Global agricultural green and blue water Global agricultural green and blue water consumptive uses and virtual water trade consumptive uses and virtual water trade
in the context of water scarcity and in the context of water scarcity and
climate change climate change
Hong Yang
Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland
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Content
Global crop consumptive water use and virtual water trade – status quo
Impact of climate change on water availability - case of Iran
Impact of climate change on crop production and implications for food security– case of Africa
Uncertainties in the projections of future climate changes and impact on crop production
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Global crop consumptive water use and virtual water trade
(Estimated with the GEPIC model)
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Estimation of crop water uses – Coupling GIS with crop growth model
ET Yield Biomass Irrigation Nutrient
GIS ….
EPIC
Site-specific inputs
• Climate
• Soil
• Land use
• Management
…….
Site-specific outputs
• Crop yield
• ET
• CWP
…….
Climate Soil
Land use Irrigation DEM….
GEPIC
Input maps and data
Grid-base output maps
GIS GIS EPIC EPIC
Site-specific inputs
• Climate
• Soil
• Land use
• Management
…….
Site-specific outputs
• Crop yield
• ET
• CWP, Biomss, Irrigation Nutrients,
….
…….
Climate Soil
Land use Irrigation DEM….
Climate Soil
Land use Irrigation DEM….
Fertilizer Pesticides
…
GEPIC
Input maps and data
Grid-base output maps
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Methodology: Flowchart of GIS-EPIC integration
Y GIS Input
Datasets
Text Input
Files UTIL EPIC Input
Files EPIC
Text Output files (ET/Y/CWP)
EPIC Output Files Input Data
Translation Module
Batch File
Output Data Translation Module Others
Irrigation Land use
Climate Soil Slope DEM
Meteorological databases Soil databases
CWP ET Yield GIS Output Maps
End of Grid Simulation N
ArcGIS 9
6
Spatial distribution of consumptive water use for crop
production per grid cell of 30 arc minutes (average over 1998- 2002)
Global map of simulated crop water productivity of wheat (2000)7
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Global Consumptive Water Use (total: 3823 km3 yr-1)
Wheat 18%
Rice 27%
Barley 4%
Sorghum 4%
Millet 2%
Rye 1%
Other 68%
Maize 13%
Sugarbeet 1%
Seed cotton
4% Soybean 11%
Groundnut 2%
Rapeseed 1%
Sugar cane 4%
Sunflower 2%
Pulse 5%
Cassava 2%
Potato 1%
Global consumptive water use for individual crops (average over 1998-2002)
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Global Green Water Proportion in Crop Production
0 20 40 60 80 100
Cassava Rye Millet Barley Rseed Pulse Sorghum Soybean Rice Sflow er Potato Groundnut Maize Wheat Sugarbeet Sugarcane Cotton
Green Water Contribution (%)
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Green Water Proportion
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Total net blue and green virtual water export in major exporting countries (average over 1998-2002).
82% 98%
96%
92% 82%
91% 96%
97%
96%
80%
0 30 60 90 120 150
USA Australia Argentina France Canada Ukraine India Brazil Kazakhstan Paraguay
Total Net Virtual Water Export [km3 /year] Green virtual water export Blue virtual water export
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Some numbers
• Average CWU for the 17 major crops is 3823 km3/year (with a range between 2559 km3/year and 5554
km3/year).
• Of the total CWU, 81% is from green water.
• Green water accounts for 94% of global virtual water export.
Relationship between net virtual water export and consumptive 13
water use in net exporting countries
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Iceland
Saudi Arabia
Japan Portugal
Netherlands
Belgium Israel
Oman Jordan
Mauritania
Eritrea
Mongolia
Zambia Kenya
0 200 400 600 800 1000
0 100 200 300 400 500 600 700 800
CWU [m3/cap/yr]
NVWI [m3 /cap/yr]
High-income country Middle-income country Low -income country
Relationship between net virtual water import and consumptive water use in importing countries
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Impact of Climate Change on Water Availability – Case of Iran
(Estimated with the SWAT model)
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IPCC
Scenarios
17
18
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Blue water availability at sub-basin level in Iran
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Changes in blue water availability in Iran
• Blue water and green water at the provincial level 21
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Impact of Climate Change on Crop Production and Food Supply in Africa
(Estimated with the GEPIC model)
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Impact of Climate Change on Crop Yield (A1)
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Impact of Climate Change on Crop Yield
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Impact of Climate Change on Crop Production
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Future Hotspots
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Uncertainty in the projections of future climate changes and impact on crop
production
Future change in water-productivity of maize under three GCMs 28
(HadCM3, PCM, and CSIRO2) and two SRES scenarios (A1FI and B2).
Future change in maize production under three GCMs 29
(HadCM3, PCM, and CSIRO2) and two SRES scenarios (A1FI and B2).
30
-20 0 20 40 60 80 100
DR Congo
Ethiopia
Ghana
Kenya
Malawi
Nigeria
South Africa
Tanzania
Zambia
Zimbabwe
Import / Demand [%]
Current
HadCM3 A1FI PCM A1FI CSIRO2 A1FI
Ratio of maize import to total domestic demand (%, import dependency)
Current and 2030s
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Contact:
Hong.yang@eawag.ch
EAWAG, Duebendorf, Switzerland
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• Yang, H., Zehnder, A.J.B. 2007. ‘Virtual water - an unfolding concept in integrated water resources management’. Water Resources Research. 43, doi:10.1029/2007WR006048.
• Abbaspour, K. C., M. Faramarzi, S. S. Ghasemi, and H.
Yang. 2009. Assessing the Impact of Climate Change on Water Resources of Iran, Water Resource Research,
doi:10.1029/2008WR007615, in press.
• Liu J., Fritz S., van Wesenbeeck C.F.A., Fuchs M.,
Obersteiner M., Yang H., 2008. A spatial explicit assessment of current and future hotspots of hunger in Sub-Saharan
Africa in the context of global change. Global and Planetary Change. doi:10.1016/j.gloplacha.2008.09.007.
• Liu J.G., A.J.B., Zehnder, H. Yang, 2009. Global consuptive water use for crop production: the importance of green water and virtual water. Water Resources Research, 45. doi:
10.1029/2007WR006051.
