Water Productivity

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Presented at the Basin Focal Project Review meeting in Cali, Colombia from 1-5 Feb, 2008

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Water Productivity

  1. 1. Water productivity Francis ‘n’ Simon
  2. 2. Purpose Method Progress Problems P bl Prospects
  3. 3. …it all seemed so simple when we started…
  4. 4. Simplify, then exaggerate Simplify
  5. 5. Complicate, simplify, then exaggerate
  6. 6. Complicate, simplify, complicate again….
  7. 7. Complicate, simplify, complicate, complicate simplify again….
  8. 8. Fascinating stuff
  9. 9. WPr: A basic measure of performance Benefit gained per volume water used
  10. 10. Rationale for increasing water productivity Global imperative – Meet combined targets of food and water security – CPWF target - “maintaining the level of global diversions of water, while increasing food production” Basin level rationale – Increase water availability to all – Reduce investment in water resources – Increase total benefits (variable) from water use (constrained). Water system level rationale y – Secure water for tail=end water users – Reduce O&M costs – Comply with water permit and pollution regulations Water users level rationale – Expand i i t d area E d irrigated – Reduce water costs – Increase agricultural output, food security and profitability Note: Trade-offs and synergies across scales
  11. 11. Method [grossly simplified]: [g y p ] – Define (sub) system – Estimate gain g – Estimate water use – Divide gain/WU g / – Portray as • Tables • Maps • Graphs – Interpret …[more later]
  12. 12. Estimating WPr g For an area… Gain Consumption – Yield, t, Price – Rainfall ~~ ET • Direct measure – Water balance • Secondary data y estimates • Remote sensing estimates – Crop ET – Corrections estimates (eg SEBALS, SEBS)
  13. 13. Progress g More crop per drop (WUE) Kgcrop/m3water – Irrigated crops – Rainfed crops $/m3, SGVP; multiple crops Livestock WPr….[close] Fish WPr …[not so close] [not Marginal WPr…[too hard] Relative WPr [dubious utlity] WPr….[dubious Multi-sector valuation…[too hard?]
  14. 14. Change (or lack of it) through time thro gh 0.800 Laos 3 productivity, kg/m 0.800 response Laos Water ductivity, kg/m3 0.600 Thailand WP k 0.600 0 600 Thailand 0.400 Cambodia 0.400 Cambodia Vietnam Water prod 0.200 Vietnam 0.200 crisis Vietnam Central highlands 0.000 Vietnam Central highlands M k hi hl t Vi d Vietnam Mekong 0.000 1990 1995 2000 2005 River Delta Vietnam Mekong timeDelta 1990 1995 Year 2000 2005 River Year
  15. 15. WP variation raises questions Maize WPr Volta
  16. 16. Water and agricultural production determinants as entry points for identifying intervention opportunities
  17. 17. WPr Gap p After FAO
  18. 18. Relative WP
  19. 19. Sometimes there appears an association Data sometimes shows association
  20. 20. Mapping Partial Water Productivity y 0.2-0.4 0204 1.2 1.6 1 2-1 6 0.8-1.2 0 8-1 2 0.6-0.8 0.4-0.6 Water productivity in rice – in kg / cubic meter of Et Frank’s Dream
  21. 21. Problems: Estimation Interpretation
  22. 22. Estimation – Benefit • Difficult to estimate amount – Areas don’t match, yield data uncertain, partial, etc • Worse to interpret – Who gains? What value? – Consumption • ET very difficult to assess • Water that flows through is not consumed • Pollution [usually not accounted] Aim: to increase total benefit [per person] / total consumption
  23. 23. Problem: Many different indicators and units y Output parameter Physical measures Physical/economic Economic Water input parameters measures measures ( (m3 or $ value) ) Biomass Harvestable Gross Net Gross Net yield value value value value (kg) ($) (kg) ($) ($) ($) Gross inflow kg/m3 kg/m3 $/m3 $/m3 ($/$) ($/$) Net inflow kg/m3 kg/m3 $/m3 $/m3 ($/$) ($/$) Available water kg/m3 kg/m3 $/m3 $/m3 ($/$) ($/$) Depleted water kg/m3 kg/m3 $/m3 $/m3 ($/$) ($/$) Beneficially depleted water kg/m3 kg/m3 $/m3 $/m3 ($/$) ($/$) Process depleted process water kg/m3 kg/m3 $/m3 $/m3 ($/$) ($/$)
  24. 24. Multiple gains in complex agricultural systems agric lt ral s stems Some agricultural production systems and their benefits. Agricultural Benefits production system Primary goods Secondary goods Services Soil cover to reduce Crop residue for p erosion, enhancing agro- , g g Crop production C d ti Harvestable yield H t bl i ld livestock feed biodiversity, carbon sequestration Draft power, manure, Livestock production Meat, milk and eggs leather Bio-diversity, water catchment protection, Tree production Timber, fuel wood Food carbon sequestration Bio-diversity of aquatic Fish production Meat Manure ecosystems
  25. 25. Problems of interpretation p A partial & comparative measure of performance p • 0.2 kg/m3 = bad; 0.8 kg/m3 = bad • An accounting variable • Maximize total gain /m3 consumed • But is water the important factor?
  26. 26. Final thoughts g (Meike’s slides)

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