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Green and Blue Water - a model & data based analysis of water scarcity, productivity (and trade) with a focus on the CPWF basins, by Holger Hoff, Dieter Gerten and Jens Heinke
The document summarizes analyses from an eco-hydrological model (LPJmL) regarding global water scarcity and agricultural productivity. It shows: 1) Current green and blue water availability per capita in major river basins. 2) Current crop water productivity (calories produced per cubic meter of water) in countries. 3) The maximum potential crop calorie production for each river basin based on current water availability and productivity. 4) Inter-annual variability in green and blue water availability for each basin as modeled by LPJmL versus observed CPWF data.
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Green and Blue Water - a model & data based analysis of water scarcity, productivity (and trade) with a focus on the CPWF basins, by Holger Hoff, Dieter Gerten and Jens Heinke
- 1. Green and BlueWater a model & data based analysis of water scarcity, productivity (and trade) with a focus on the CPWF basins Holger Hoff1,2, Dieter Gerten1 , Jens Heinke1 1:Potsdam Institute for Climate Impact Research 2: Stockholm Environment Institute & Resilience Centre
- 2. The LPJmL eco-hydrological& crop model biophysical processes at plant level CO2 Temperature Precipitation Radiation e.g. crop Interception production, Photosynthesis biofuels, carbon Transpiration sequestration Carbon / Water Balance Water resources Crop yields Evaporation Surface flow Subsurface flow consistent simulation of water resources, plant water use and productivity .
- 3. The LPJmL eco-hydrological& crop model landscape level livestock household precipitation partitioning into green & blue industry conveyance losses withdrawals evaporation interception lakes irrigation reservoirs transpiration Irrigation….. figure demand von Stefanie return flows evaporation surface runoff plant water supply subsurface runoff consistent calculation of green & blue virtual water contents (crops and other ecosystem services) AND water availability
- 4. The LPJmL eco-hydrological& crop model reservoirs Biemans et al 2011
- 5. current blue wateravailability per capita m3 cap-1 yr-1 adding green water (evapotranspiration from cropland)
- 6. current green &blue water availability per capita m3 cap-1 yr-1 discussion: country-wise aggregation of water for food potential for expanding cropland ?
- 7. current crop waterproductivity (kcal m-3) kcal m-3 Sri Lanka 2129 kcal m-3 India 1648 Bangladesh 2697 Pakistan 1218 water productivity -> weighted water availability
- 8. maximum calorie production(kcal cap-1) agricultural water productivity for current water availability & productivity kcal cap-1 day-1
- 9. CPWF basins current green & blue water availability per capita 6000 5000 4000 3000 m3 cap-1 year-1 blue water green wate 2000 1000 0 Ganges Indus Limpopo Mekong Niger Nile Sao Francisco Volta Ganges Indus Limpopo Mekong Niger Nile Sao Yellow Volta Yellow Francisco .
- 10. CPWF basins current crop water productivity (kcal m-3) 2500 2000 1500 factor 4 kcal m-3 1000 500 0 Ganges Indus Limpopo Mekong Niger Nile Sao Volta Yellow Francisco discussion: potential for closing the yield gap ? . .
- 11. CPWF basins maximum crop production (kcal cap-1) for current water availability & productivity 12000 10000 8000 kcal cap-1 day-1 6000 4000 3000 2000 0 po o lta w s g s er ile sc du ge on l lo ig po Vo N ci an In ek Ye N m an G M Li Fr o 3000 a tipping point? Sa 30 year averages .
- 12. CPWF basins inter-annual variability of green & blue water availability LPJmL vs CPWF data (1951-2000) 0.5 0.45 0.4 0.35 0.3 CP blue CoV 0.25 LPJ blue 0.2 CP green 0.15 LPJ green 0.1 0.05 0 Ganges Indus Limpopo Mekong Niger Nile Sao Volta Yellow Francisco 3000 a tipping point? .
- 13. CPWF basins factoring in variability 14000 12000 10000 kcal cap-1 day-1 8000 6000 4000 3000 2000 0 po o lta w s g s er ile sc du ge on l lo ig po Vo N ci an In ek Ye N m an G M Li Fr o 3000 a tipping point? Sa using 10th percentile instead of mean green & blue water availability . .
- 14. CPWF basins the future (2050) 14000 12000 10000 8000 kcal cap-1 day-1 6000 4000 3000 2000 0 po o lta w s g s er ile sc du ge on l lo ig po Vo N ci an In ek Ye N m an G M Li Fr o Sa discussion: 1) future crop water productivity (incl. CO2 effect)? 2) how much of the additional pressure is due to climate change? . .
- 15. future water demand 3,5 population change only 3 – relative to year 2000 Ganges 2,5 Indus Limpopo 2 Mekong Niger 1,5 Nile Sao Francisco 1 Volta Yellow 0,5 0 1990 2000 2010 2020 2030 2040 2050 2060 discussion: future populations and diets ? .
- 16. future (blue) wateravailability 1,2 1 Ganges Indus 0,8 Limpopo Mekong 0,6 Niger Nile 0,4 Sao Francisco climate change only Volta 0,2 – relative to year 2000 Yellow 0 1990 2000 2010 2020 2030 2040 2050 2060 . – 30 year averages, not accounting for changing variability, monsoon etc .
- 17. next steps: simulatingimpacts of variability, e.g. monsoon changes . Bondeau pers comm
- 18. next steps: simulatingland use change effects via “moisture recycling” Nikoli et al . Indus „precipitationshed“ .
- 19. next steps: simulatingland use change effects via “moisture recycling” (external driver) Nikoli et al 80 70 60 50 % internally generated 40 precipitation 30 20 internal 10 terrestrial 0 ao Francisco Niger Volta Nile Limpopo internalprecipitation Indus basin Yellow Mekong Ganges originating from terrestrial ET LPJmL simulations of ET changes with land use change
- 20. next steps: (“real”)water footprints of food production (and trade) plus other ecosystem services e.g. carbon sequestration %
- 21. LPJ-based crop virtualwater contents plus ComTrade data -> virtual water im- / exports consistent with water availability (“footprints”) Sri Lanka 100m3 cap-1 net import Cyprus India 5m3 cap-1 net export Bangladesh 30 m3 cap-1 net import Pakistan 2 m3 cap-1 net export discussion: what happens under increasing future water scarcity? see MENA example .
- 22. LPJ-based crop virtualwater contents plus ComTrade data -> virtual water im- / exports consistent with water availability (“footprints”) 1200 correlations of per capita net VW imports and VW imports (m**3) per capita & 1000 - blue water availability: Cyprus - 0.51 - blue plus green water avail: - 0.64 800 - water-limited potential kcal production: - 0.79 600 year 400 200 0 0 500 1000 1500 2000 2500 3000 3500 water-limited potential kcal production per capita & day .
- 23. 1) Effects ofinternational trade on local water resources a) in water scarce (MENA) countries m3 cap-1 yr-1 .