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Water Scarcity - Its Measurement and Implications for Virtual Water Import

English title Water Scarcity - Its Measurement and Implications for Virtual Water Import
Applicant Yang Hong
Number 103600
Funding scheme Project funding (Div. I-III)
Research institution Eawag
Institution of higher education Swiss Federal Institute of Aquatic Science and Technology - EAWAG
Main discipline Other disciplines of Environmental Sciences
Start/End 01.04.2004 - 31.03.2007
Approved amount 123'658.00
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All Disciplines (2)

Discipline
Other disciplines of Environmental Sciences
Economics

Keywords (8)

Water Scarity; Food production capacity; Virtual water import; water scarcity; water productivity; food production; green water use; virtual water trade

Lay Summary (English)

Lead
Lay summary
The aim of this thesis was to develop a GIS-based EPIC model (GEPIC) to investigate water-food (crop) relations with a high spatial resolution on different geographical scales. The GEPIC model is applied for the analysis of crop water productivity (CWP), virtual water flows associated with food trade, and green and blue water contributions to food production.

A loose coupling approach was used to integrate the EPIC model with a Geographic Information System (GIS). This approach allows the transfer of data between a simulation model and GIS, while minimizing the requirement of additional programming. The GEPIC model enables an effective use of spatially distributed data such as precipitation, temperature, soil parameters, land use, irrigation and fertilizer application to analyze water-food relations.

The applicability of the GEPIC model is demonstrated for three cases. In the first case study, the GEPIC model was applied to calculate crop yields and CWP for wheat on a global scale with a spatial resolution of 30 arc-minutes. The validation suggests a good performance of the GEPIC model. A strong linear relationship was found between crop yield and CWP of wheat, implying that any management factors increasing crop yield may likely enhance CWP. Simulations under assumptions of sufficient water availability and fertilizer applications resulted in substantially increased wheat yield and CWP in many African countries.

The second case study dealt with testing the GEPIC model for a specific country (China) and crop (winter wheat). Irrigation depth, crop yield and CWP for winter wheat in China were simulated with a spatial resolution of 5 arc-minutes. The impacts of reducing irrigation water supply on wheat production were analyzed.

In the third case study, the GEPIC model was applied to simulate consumptive water use (CWU) and green water contribution to the production of 17 major crops on a global scale with a spatial resolution of 30 arc-minutes. The results show that over 80% of the global CWU was from green water. Almost 90% of the global virtual water trade among countries had its origin in green water. In the top ten net virtual water exporting countries, the proportions of green water in exports are generally higher than the proportions of green water in domestic production. High levels of net virtual water import (NVWI) generally occur in countries with low precipitation on a per capita basis.

In conclusion, the GEPIC model provides a systematic and flexible tool to study water-food relations on different geographical scales. With the GEPIC model, further research can be conducted to analyze the impacts of climate change on food production, the acceleration of nutrient cycles and increase in pollution by expanding food production, and the role of food trade in optimizing water resources management.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
138608 Spatially explicit modeling of impacts of adaptive agronomic measures on crop water productivity and yields in the context of water scarcity and climate change in Sub-Saharan Africa 01.02.2012 Interdisciplinary projects
122479 Global agricultural green and blue water consumptive uses and virtual water flows in the context of water scarcity and climate change 01.02.2009 Interdisciplinary projects

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