Virtual water flows Methods of water accounting and examples Hong Yang Swiss Federal Institute for Aquatic Science and Technology (eawag) hong.yang@eawag.ch With contribution from Xu Zhao and Zhouying Zhang
1. Methods of virtual water accounting and interpretations of water saving associated with virtual water trade Virtual water content (m 3 /kg) (water requirement) is a function of climate conditions, agronomic practices, field management, etc. (the inversion of crop water productivity) VWC(m 3 /kg) WP(kg/m 3 ) Wheat: USA 1.30 0.77 Morocco 4.14 0.24 Algeria 7.22 0.14 Maize: France 0.35 2.85 USA 0.38 2.63 Mexico 1.34 0.75 Rice: China 1.07 0.94 Thailand 4.05 0.25 USA 1.33 0.75 2
Global map of water productivity of wheat, estimated with GEPIC (GIS based EPIC model) (1998-2002) 3
Virtual water flows (food crops) from export and import perspectives Virtual water import Real water use Real water saving Virtual water export 4
Global virtual water trade from import and export perspectives (1998-2002) 5
Impact of WP change on the volume of global water saving WP change Virtual water export virtual water import Water saving (km 3 /year) (km 3 /year) (km 3 /year) -20% 644 1225.9 581.9-10% 644 1089.7 445.7-5% 644 1032.3 388.3 Baseline 0% 644 980.7 336.7 5% 644 932.0 287.8 10% 644 882.9 238.7 20% 644 784.8 140.6 6
2. Relations between water scarcity and virtual water trade Net virtual water import by country groups, average of 1997-2001 (importing side). 7
Net cereal import [kg cap a] -100 0 100 200 300 400 500 600 Israel Emirates Jordan Libya Tunisia Algeria Yemen Cereal import and water resources (Blue water) Saudi Arabia Burundi Rwanda Egypt Morocco Kenya South Africa Zimbabwe Korea Rep Lebanon C 96-00 Malawi Iran Ethiopia Somalia Burkina Faso Pakistan India Mauritius (Yang et al., 2003) Lesotho Armenia Eritrea Korea Dem People's Rep Sri Lanka Azerbaijan China Nigeria Niger Ghana Turkey Afghanistan Tanzania Uganda Syria 0 1000 2000 3000 4000 5000 8 Water [ m 3 cap a] Togo Japan Mauritania Uzbekistan Senegal Benin
3. Water footprint accounting for impacts of virtual water trade on source regions Water footprint: The volume of freshwater used to produce the product, summed over the various steps of the production chain a consumption perspective The concept is in analogy to the ecological footprint, which is the area (productive land and aquatic ecosystems) needed to sustain people s living. 9
Why do we need the concept of water footprint in addition to virtual water? Water footprint: view water use from consumption aspect Link water use more closely with our daily life, 10
Types of water use during the production process WF proc, green = GreenWaterEvaporation + GreenWaterIncorporation WF proc, blue = BlueWaterEvaporation + BlueWater Incorporation+LostReturnFlow WF proc, grey = Volume of water that is required to dilute pollutants to such an extent that the quality of the ambient water remains above agreed water quality standards. 11
The water footprint and virtual water in a production chain Farmer Virtual water flow Food processer Virtual water flow Retailer Virtual water flow Consumer greengrey andwater blue water use Supply chain WF (indirect) blue grey water water use blue grey water water use Operational WF (direct) blue grey water water use End-use WF of a product The traditional statistics on corporate water use 12
National water footprint = local water use + VWI - VWE Feed Z A milk B Cheese Cheese C Re-export Cheese D A simplest example: milk-cheese 13
4. Input-output model for virtual water and water footprint accounting Input-output model, developed by Leontief (1941), is a technique to study the interconnections and interdependences of economic sectors. The IO-based WF accounting can calculate the virtual water import or export from the final demand of each sector. IO can be used to trace the source and destination of virtual water flows across river basins. 14
China s nine major watersheds The HHH region: Huanghe (Yellow River), Haihe, Huaihe 15
Net VW import in final demand of the Haihe basin years 1997, 2000 and 2002 (Zhao, Yang, et al., 2010) 6 1997 2000 2002 NVWIFD (Billion m 3 ) 4 2 0-2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Sectors 1. Agriculture, 2. Mining, 3. Food and tobacco processing, 4. Textile, 5. Lumbering and paper, 6, Petroleum processing, 7. Chemicals, 8. Non-metal mineral products, 9. Metal products, 10. Machinery and equipment, 11. Utilities, 12. Construction, 13. Wholesale 16 and retails, 14. Other services.
Water resources and virtual water export of the HHH region in China (Zhang, Yang, et al.) Water resources and virtual water export % 20 18 16 14 12 10 8 6 4 2 0 4.7 17.5 7.9 11.2 Share of HHH in national water resources Share of HHH in total virtual water export Ratio of HHH VW export to regional total water resources Ratio of HHH VW export in regional water use 17
HHH net virtual water export: 8137.8 million m 3 /year The Huang-Huai-Hai region 10.Non-metal mineral products 8% Other sectors 11% 4.Textile goods 36% VWE is making a big dirty footprint on its water bodies 5.Wearing 14% 3.Food and tobacco processing 15% 11.Metal smelting and products 16% Textile, food and tobacco processing, wearing amounts to 5301.3 million m3/year, 65% of total net VWE of the region 18
Questions: What is the connection between source and destination basins through virtual water trade? What are the impacts of virtual water flows on water resources in the source and destination basins? e.g., River-basin virtual water flows across river basins, China- Europe, China-USA, etc. 19
Thank you! Contact: Hong.yang@eawag.ch Eawag, Switzerland 20