoirs to reduce evaporation loss, in arid regions.Price agricultural water to encourage conservation.Infiltration losses reduced by sealing soil surface.Water harvesting in arid regions.
  23. 23. For conservation of water the following structures can be constructed:Earthen bundGully pluggingCheck damKhet talawadi
  24. 24. Earthen bund
  25. 25. Gully plugging
  26. 26. Check dam
  27. 27. Khet Talawadi
  28. 28. Water harvestingCollection of rain water called water harvesting.Rainwater harvesting is accumulation and storing of rainwater for reuse, before it reaches aquifer.Water collected from roofs of houses, schools, local institutions make important contribution.Water collected from ground, called storm water harvesting.
  29. 29. Benefits of rainwater harvestingIncrease water availabilityChecks declining water tableEnvironmental friendlyImproves water quality of ground waterSurface water runoff conservationPrevents soil erosion and flooding in urban area
  30. 30. Rainwater harvesting techniqueRainwater collection – Roof top rainwater harvestingRunoff collection – Surface runoff harvestingRecharge to ground waterRunoff enhancement
  31. 31. Roof top rain water harvestingRainwater captured from roof catchments and stored in sub surface ground water reservoir.Objective is to make water available for future use.Useful in dry land, hilly, urban and costal areas.
  32. 32. Components of roof top rainwater harvesting a collection area a conveyance system storage facility a delivery systemStorage reservoir expensive part, careful design and construction required.First rainwater should be flushed or diverted.
  33. 33. Surface runoff harvestingSurface runoff harvesting is traditional technique.Small dams, ponds, tanks are used.Used for irrigation, domestic, livestock use.
  34. 34. Small damsSmall dams/check dams constructed in natural channel to impound the runoff water up to certain depth.Impounded water slowly infiltrate into soil and recharge ground water.
  35. 35. Ponds and reservoirsImpounding type and dug-cut type ponds constructed.In impounding type, a retaining wall or dam is constructed to block the flow of water in a natural storm.In dug-cut type area is excavated to store the runoff.Reservoirs requires water storage area, spillways and earth embankment.
  36. 36. Storage tankSurface or above ground tankSubsurface or underground tankStorage tanks requireSolid secure coverCoarse inlet filterOverflow pipeManhole, sump and drain to facilitate cleaningOutlet system, tap or pump
  37. 37. Recharge to ground waterThe structures generally used:PitsTrenchesDug wellHand pumpsRecharge wellSpreading techniquesUnderground reservoirs
  38. 38. Runoff enhancementCan be done by increase precipitation.Seeding generally done to increase precipitation.Precipitation can be increased by 10% by cloud seeding.Lumb demonstrated that increase in annual runoff (∆R) due to small increase in precipitation (∆P) is given by ∆R= ∆P (0.29+1.2 R/P)R= mean runoff, P= mean precipitation
  39. 39. Methods for runoff enhancement:Cloud seedingEnhancement by paved surfaces.Surface of drainage basin effect on runoff. Bare surface give more runoff.Drainage basin located on windward side of mountain produce more runoff.Runoff affected by geology of drainage basin. Pervious soil yield less runoff.
  40. 40. Drainage basin has larger no of natural depressions, which deposited by other material then runoff at basin increases.More Human activity, more load on soil, reduce infiltration, hence increase runoff.
  41. 41. ASSIGNMENT
  42. 42. 1. Discuss various causes of drought2. Discuss drought contingency planning and its importance.3. Explain augmentation of water and its various methods.4. Explain water conservation and its various methods.5. Discuss importance of rainwater harvesting and explain various techniques used for it.