3R techniques


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There are many options and technologies available to apply the 3R concept in a watershed. During the Knowledge Exchange mission several 3R technologies that might be applied in the Kajiado area were introduced to the participants. Sander de Haas (PWN / SamSamWater) gave a presentation on several 3R technologies.

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3R techniques

  1. 1. 3R techniques (some examples)Sander de Haas (PWN, SamSamWater Foundation)31 October 2012, Kajiado, Kenya
  2. 2. www.samsamwater.com/climate
  3. 3. Rainfall in the Kajiado areaAbout 600 mm per year (on average)
  4. 4. Roof water harvesting
  5. 5. Roof water harvesting• 0,6 m3 per m2• Roof: 5 x 6 = 30 m2• 18 m3 per year = 18,000 litres per year = 49 litre per day = 5 buckets per day
  6. 6. Roof water harvestingAdvantages•Available near the house•Possible (almost) everywhereDisadvantages•Small volume•Relatively expensive (per litre)•Regular maintenance requiredHow to identify?•Suitable roof area (type + size)•Determine demand (domestic or more)•Calculate required tank size based on demand + availability
  7. 7. Rock catchment
  8. 8. Rock catchment
  9. 9. Rock catchment• Rock catchment: 200 m x 200 m x 0,6 m = 24,000 m3 = 24,000,000 litre per year = 66,000 litre per day
  10. 10. Rock catchmentAdvantages•Large volume•Low investment•Good qualityDisadvantages•Storage required•Need suitable locationHow to identify?•Suitable slope•(semi) impervious•Check during rains!•Calculate amount of water
  11. 11. ..
  12. 12. Catchment• River catchment: 2000 m x 2000 m x 0,6 m = 2,400,000 m3 = 2,400,000,000 litre per year = 6,600,000 litre per dayCombine 3R techniques to retain a part of this water!
  13. 13. Road catchment
  14. 14. Road catchmentAdvantages• Large catchment area -> a lot of water• Reduces road erosion• CheapDisadvantages• Poor water quality (oil leakage?)• Losses by evaporationHow to identify?• Check for runoff traces• Make use of existing structures / depressions
  15. 15. Recharge ponds
  16. 16. Recharge ponds
  17. 17. Recharge pondAdvantages• Water quality increased by filtration• Infiltration reduces evaporationDisadvantages• Need suitable geology• Not all water might be recovered• Shallow groundwater table neededHow to identify?• Permeable soil• Shallow groundwater available after rainy season
  18. 18. Sand dams
  19. 19. Sand dams / subsurface damsAdvantages• Sand acts as a natural filter• No evaporation, no mosquitoes• Relatively low cost (per litre)Disadvantages• Need suitable geology (sandy riverbed, impervious bedrock)• Risk of dam breach or erosion along sidesHow to identify?• Check for sand in riverbed• Check for groundwater in sand several time after the rains
  20. 20. Flood water diversion
  21. 21. Flood water diversionAdvantages• A lot of water available• Might reduce flash-flood problems downstreamDisadvantages• Large surface area needed• Risk of damage (houses, crops) when diverting flood waterHow to identify?• Check for suitable (flat) areas to divert the water to• Determine if flooding could cause problems (siltation, waterdamage, etc.)
  22. 22. Spring protectionAdvantages• Increases water qualityDisadvantages• Might have to find a solution for watering the animalsHow to identify?• Every spring deserves protection!• Identify potential risks for water quality(latrines, fertilisers, pesticides, cattle feaces, playingchildren, etc.)• Think of most suitable method (spring headprotection, runoff diversion, spring catchmentprotection, etc.) to reduce these risks.
  23. 23. Do you have any suggestions?Advantages• ...Disadvantages• ...How to identify?• ...
  24. 24. Case study: Elangata WuasThink of these (and other) options when we are in the field.Which options might be suitable for this site?How can we determine the possibilities in the field tomorrow?Can we estimate the potentially available amount? And howdoes this fit with the demand (domestic, animals)?
  25. 25. ConclusionNo single ‘magical’ 3R techniqueUse most suitable techniques for the siteCombine techniques to increase water availability and benefitfrom each otherMake use of the natural landscape and existing structures